JSP技术简介(外文翻译)
JSP技术概述与应用框架外文翻译
外文原文Overview of JSP Technology and JSP application frameworksAutor: Zambon Giulio/ Sekler MichaelSource: Springer-Verlag New York Inc1．Benefits of JSPJSP pages are translated into servlets. So, fundamentally, any task JSP pages can perform could also be accomplished by servlets. However, this underlying equivalence does not mean that servlets and JSP pages are equally appropriate in all scenarios. The issue is not the power of the technology, it is the convenience, productivity, and maintainability of one or the other. After all, anything you can do on a particular computer platform in the Java programming language you could also do in assembly language. But it still matters which you choose.JSP provides the following benefits over servlets alone:• It is easier to write and maintain the HTML. Your static code is ordinary HTML: no extra backslashes, no double quotes, and no lurking Java syntax.• You can use standard Web-site development tools. Even HTML tools that know nothing about JSP can be used because they simply ignore the JSP tags.• You can divide up your development team. The Java programmers can work on the dynamic code. The Web developers can concentrate on the presentation layer. On large projects, this division is very important. Depending on the size of your team and the complexity of your project, you can enforce a weaker or stronger separation between the static HTML and the dynamic content.Now, this discussion is not to say that you should stop using servlets and use only JSP instead. By no means. Almost all projects will use both. For some requests in your project, you will use servlets. For others, you will use JSP. For still others, you will combine them with the MVC architecture . You want the appropriate tool for the job, and servlets, by themselves, do not complete your toolkit.2.Advantages of JSP Over Competing TechnologiesA number of years ago, Marty was invited to attend a small 20-person industry roundtable discussion on software technology. Sitting in the seat next to Marty was James Gosling, inventor of the Java programming language. Sitting several seats away was a high-level manager from a very large software company in Redmond, Washington. During the discussion, the moderator brought up the subject of Jini, which at that time was a new Java technology. The moderator asked the manager what he thought of it, and the manager responded that it was too early to tell, but that it seemed to be an excellent idea. He went on tosay that they would keep an eye on it, and if it seemed to be catching on, they would follow his company's usual "embrace and extend" strategy. At this point, Gosling lightheartedly interjected "You mean disgrace and distend."Now, the grievance that Gosling was airing was that he felt that this company would take technology from other companies and suborn it for their own purposes. But guess what? The shoe is on the other foot here. The Java community did not invent the idea of designing pages as a mixture of static HTML and dynamic code marked with special tags. For example, ColdFusion did it years earlier. Even ASP (a product from the very software company of the aforementioned manager) popularized this approach before JSP came along and decided to jump on the bandwagon. In fact, JSP not only adopted the general idea, it even used many of the same special tags as ASP did..So, the question becomes: why use JSP instead of one of these other technologies? Our first response is that we are not arguing that everyone should. Several of those other technologies are quite good and are reasonable options in some situations. In other situations, however, JSP is clearly better. Here are a few of the reasons. 2.1 Versus .NET and Active Server Pages (ASP). NET is well-designed technology from Microsoft. is the part that directly competes with servlets and JSP. The advantages of JSP are two fold.First, JSP is portable to multiple operating systems and Web servers; you aren't locked into deploying on Windows and IIS. Although the core .NET platform runs on a few non-Windows platforms, the ASP part does not. You cannot expect to deploy serious applications on multiple servers and operating systems. For some applications, this difference does not matter. For others, it matters greatly.Second, for some applications the choice of the underlying language matters greatly. For example, although .NET's C# language is very well designed and is similar to Java, fewer programmers are familiar with either the core C# syntax or the many auxiliary libraries. In addition, many developers still use the original version of ASP. With this version, JSP has a clear advantage for the dynamic code. With JSP, the dynamic part is written in Java, not VBScript or another ASP-specific language, so JSP is more powerful and better suited to complex applications that require reusable components.You could make the same argument when comparing JSP to the previous version of ColdFusion; with JSP you can use Java for the "real code" and are not tied to a particular server product. However, the current release of ColdFusion is within the context of a J2EE server, allowing developers to easily mix ColdFusion and servlet/JSP code.2.2 Versus PHPPHP (a recursive acronym for "PHP: Hypertext Preprocessor") is a free, open-source, HTML-embedded scripting language that is somewhat similar to both ASP and JSP. Oneadvantage of JSP is that the dynamic part is written in Java, which already has an extensive API for networking, database access, distributed objects, and the like, whereas PHP requires learning an entirely new, less widely used language. A second advantage is that JSP is much more widely supported by tool and server vendors than is PHP.2.3 Versus Pure ServletsJSP doesn't provide any capabilities that couldn't, in principle, be accomplished with servlets. In fact, JSP documents are automatically translated into servlets behind the scenes. But it is more convenient to write (and to modify!) regular HTML than to use a zillion println statements to generate the HTML. Plus, by separating the presentation from the content, you can put different people on different tasks: your Web page design experts can build the HTML by using familiar tools and either leave places for your servlet programmers to insert the dynamic content or invoke the dynamic content indirectly by means of XML tags.Does this mean that you can just learn JSP and forget about servlets? Absolutely not! JSP developers need to know servlets for four reasons:1. JSP pages get translated into servlets. You can't understand how JSP works without understanding servlets.2. JSP consists of static HTML, special-purpose JSP tags, and Java code. What kind of Java code? Servlet code! You can't write that code if you don't understand servlet programming.3. Some tasks are better accomplished by servlets than by JSP. JSP is good at generating pages that consist of large sections of fairly well structured HTML or other character data. Servlets are better for generating binary data, building pages with highly variable structure, and performing tasks (such as redirection) that involve little or no output.4. Some tasks are better accomplished by a combination of servlets and JSP than by either servlets or JSP alone.2.4 Versus JavaScriptJavaScript, which is completely distinct from the Java programming language, is normally used to dynamically generate HTML on the client, building parts of the Web page as the browser loads the document. This is a useful capability and does not normally overlap with the capabilities of JSP (which runs only on the server). JSP pages still include SCRIPT tags for JavaScript, just as normal HTML pages do. In fact, JSP can even be used to dynamically generate the JavaScript that will be sent to the client. So, JavaScript is not a competing technology; it is a complementary one.It is also possible to use JavaScript on the server, most notably on Sun ONE (formerly iPlanet), IIS, and BroadVision servers. However, Java is more powerful, flexible, reliable, and portable.2.5 Versus WebMacro or VelocityJSP is by no means perfect. Many people have pointed out features that could be improved. This is a good thing, and one of the advantages of JSP is that the specification is controlled by a community that draws from many different companies. So, the technology can incorporate improvements in successive releases.However, some groups have developed alternative Java-based technologies to try to address these deficiencies. This, in our judgment, is a mistake. Using a third-party tool like Apache Struts that augments JSP and servlet technology is a good idea when that tool adds sufficient benefit to compensate for the additional complexity. But using a nonstandard tool that tries to replace JSP is a bad idea. When choosing a technology, you need to weigh many factors: standardization, portability, integration, industry support, and technical features. The arguments for JSP alternatives have focused almost exclusively on the technical features part. But portability, standardization, and integration are also very important. For example, the servlet and JSP specifications define a standard directory structure for Web applications and provide standard files (.war files) for deploying Web applications. All JSP-compatible servers must support these standards. Filters can be set up to apply to any number of servlets or JSP pages, but not to nonstandard resources. The same goes for Web application security settings.Besides, the tremendous industry support for JSP and servlet technology results in improvements that mitigate many of the criticisms of JSP. For example, the JSP Standard Tag Library and the JSP 2.0 expression language address two of the most well-founded criticisms: the lack of good iteration constructs and the difficulty of accessing dynamic results without using either explicit Java code or verbose jsp:useBean elements.3. Misconceptions About JSPForgetting JSP Is Server-Side TechnologyHere are some typical questions Marty has received (most of them repeatedly).• Our server is running JDK 1.4. So, how do I put a Swing component in a JSP page?• How do I put an image into a JSP page? I do not know the proper Java I/O commands to read image files.• Since Tomcat does not support JavaScript, how do I make images that are highlighted when the user moves the mouse over them?• Our clients use older browsers that do not understand JSP. What should we do?• When our clients use "View Source" in a browser, how can I prevent them from seeing theJSP tags?All of these questions are based upon the assumption that browsers know something about the server-side process. But they do not. Thus:• For putting applets with Swing components into Web pages, what matters is the browser's Java version—the server's version is irrelevant. If the browser supports the Java 2 platform, you use the normal APPLET (or Java plug-in) tag and would do so even if you were using non-Java technology on the server.• You do not need Java I/O to read image files; you just put the ima ge in the directory for Web resources (i.e., two levels up from WEB-INF/classes) and output a normal IMG tag.• You create images that change under the mouse by using client-side JavaScript, referenced with the SCRIPT tag; this does not change just because the server is using JSP.• Browsers do not "support" JSP at all—they merely see the output of the JSP page. So, make sure your JSP outputs HTML compatible with the browser, just as you would do with static HTML pages.• And, of course you need not do anyt hing to prevent clients from seeing JSP tags; those tags are processed on the server and are not part of the output that is sent to the client. Confusing Translation Time with Request TimeA JSP page is converted into a servlet. The servlet is compiled, loaded into the server's memory, initialized, and executed. But which step happens when? To answer that question, remember two points:• The JSP page is translated into a servlet and compiled only the first time it is accessed after having been modified.• Loading into memory, initialization, and execution follow the normal rules for servlets.The most frequently misunderstood entries are highlighted. When referring to the table, note that servlets resulting from JSP pages use the _jspService method (called for both GET and POST requests), not doGet or doPost. Also, for initialization, they use the jspInit method, not the init method.JSP page translated into servlet Servlet compiled Servlet loaded into server's memory jspInit called _jspService called.4.What are application frameworks:A framework is a reusable, semi-complete application that can be specialized to produce custom applications [Johnson]. Like people, software applications are more alike than they are different. They run on the same computers, expect input from the same devices, output to the same displays, and save data to the same hard disks. Developers working on conventional desktop applications are accustomed to toolkits and development environments that leverage the sameness between applications. Application frameworks build on this common ground toprovide developers with a reusable structure that can serve as the foundation for their own products.A framework provides developers with a set of backbone components that have the following characteristics:1.They are known to work well in other applications.2. They are ready to use with the next project.3. They can also be used by other teams in the organization.Frameworks are the classic build-versus-buy proposition. If you build it, you will understand it when you are done—but how long will it be before you can roll your own? If you buy it, you will have to climb the learning curve—and how long is that going to take? There is no right answer here, but most observers would agree that frameworks such as Struts provide a significant return on investment compared to starting from scratch, especially for larger projects.Other types of frameworks:The idea of a framework applies not only to applications but to application componentsas well. Throughout this article, we introduce other types of frameworks that you can use with Struts. These include the Lucene search engine, the Scaffold toolkit, the Struts validator, and the Tiles tag library. Like application frameworks, these tools provide semi-complete versions of a subsystem that can be specialized to provide a custom component.Some frameworks have been linked to a proprietary development environment. This is not the case with Struts or any of the other frameworks shown in this book. You can use any development environment with Struts: Visual Age for Java, JBuilder, Eclipse, Emacs, and Textpad are all popular choices among Struts developers. If you can use it with Java, you can use it with Struts.Enabling technologies:Applications developed with Struts are based on a number of enabling technologies.These components are not specific to Struts and underlie every Java web application. A reason that developers use frameworks like Struts is to hide the nasty details behind acro nyms like HTTP, CGI, and JSP. As a Struts developer, you don’t need to be an alphabet soup guru, but a working knowledge of these base technologies can help you devise creative solutions to tricky problems.Hypertext Transfer Protocol (HTTP):When mediating talks between nations, diplomats often follow a formal protocol.Diplomatic protocols are designed to avoid misunderstandings and to keep negotiationsfrom breaking down. In a similar vein, when computers need to talk, they also follow a formal protocol. The protocol defines how data is transmitted and how to decode it once it arrives. Web applications use the Hypertext Transfer Protocol (HTTP) to move data between the browser running on your computer and the application running on the server.Many server applications communicate using protocols other than HTTP. Some of these maintain an ongoing connection between the computers. The application server knows exactly who is connected at all times and can tell when a connection is dropped. Because they know the state of each connection and the identity of each person using it, these are known as stateful protocols.By contrast, HTTP is known as a stateless protocol. An HTTP server will accept any request from any client and will always provide some type of response, even if the response is just to say no. Without the overhead of negotiating and retaining a connection, stateless protocols can handle a large volume of requests. This is one reason why the Internet has been able to scale to millions of computers.Another reason HTTP has become the universal standard is its simplicity. An HTTP request looks like an ordinary text document. This has made it easy for applications to make HTTP requests. You can even send an HTTP request by hand using a standard utility such as Telnet. When the HTTP response comes back, it is also in plain text that developers can read.The first line in the HTTP request contains the method, followed by the locationof the requested resource and the version of HTTP. Zero or more HTTP request headers follow the initial line. The HTTP headers provide additional information to the server. This can include the browser type and version, acceptable document types, and the browser’s cookies, just to name a few. Of the seven request methods, GET and POST are by far the most popular.Once the server has received and serviced the request, it will issue an HTTP response. The first line in the response is called the status line and carries the HTTP protocol version, a numeric status, and a brief description of the status. Following the status line, the server will return a set of HTTP response headers that work in a way similar to the request headers.As we mentioned, HTTP does not preserve state information between requests.The server logs the request, sends the response, and goes blissfully on to the next request. While simple and efficient, a stateless protocol is problematic for dynamic applications that need to keep track of their users. (Ignorance is not always bliss.Cookies and URL rewriting are two common ways to keep track of users between requests. A cookie is a special packet of information on the user’s computer. URL rewriting stores a special reference in the page address that a Java server can use to track users. Neither approach is seamless, and using either means extra work when developing a web application.On its own, a standard HTTP web server does not traffic in dynamic content. It mainly uses the request to locate a file and then returns that file in the response. The file is typically formatted using Hypertext Markup Language (HTML) [W3C, HTML] that the web browser can format and display. The HTML page often includes hypertext links to other web pages and may display any number of other goodies, such as images and videos. The user clicks a link to make another request, and the process begins a new.Standard web servers handle static content and images quite well but need a helping hand to provide users with a customized, dynamic response.DEFINITION:Static content on the Web comes directly from text or data files, like HTML or JPEG files. These files might be changed from time to time, but they are not altered automatically when requested by a web browser. Dynamic content, on the other hand, is generated on the fly, typically in response to an individualized request from a browser.Common Gateway Interface (CGI):The first widely used standard for producing dynamic content was the Common Gateway Interface (CGI). CGI uses standard operating system features, such as environment variables and standard input and output, to create a bridge, or gateway, between the web server and other applications on the host machine. The other applications can look at the request sent to them by the web server and create a customized response.When a web serve r receives a request that’s intended for a CGI program, it runs that program and provides the program with information from the incoming request. The CGI program runs and sends its output back to the server. The web server then relays the response to the browser.CGI defines a set of conventions regarding what information it will pass as environment variables and how it expects standard input and output to be used. Like HTTP, CGI is flexible and easy to implement, and a great number of CGI-aware programs have been written.The main drawback to CGI is that it must run a new copy of the CGI-aware program for each request. This is a relatively expensive process that can bog down high-volume sites where thousands of requests are serviced per minute. Another drawback is that CGI programs tend to be platform dependent. A CGI program written for one operating system may not run on another.5. Java servlets:Sun’s Java Servlet platform directly addresses the two main drawbacks of CGI programs.First, servlets offer better performance and utilization of resources than conventional CGI programs. Second, the write-once, run-anywhere nature of Java means that servlets are portable between operating systems that have a Java Virtual Machine (JVM).A servlet looks and feels like a miniature web server. It receives a request and renders a response. But, unlike conventional web servers, the servlet application programming interface (API) is specifically designed to help Java developers create dynamic applications.The servlet itself is simply a Java class that has been compiled into byte code, like any other Java object. The servlet has access to a rich API of HTTP-specific services, but it is still just another Java object running in an application and can leverage all your other Java assets.To give conventional web servers access to servlets, the servlets are plugged into containers. The servlet container is attached to the web server. Each servlet can declare what URL patterns it would like to handle. When a request matching a registered pattern arrives, the web server passes the request to the container, and the container invokes the servlet.But unlike CGI programs, a new servlet is not created for each request. Once the container instantiates the servlet, it will just create a new thread for each request. Java threads are much less expensive than the server processes used by CGI programs. Once the servlet has been created, using it for additional requests incurs very little overhead. Servlet developers can use the init() method to hold references to expensive resources, such as database connections or EJB Home Interfaces, so that they can be shared between requests. Acquiring resources like these can take several seconds—which is longer than many surfers are willing to wait.The other edge of the sword is that, since servlets are multithreaded, servlet developers must take special care to be sure their servlets are thread-safe. To learn more about servlet programming, we recommend Java Servlets by Example, by Alan R. Williamson [Williamson]. The definitive source for Servlet information is the Java Servlet Specification [Sun, JST].6. JavaServer Pages:While Java servlets are a big step up from CGI programs, they are not a panacea. To generate the response, developers are still stuck with using println statements to render the HTML. Code that looks like:out.println("<P>One line of HTML.</P>");out.println("<P>Another line of HTML.</P>");is all too common in servlets that generate the HTTP response. There are libraries that can help you generate HTML, but as applications grow more complex, Java developers end up being cast into the role of HTML page designers.Meanwhile, given the choice, most project managers prefer to divide development teams into specialized groups. They like HTML designers to be working on the presentation while Java engineers sweat the business logic. Using servlets alone encourages mixing markup withbusiness logic, making it difficult for team members to specialize.To solve this problem, Sun turned to the idea of using server pages to combine scripting and templating technologies into a single component. To build Java Server Pages, developers start by creating HTML pages in the same old way, using the same old HTML syntax. To bring dynamic content into the page, the developer can also place JSP scripting elements on the page. Scripting elements are tags that encapsulate logic that is recognized by the JSP. You can easily pick out scripting elements on JSP pages by looking for code that begins with <% and ends with %>.To be seen as a JSP page, the file just needs to be saved with an extension of .jsp.When a client requests the JSP page, the container translates the page into a source code file for a Java servlet and compiles the source into a Java class file—just as you would do if you were writing a servlet from scratch. At runtime, the container can also check the last modified date of the JSP file against the class file. If the JSP file has changed since it was last compiled, the container will retranslate and rebuild the page all over again.Project managers can now assign the presentation layer to HTML developers, who then pass on their work to Java developers to complete the business-logic portion. The important thing to remember is that a JSP page is really just a servlet. Anything you can do with a servlet, you can do with a JSP.7. JavaBeans:JavaBeans are Java classes which conform to a set of design patterns that make them easier to use with development tools and other components.DEFINITION A JavaBean is a reusable software component written in Java. To qualify as a JavaBean, the class must be concrete and public, and have a noargument constructor. JavaBeans expose internal fields as properties by providing public methods that follow a consistent design pattern. Knowing that the property names follow this pattern, other Java classes are able to use introspection to discover and manipulate JavaBean properties.The JavaBean design patterns provide access to the bean’s internal state through two flavor s of methods: accessors are used to read a JavaBean’s state; mutators are used to change a JavaBean’s state.Mutators are always prefixed with lowercase token set followed by the property name. The first character in the property name must be uppercase. The return value is always void—mutators only change property values; they do not retrieve them. The mutator for a simple property takes only one parameter in its signature, which can be of any type. Mutators are often nicknamed setters after their prefix. The mutator method signature for a weight property of the type Double would be:public void setWeight(Double weight)A similar design pattern is used to create the accessor method signature. Accessor methods are always prefixed with the lowercase token get, followed by the property name. The first character in the property name must be uppercase. The return value will match the method parameter in the corresponding mutator. Accessors for simple properties cannot accept parameters in their method signature. Not surprisingly, accessors are often called getters.The accessor method signature for our weight property is：public Double getWeight()If the accessor returns a logical value, there is a variant pattern. Instead of using the lowercase token get, a logical property can use the prefix is, followed by the property name. The first character in the property name must be uppercase. The return value will always be a logical value—either boolean or Boolean. Logical accessors cannot accept parameters in their method signature.The boolean accessor method signature for an on property would bepublic boolean isOn()The canonical method signatures play an important role when working with Java- Beans. Other components are able to use the Java Reflection API to discover a JavaBean’s properties by looking for methods prefixed by set, is, or get. If a component finds such a signature on a JavaBean, it knows that the method can be used to access or change the bean’s properties.Sun introduced JavaBeans to work with GUI components, but they are now used with every aspect of Java development, including web applications. When Sun engineers developed the JSP tag extension classes, they designed them to work with JavaBeans. The dynamic data for a page can be passed as a JavaBean, and the JSP tag can then use the bean’s properties to customize the output.For more on JavaBeans, we highly recommend The Awesome Power of JavaBeans, by Lawrence H. Rodrigues [Rodrigues]. The definitive source for JavaBean information is the JavaBean Specification [Sun, JBS].Model 2:The 0.92 release of the Servlet/JSP Specification described Model 2 as an architecture that uses servlets and JSP pages together in the same application. The term Model 2 disappeared from later releases, but it remains in popular use among Java web developers.Under Model 2, servlets handle the data access and navigational flow, while JSP pages handle the presentation. Model 2 lets Java engineers and HTML developers each work on their own part of the application. A change in one part of a Model 2 application does not。
JSP技术发展历史中英文对照外文翻译文献
中英文对照外文翻译文献(文档含英文原文和中文翻译)THE TECHNIQUE DEVELOPMENT HISTORY OF JSPThe Java Server Pages( JSP) is a kind of according to web of the script plait distance technique, similar carries the script language of Java in the server of theNetscape company of server- side JavaScript( SSJS) and the Active Server Pages(ASP) of the Microsoft. JSP compares the SSJS and ASP to have bettercan expand sex, and it is no more exclusive than any factory or some one particular server of Web. Though the norm of JSP is to be draw up by the Sun company of,any factory can carry out the JSP on own system. The After Sun release the JS P( the Java Server Pages) formally, the this kind of new Web application development technique very quickly caused the people's concern. JSP provided a special development environment for the Web application that establishes the high dynamic state. According to the Sun parlance, the JSP can adapt to include the Apache WebServer, IIS4.0 on the market at inside of 85% server product.This chapter will introduce the related knowledge of JSP and Databases,and JavaBean related contents, is all certainly rougher introduction among them basic contents, say perhaps to is a Guide only, if the reader needs the more detailed information, pleasing the book of consult the homologous JSP.1.1 GENER ALIZEThe JSP(Java Server Pages) is from the company of Sun Microsystems initiate, the many companies the participate to the build up the together of the a kind the of dynamic the state web the page technique standard, the it have the it in the construction the of the dynamic state the web page the strong but the do not the especially of the function. JSP and the technique of ASP of the Microsoft is very alike. Both all provide the ability that mixes with a certain procedure code and is explain by the language engine to carry out the procedure code in the code of HTML. Underneath we are simple of carry on the introduction to it. JSP pages are translated into servlets. So, fundamentally, any task JSP pages can perform could also be accomplished by servlets. However, this underlying equivalence does not mean that servlets and JSP pages are equally appropriate in all scenarios. The issue is not the power of the technology, it is the convenience, productivity, and maintainability of one or the other. After all, anything you can do on a particular computer platform in the Java programming language you could also do in assembly language. But it still matters which you choose.JSP provides the following benefits over servlets alone:• It is easier to write and maintain the HTML. Your static code is ordinary HTML: no extra backslashes, no double quotes, and no lurking Java syntax. • You can use standard Web-site development tools. Even HTML tools that know nothing about JSP can be used because they simply ignore the JSP tags. • You can divide up your development team. The Java programmers can work on the dynamic code. The Web developers can concentrate on the presentation layer. On large projects, this division is very important. Depending on the size of your team and the complexity of your project, you can enforce a weaker or stronger separation between the static HTML and the dynamic content.Now, this discussion is not to say that you should stop using servlets and use only JSP instead. By no means. Almost all projects will use both. For some requests in your project, you will use servlets. For others, you will use JSP. For still others, you will combine them with the MVC architecture . You want theapGFDGpropriate tool for the job, and servlets, by themselves, do not complete your toolkit.1.2 SOURCE OF JSPThe technique of JSP of the company of Sun, making the page of Web develop the personnel can use the HTML perhaps marking of XML to design to turn the end page with format. Use the perhaps small script future life of marking of JSP becomes the dynamic state on the page contents.( the contents changes according to the claim of)The Java Servlet is a technical foundation of JSP, and the large Web applies the development of the procedure to need the Java Servlet to match with with the JSP and then can complete, this name of Servlet comes from the Applet, the local translation method of now is a lot of, this book in order not to misconstruction, decide the direct adoption Servlet but don't do any translation, if reader would like to, can call it as" small service procedure". The Servlet is similar to traditional CGI, ISAPI, NSAPI etc. Web procedure development the function of the tool in fact, at use the Java Servlet hereafter, the customer need not use again the lowly method of CGI of efficiency, also need not use only the ability come to born page of Web of dynamic state in the method of API that a certain fixed Web server terrace circulate. Many servers of Web all support the Servlet, even not support the Servlet server of Web directly and can also pass the additional applied server and the mold pieces to support the Servlet. Receive benefit in the characteristic of the Java cross-platform, the Servlet is also a terrace irrelevant, actually, as long as match the norm of Java Servlet, the Servlet is complete to have nothing to do with terrace and is to have nothing to do with server of Web. Because the Java Servlet is internal to provide the service by the line distance, need not start a progress to the each claimses, and make use of the multi-threading mechanism can at the same time for several claim service, therefore the efficiency of Java Servlet is very high.But the Java Servlet also is not to has no weakness, similar to traditional CGI, ISAPI, the NSAPI method, the Java Servlet is to make use of to output the HTML language sentence to carry out the dynamic state web page of, if develop the whole website with the Java Servlet, the integration process of the dynamic state part and the static state page is an evil-foreboding dream simply. For solving this kind of weakness of the Java Servlet, the SUN released the JSP.A number of years ago, Marty was invited to attend a small 20-person industry roundtable discussion on software technology. Sitting in the seat next to Martywas James Gosling, inventor of the Java programming language. Sitting several seats away was a high-level manager from a very large software company in Redmond, Washington. During the discussion, the moderator brought up the subject of Jini, which at that time was a new Java technology. The moderator asked the manager what he thought of it, and the manager responded that it was too early to tell, but that it seemed to be an excellent idea. He went on to say that they would keep an eye on it, and if it seemed to be catching on, they would follow his company's usual "embrace and extend" strategy. At this point, Gosling lightheartedly interjected "You mean disgrace and distend."Now, the grievance that Gosling was airing was that he felt that this company would take technology from other companies and suborn it for their own purposes. But guess what? The shoe is on the other foot here. The Java community did not invent the idea of designing pages as a mixture of static HTML and dynamic code marked with special tags. For example, Cold Fusion did it years earlier. Even ASP (a product from the very software company of the aforementioned manager) popularized this approach before JSP came along and decided to jump on the bandwagon. In fact, JSP not only adopted the general idea, it even used many of the same special tags as ASP did.The JSP is an establishment at the model of Java servlets on of the expression layer technique, it makes the plait write the HTML to become more simple.Be like the SSJS, it also allows you carry the static state HTML contents and servers the script mix to put together the born dynamic state exportation. JSP the script language that the Java is the tacit approval, however, be like the ASP and can use other languages( such as JavaScript and VBScript), the norm of JSP also allows to use other languages.1.3JSP CHARACTERISTICSIs a service according to the script language in some one language of the statures system this kind of discuss, the JSP should be see make is a kind of script language. However, be a kind of script language, the JSP seemed to be too strong again, almost can use all Javas in the JSP. Be a kind of according to text originally of, take manifestation as the central development technique, the JSP provided all advantages of the Java Servlet, and, when combine with a JavaBeans together, providing a kind of make contents and manifestation that simple way that logic separate. Separate the contents and advantage of logical manifestations is, the personnel who renews the page external appearance neednot know the code of Java, and renew the JavaBeans personnel also need not be design the web page of expert in hand, can use to take the page of JavaBeans JSP to define the template of Web, to build up a from have the alike external appearance of the website that page constitute. JavaBeans completes the data to provide, having no code of Java in the template thus, this means that these templates can be written the personnel by a HTML plait to support. Certainly, can also make use of the Java Servlet to control the logic of the website, adjust through the Java Servlet to use the way of the document of JSP to separate website of logic and contents.Generally speaking, in actual engine of JSP, the page of JSP is the edit and translate type while carry out, not explain the type of. Explain the dynamic state web page development tool of the type, such as ASP, PHP3 etc., because speed etc. reason, have already can't satisfy current the large electronic commerce needs appliedly, traditional development techniques are all at to edit and translate the executive way change, such as the ASP → ASP+;PHP3 → PHP4.In the JSP norm book, did not request the procedure in the JSP code part( be called the Scriptlet) and must write with the Java definitely. Actually, have some engines of JSP are adoptive other script languages such as the EMAC- Script, etc., but actually this a few script languages also are to set up on the Java, edit and translate for the Servlet to carry out of. Write according to the norm of JSP, have no Scriptlet of relation with Java also is can of, however, mainly lie in the ability and JavaBeans, the Enterprise JavaBeanses because of the JSP strong function to work together, so even is the Scriptlet part not to use the Java, edit and translate of performance code also should is related with Java.1.4JSP MECHANISMTo comprehend the JSP how unite the technical advantage that above various speak of, come to carry out various result easily, the customer must understand the differentiation of" the module develops for the web page of the center" and" the page develops for the web page of the center" first.The SSJS and ASP are all in several year ago to release, the network of that time is still very young, no one knows to still have in addition to making all business, datas and the expression logic enter the original web page entirely heap what better solve the method. This kind of model that take page as the center studies and gets the very fast development easily. However, along with change of time, the people know that this kind of method is unwell in set up large, the Web thatcan upgrade applies the procedure. The expression logic write in the script environment was lock in the page, only passing to shear to slice and glue to stick then can drive heavy use. Express the logic to usually mix together with business and the data logics, when this makes be the procedure member to try to change an external appearance that applies the procedure but do not want to break with its llied business logic, apply the procedure of maintenance be like to walk the similar difficulty on the eggshell. In fact in the business enterprise, heavy use the application of the module already through very mature, no one would like to rewrite those logics for their applied procedure.HTML and sketch the designer handed over to the implement work of their design the Web plait the one who write, make they have to double work- Usually is the handicraft plait to write, because have no fit tool and can carry the script and the HTML contents knot to the server to put together. Chien but speech, apply the complexity of the procedure along with the Web to promote continuously, the development method that take page as the center limits sex to become to get up obviously.At the same time, the people always at look for the better method of build up the Web application procedure, the module spreads in customer's machine/ server the realm. JavaBeans and ActiveX were published the company to expand to apply the procedure developer for Java and Windowsto use to come to develop the complicated procedure quickly by" the fast application procedure development"( RAD) tool. These techniques make the expert in the some realm be able to write the module for the perpendicular application plait in the skill area, but the developer can go fetch the usage directly but need not control the expertise of this realm.Be a kind of take module as the central development terrace, the JSP appeared. It with the JavaBeans and Enterprise JavaBeans( EJB) module includes the model of the business and the data logic for foundation, provide a great deal of label and a script terraces to use to come to show in the HTML page from the contents of JavaBeans creation or send a present in return. Because of the property that regards the module as the center of the JSP, it can drive Java and not the developer of Java uses equally. Not the developer of Java can pass the JSP label( Tags) to use the JavaBeans that the deluxe developer of Java establish. The developer of Java not only can establish and use the JavaBeans, but also can use the language of Java to come to control more accurately in the JSP page according to the expression logic of the first floor JavaBeans. See now how JSPis handle claim of HTTP. In basic claim model, a claim directly was send to JSP page in. The code of JSP controls to carry on hour of the logic processing and module of JavaBeanses' hand over with each other, and the manifestation result in dynamic state bornly, mixing with the HTML page of the static state HTML code. The Beans can be JavaBeans or module of EJBs. Moreover, the more complicated claim model can see make from is request other JSP pages of the page call sign or Java Servlets.The engine of JSP wants to chase the code of Java that the label of JSP, code of Java in the JSP page even all converts into the big piece together with the static state HTML contents actually. These codes piece was organized the Java Servlet that customer can not see to go to by the engine of JSP, then the Servlet edits and translate them automatically byte code of Java.Thus, the visitant that is the website requests a JSP page, under the condition of it is not knowing, an already born, the Servlet actual full general that prepared to edit and translate completes all works, very concealment but again and efficiently. The Servlet is to edit and translate of, so the code of JSP in the web page does not need when the every time requests that page is explain. The engine of JSP need to be edit and translate after Servlet the code end is modify only once, then this Servlet that editted and translate can be carry out. The in view of the fact JSP engine auto is born to edit and translate the Servlet also, need not procedure member begins to edit and translate the code, so the JSP can bring vivid sex that function and fast developments need that you are efficiently.Compared with the traditional CGI, the JSP has the equal advantage. First, on the speed, the traditional procedure of CGI needs to use the standard importation of the system to output the equipments to carry out the dynamic state web page born, but the JSP is direct is mutually the connection with server. And say for the CGI, each interview needs to add to add a progress to handle, the progress build up and destroy by burning constantly and will be a not small burden for calculator of be the server of Web. The next in order, the JSP is specialized to develop but design for the Web of, its purpose is for building up according to the Web applied procedure, included the norm and the tool of a the whole set. Use the technique of JSP can combine a lot of JSP pages to become a Web application procedure very expediently.JSP的技术发展历史Java Server Pages(JSP)是一种基于web的脚本编程技术，类似于网景公司的服务器端Java脚本语言——server-side JavaScript(SSJS)和微软的Active Server Pages(ASP)。
外文翻译--JSP及其WEB技术
外文翻译原文及译文JSP and WEB technolog1 JSP IntroductionJSP (JavaServer Pages) is a Java-based scripting technology. Is advocated by Sun Microsystems Inc., together with a number of companies involved in the establishment of a dynamic web page technology standards. JSP technology is somewhat similar to ASP technology, It is a traditional HTML page file (*. htm, *. html) to insert Java program segment (Scriptlet) and JSP tag (tag), To form the JSP file（*jsp）. Web development with JSP is a cross-platform applications that can run under Linux, but also in other operating systems. In the JSP of the many advantages, one of which is that it will be HTML encoded Web page from the business logic separated effectively. JSP access with reusable components, such as Servlet, JavaBean and Java-based Web applications. JSP also supports directly in the Web page embedded Java code. JSP can be used two ways to access documents: JSP documents sent by the browser request, the request sent to the Servlet. JSP technology uses Java programming language, XML-type tags and scriptlets, to have a package deal with the logic of dynamic pages. Page tags and scriptlets can also exist in the server access to the resources of the application logic. JSP logic and Web page design and display isolated and support reusable component-based design, Web-based applications more quickly and easily developed.The Web server when meets visits the JSP homepage the request, first carries out segment, will then carry out the result code to return together with JSP in the document HTML for the customer. The insertion Java segment may operate the database, again the directional homepage and so on, realizes the function which the establishment dynamic homepage needs. JSP and Java Servlet are the same, is in the server end execution, usually returns to this client side is a HTML text, therefore client side, so long as has the browser to be able to glance over.The JSP page is composed of the HTML code and the inserting Java code. The server in the page by the client side was requested that later will carry on processing to these Java code, will then produce the HTML page will return gives the client side the browser. Java Servlet is the JSP technology base, moreover the large-scale Web applicationprocedure's development needs Java Servlet and the JSP coordination can complete. JSP had the Java technology simply easy to use, complete object-oriented, had the platform independency, and safe reliable, mainly faced Internet's all characteristics.2 JSP computing techniqueTo carry on the dynamic website conveniently fast the development, JSP has made the improvement in the following several aspects, causes it to become builds the cross platform fast the dynamic website first choice plan.2.1 carries on the content production and the demonstration separatesWith the JSP technology, the Web page development personnel may use HTML or the XML marking design and the formatted final page, and uses the JSP marking or the tootsy produces on page's dynamic content originally. Production content's logic is sealed in marks and in the JavaBeans module, and ties up in the script, all scripts in server end movement. Because core logic is sealed in marks and in JavaBeans, therefore the Web administrative personnels and the page designer, can edit and use the JSP page, but does not affect the content the production. In the server end, the JSP engine explained that the JSP marking and the script, produce the content which requested, and (or XML) page's form transmits the result by HTML the browser. This both are helpful in the author protects own code, and can guarantee any based on the HTML Web browser's complete usability.2.2 may entrust with heavy responsibility the moduleThe overwhelming majority JSP page relies on may entrust with heavy responsibility, the cross platform module (JavaBeans or Enterprise the JavaBeans module) carries out complex processing which the application procedure requests. The development personnel can share and exchange the execution ordinary operation the module, or causes these modules uses for more users and the customer association. Has accelerated the overall development process based on module's method, and causes each kind of organization obtains balanced in their existing skill and in the optimized result development endeavor.2.3 uses markingThe Web page development personnel will not be the familiar script language programmers. The JSP technology has sealed many functions, these functions are easy touse, marking to carry on the dynamic content production with JSP in the related XML to need. The standard JSP marking can visit and the instantiation JavaBeans module, the establishment or the retrieval module attribute, downloads Applet, as well as the execution difficulty with codes and the time-consuming function with other methods.2.4 adapts the platformNearly all platforms support Java, JSP+JavaBeans to be possible to pass unimpeded nearly under all platforms. Transplants from a platform to other platform, JSP and JavaBeans does not even need to translate, because the Java byte code is standard has nothing to do with the platform.2.5 database connectionIn Java connects the database the technology is the JDBC, Java procedure is connected through the JDBC driver and the database, operations and so on execution inquiry, extraction data. Sun Corporation has also developed JDBC-ODBC bridge, uses this technical Java procedure to be possible to visit has the ODBC driver database, at present the majority database systems have the ODBC driver, therefore the Java procedure can visit such as Oracle, Sybase, MS SQL Server and databases and so on MS Access. In addition, through the development marking storehouse, the JSP technology may further expand. The third party development personnel and other personnel may found their marking storehouse for the commonly used function. This enables the Web page development personnel to be able to use the familiar tool and to be similar to marking same carries out the specific function component to carry on the work. The JSP technology very easy conformity to many kinds of application architecture, to use the extant tool and the skill, and can expand to the support enterprise distributional application.3 Eclipse function synopsisMore and more Java development personnel already started the productivity which and the quality income appreciates Eclipse JDT to provide. It was the Java editor provides grammar Gao Liang to demonstrate that the formatting, the fold, the content were auxiliary, code template and so on many functions. It grows unceasingly available restructuring and the code generation function set permits you in a higher rank the operation code, and automated usual code intensity duty and easy wrong duty. Moreover, in develops the codeand uses JDT to compile and to carry out the JUnit test built-in support carries on the unit testing after the code, may use Eclipse the first-class Java debugger debugging when the movement meets any question. Besides JDT, Eclipse SDK- the most popular downloading - also contains Plug-in Development Environment(PDE). PDE used the specific function to expand JDT to construct the Eclipse plug-in unit - based on the Eclipse application procedure basic construction agglomeration. In fact, uses the tool which provides by Eclipse itself to be able to surmount the Java development, may expand the existing Eclipse application procedure, or even founds the brand-new application procedure.Eclipse by a script level constitution, contains in many functional modules or the Eclipse terminology so-called “the plug-in unit”. The plug-in unit is provides all functions in the Eclipse application procedure the module. They cooperate through its API to pay the final outcome together. In Eclipse, even the most foundation's function, for instance the search and the start installment's plug-in unit, seals in the plug-in unit. In order to expand the existing Eclipse function or carry on the construction in above, the plug-in unit the concrete expansion contribution for the expansion spot which will expose by other plug-in units. Usually, the plug-in unit concentrates the specific region responsibility, and gives through or a many expansion way other responsibility designation other plug-in units. For example, a plug-in unit allows you parallel to compare two documents visibly the contents, but it will not care how to read these documents even how to explain these document structure; This is other plug-in unit's work. When compared with two documents, this plug-in unit first inspects whether to have another plug-in unit to be possible to explain these document structure. If found one, it to the plug-in unit inquiry related file organization information which found, and used this information in the comparison process.May see that the modular construction was Eclipse has provided the huge flexibility, and provided one to be possible to support the massive application procedure platform which the original design has not expected.4 Structs function synopsisStruts is a MVC frame (Framework), uses in developing Java fast the Web application. Struts realizes the key point in C(Controller), Action which and we have custom-madeincluding ActionServlet/RequestProcessor, was also V(View) provides a series of rows to have custom-made the label (Custom Tag). Spring is a light vessel (light-weight container), its core is the Bean factory (Bean Factory), with constructs M(Model) which we need. Above this foundation, Spring has provided AOP (Aspect-Oriented Programming, face stratification plane programming) realization, provides under the non-management environment with it to declare services and so on way business, security; Is more convenient to Bean factory expansion ApplicationContext we to realize the J2EE application; DAO/ORM realizes facilitates us to carry on the database the development; Web MVC and Spring Web have provided Java the Web application frame or carries on the integration with other popular Web frame. That is may a both use, achieve both own characteristic carries on supplementary.Structs is the kind which, servlet and the JSP mark a group cooperates mutually, they compose the MVC 2 designs which may entrust with heavy responsibility. This definition expressed that Struts is a frame, but is not a storehouse, but Struts has also contained the rich mark storehouse and the independence in this frame work utility program class.Client browser (customer browser), the request founds an event from customer browser's each HTTP. The Web vessel will use a HTTP response to make the response.Controller (controller), the controller receive from browser's request, and decided that sends out where this request. Speaking of Struts, the controller is an order design pattern which realizes by servlet. struts-config.xml document disposition controller.Service logic, the service logic renewal model's condition, and helps the control application procedure the flow. Speaking of Struts, this is through takes the actual service logic “thin” the packing Action kind to complete.Model (model) condition, model expression application procedure condition. Service object renewal application procedure condition. ActionForm bean in conversation level or request level expression model condition, but is not in the lasting level. The JSP document uses JSP to mark the read from the ActionForm bean information.View (view), the view is a JSP document. And does not have the flow logic, does not have the service logic, also does not have the model information -- Only then marks. The mark causes Struts is different with other frames (for example Velocity) one of factors.Just like the Struts controller is (event usually is HTTP post) maps the event kind of servlet. you to expect - the air-operated controller use configuration files to cause you notto need to carry on to these values the hard code. The time has changed, but method as before.The Action kind, ActionForm maintains the Web application procedure the conversation condition. ActionForm is one abstract class, must found this kind of subclass for each input form model. When I said when input form model, what refers to the ActionForm expression is establishes or in the renewal general sense data by the HTML form.The Action kind is service logic packing. A Action kind of use is transforms HttpServletRequest into the service logic. Must use Action, please found its subclass and covers process () the method.ActionServlet (Command) will use perform () the method the parametrization kind to transmit for ActionForm. Still did not have too many repugnant request.getParameter () to transfer. When the event progresses to this step, the input form data (or HTML form data) has been withdrawn from the request class and shifts to the ActionForm kind.Considered that a Action kind of another way is the Adapter design pattern. The Action use will be “a kind of connection will transform another connection which will need for the client. Adapter enables the kind the joint operation, if does not have Adapter, then these kinds will be unable because of the incompatible connection the joint operation.”.In this example's client is ActionServlet, it knows nothing about to our concrete service class connection. Therefore, Struts has provided a service connection which it can understand, namely Action. Through expands Action, we cause our service connection and the Struts service connection maintain compatible.5 CSS synopsisThe CSS edition method is the same with HTML, may also be any text editor or the homepage edition software, but also has uses for to edit CSS specially the software. If you write the CSS sentence regards the exterior cascading style sheet, but transfers in the HTML document, then its extension saves .css to be possible. Initially the technical personnel found out HTML, mainly stresses on the definition content, for instance expressed that a paragraph, indicates the title, but excessively has not designed HTML the typesetting and the contact surface effect.Along with the Internet rapid development, HTML is widely applied, the surfer people hoped certainly that the homepage makes attractive, therefore the HTMLtypesetting and the contact surface effect's limitation exposes day by day. In order to solve this problem, the people also took many tortuous paths, has used some not good method, for instance increases many attribute results to HTML becomes the code very extremely fat, turns the picture the text, excessively many comes the typesetting using Table, expresses the white space with the blank picture and so on. Appears until CSS.CSS may be a homepage design breakthrough, it has solved the homepage contact surface typesetting difficult problem. May such say that HTML Tag is mainly defines the homepage content (Content), but CSS decided how these homepage content does demonstrate (Layout). The CSS English is Cascading Style Sheets, Chinese may translate the tandem cascading style sheet. CSS may divide into three kinds according to its position: In inlays the style (Inline Style), internal cascading style sheet (Internal Style Sheet), exterior cascading style sheet (External Style Sheet).6 HTML function synopsisHyper Text Markup the Language hypertext mark language is one kind uses for to manufacture the hypertext documents the simple mark language. The hypertext documents which compiles with HTML are called the HTML documents, it can the independence in each kind of operating system platform (for example UNIX, WINDOWS and so on). HTML has served as since 1990 on World Wide Web the information to express the language, uses in describing the Homepage form design and it and on WWW the other Homepage linked information.The HTML documents (i.e. the Homepage source document) was one has laid aside the mark ASCII text document, usually it had .html or the .htm document extension. Produces HTML documents mainly to have the following three ways: 1. the manual direct compilation (e.g. ASCII text editor which or other HTML edition tool likes with you). 2. will have other form documents through certain format conversion tool (for example the WORD documents) to transform the HTML documents. 3. by the Web server (or said that the HTTP server) one only then real-time dynamic produces. the HTML language is through uses each kind of mark (tags) to mark the documents the structure as well as marks the ultra chain (Hyperlink) the information.Although the HTML language described the documents structure form, but how can't define the documents information to precisely demonstrate and arrange, but is onlysuggested how the Web browser (for example Mosiac, Netscape and so on) should demonstrate and arrange these information, is decided finally in front of user's demonstration result by the Web browser's demonstration style and to the mark explanatory ability. Why is the identical documents the effect which demonstrated in the different browser meets is dissimilar. At present the HTML language's edition is 2.0, it is based on SGML (Standard Generalized Markup Language, standard sets at sign language generally, as soon as is applies mechanically describes digitized documents structure and manages its content complex standard) a subset to evolve comes. Although in next edition's standard HTML3.0 (is also called HTML+) to draw up, but some the partial experimental nature draft standard widely has been used, the mostly outstanding Web browser (for example Netscape and so on) can explain in the HTML3.0 part new mark, therefore introduced in this chapter some HTML3.0 new mark has been accepted by the most browsers.7 Js script language synopsisJS is javascrip, Javascript is one kind the script language which comes by the Netscape LiveScript development, the main purpose is to solve the server terminal language, for instance Perl, carry-over speed question. At that time served the end to need to carry on the confirmation to the data, because the network speed was quite slow, only then 28.8kbps, the confirmation step waste's time were too many. Therefore Netscape browser Navigator has joined Javascript, has provided the data confirmation basic function.The JavaScript official name is “ECMAScript”. This standard by ECMA organizat ion development and maintenance. ECMA-262 is the official JavaScript standard. This standard based on JavaScript (Netscape) and JScript (Microsoft). Netscape (Navigator 2.0) Brendan Eich has invented this language, started from 1996, already appeared in all Netscape and in the Microsoft browser. The ECMA-262 development began in 1996, in 1997 July, the ECMA general meeting has accepted its first edition.Script script uses one specific descriptive language, rests on certain form compilation to be possible the execution document, is also called as great or the batch run document. The script usually may transfer temporarily by the application procedure and carry out. Each kind of script present widely is applied in the homepage design, because the script not only may reduce the homepage the scale and raises the homepage browsing speed,moreover may enrich the homepage performance, like animation, sound and so on. Cites a most common example, when we click in the homepage the E-mail address can transfer Outlook Express or the Foxmail this kind of mail software automatically, is realizes through the script function. Also because of script these characteristics, the human who harbors ulterior motives by some are often using. For example joins some destruction computer system's order in the script, like this works as the user browsing homepage, once transfers this kind of script, will then cause the user the system to come under the attack. Therefore the user should act according to visits homepage the trust degree selective security rank, specially regarding these itself content on the illegal homepage, do not permit the use script easily. Through “the safe establishment” the dialog box, the choice “the script” under option each kind of establishment may with ease re alize to script being forbid and begins using.Present's script language is quite many, script language execution generally only with concrete explanation actuator related, so long as therefore on the system has the corresponding language interpreter to be possible to achieve the cross platform. Script (Script), is includes order and so on bind and alias sets, you may save this set are an independent document then in the time which needs carries out, like this may facilitate you in the CS use. The script may save for the suffix named .cfg document places under the cstrike folder, when execution in control bench input: exec (script filename) .cfg then. For instance saves a script is the buys.cfg document, inputs in the control bench: execbuys.cfg may realize the function which we need. Must realize an order, so long as is good this process definition (alias), and assigns a key position for this order, so long as later according to will assign the good key position, may realize this proce沈阳航空航天大学毕业设计（论文）外文翻译——译文JSP及其WEB技术. 1 JSP简介JSP（JavaServer Pages）是一种基于Java的脚本技术。
JSP技术英文简介
Introduction of JSP TechnologyJavaServer PagesTM (jsp (SUN enterprise application of choice)) technology for the creation of display content dynamically generated Web page provides a simple and rapid method. jsp (SUN enterprise application of choice) technology is designed to enable structure-based Web applications more easily and faster, and can these applications with a variety of Web servers, application servers, browsers, and development tools to work together.Here provides a jsp (SUN enterprise application of choice) technology overview, describes the background of its development, as well as the overall objective of this technology. At the same time, a simple example, also describes a JavaTM technology-based key component of the page. Web application development of JavaServer Pages technology WaysIn the development of jsp (SUN enterprise application of choice) specification process, Sun Microsystems (Sun Microsystems Inc.) And many major Web servers, application servers and development tools providers, as well as a variety of experienced development groups to cooperate. The result is found a page for applications and developers to balance the portability and ease of use of development methodologies.Will generate and display the contents of the separationUsing jsp technology, Web page developers can use HTML or xml logo to design and formatting the final page. Jsp logo or the use of bound feet would have to generate dynamic content on the page. The logic-generated content has been packaged in a logo and JavaBeans components and tied up in a small script, all the scripts in the server-side run. If the core logic was encapsulated in the logo and Beans, then other people, such as management and Web page designers, can edit and use jsp pages, without affecting the generation of content.The server side, jsp engine explained jsp logo and small script to generate the requested content (for example, by accessing JavaBeans components, the use of technology JDBCTM access the database, or include file), and the results to HTML (or xml) page of the form sent back to the browser. This helps the author to protect their code, and ensure that any HTML-based Web browser completely availability.Emphasis on reusable componentsJsp page relies on the vast majority of reusable, cross-platform components (JavaBeans or Enterprise JavaBeansTM components) to implement the requirements of applications more complex treatment. Developers to be able to share and exchange components to perform common operations, or make these components more user or client groups to use. Component-based approach to accelerate the overall development process, and make a variety of organizations in their existing skills and to optimize the results of development efforts in the balance.Used to simplify page development logoWeb page developers are not familiar with the scripting language of the programmer. JavaServer Page technology packages a number of functions, which are in use with the jsp-related xml logo in dynamic content generation needs. Jsp logo standards can access and instantiate JavaBeans components, set or retrieve components of property, download Applet, and implementation by other means more difficult to encode and time-consuming function.Through the development of customized logos library, jsp technology can be extended. In future, third-party developers and other personnel for commonly used features to create your ownlogo library. This allows Web page developers can use familiar tools and the same logo as the implementation of specific functions of components to work.jsp technology easily integrated into a variety of applications architecture, to take advantage of existing tools and techniques, and expanded to be able to support enterprise-class distributed applications. The use of Java technology as part of the family, as well as the Java 2 (Enterprise Architecture) is an integral part of, jsp technology can support the highly complex Web-based applications.Jsp page because of the built-scripting language is based on the Java programming language, and all the jsp pages are compiled to become Java Servlet, jsp page on with all the benefits of Java technology, including robust storage management and security.As part of Java Platform, jsp has a Java programming language, "write once, run everywhere" characteristics. As more and more suppliers will be added to jsp support their products, you can use your own choice of server and tools, change tools, or the server does not affect the current application.When used with Java 2 Platform, Enterprise Edition (J2EE) and Enterprise JavaBean technology integration, jsp page will provide enterprise-class scalability and performance, which is essential for the deployment of virtual enterprise Web-based applications is essential.jsp instructionsjsp page using jsp direct instruction delivered to the jsp engine. This includes:jsp page directives related to information transmission page, such as buffer and thread information or wrong treatment.Language instructions specified scripting language, as well as all the expansion.Contains instructions (in the above examples have shown) can be used in the page that contains an external document. A good example is the copyright or company information documents documents - in a centralized location to preserve the document and the page contains more than in all jsp page should be easier to update. Of course, being contained in a document may also be another jsp file.Logo library instructions pointed out that the page can call a client logo library.jsp logoWill deal with the overwhelming majority of jsp and jsp related xml based on the completion of the logo. jsp 1.0 contains substantial standard logo, which identifies as a core identity, including:jsp: useBean statement of the identity of a component instance of the use of JavaBeans. If the component instance does not exist, JavaBeans components to instantiate and register the logo.jsp: setProperty this logo set up examples of components of a property's value.jsp: getProperty this logo to obtain a component instance of the property value, will be translated into a string, and place it implied object "out" Medium.jsp:includejsp:forwardThe merit of their logo in the application easy to use and share. Grammar based on the logo of the real power comes from the customer identification library development, makes a tool supplier or other personnel can request a specific assignment to create and logo.Script componentsjsp page in the page that contains a small script, called the small script (scriptlets). Small scriptis a code fragment, in the request processing is executed. Small scripts can be a static page element (as the same as the above example) to create dynamically generated pages.Script in the <% and%> signs have been described. Signs in this for all the things are described scripting language engine implementation, in our case are the host of the Java Virtual Machinejsp specification support all commonly used script component, including regular expressions and statements.jsp page application modeljsp page from the implementation of js engine, engines installed in the Web server or application using jsp server. jsp engine to accept the client request to the jsp page, and generate jsp pages to the client's response.jsp pages are usually compiled become a Java Servlet. The latter is a standard Java extension in site has more detailed description. Page developers can access all of the Java application environment to take advantage of Java technology, scalability and portability.When the first jsp page is called, if it does not exist, will be compiled into a Java Servlet category, and is stored in the server's memory. This makes the next call to the page have a very quick response.jsp page can be included in a wide variety of application architecture or model. jsp page can be used by different protocols, components and format of the composition of the Commonwealth. The following sections describe some of the possible consequences.A simple applicationIn a simple implementation, the browser directly call jsp page, jsp page itself generate the requested content (may be called directly from the JDBC database access to information). jsp page can call the JDBC or Java BlendTM component to generate the results, and create a standard HTML, as a result sent back to the browser.The model is basically used jsp page (compilers become Java Servlet) instead of the concept of CGI-BIN. This method has the following advantages:Simple and fast programmingPage authors can easily and resources of state, upon request, to generate dynamic contentThis structure in many applications a good job, but should not be extended to a large number of concurrent Web-based customer access scarce corporate resources, since each client must be set up or share a resource that can be used to connect the content. For example, if the jsp page to access the database, may generate much connection to the database, which will affect the database performance.The use of a flexible Java Servlet ApplicationIn another possible configuration, Web-based client may be directly on the Java Servlet requests, Servlet to generate dynamic content, the results tied to a results object and call jsp page. jsp page to access the object from the dynamic content, and the results (such as HTML) sent back to the browser.This method to create more applications can be shared between reusable components and applications can be used as part of a bigger completed. However, in the same deal with databases such as Enterprise Resource Connection, the scalability problem still exists.JavaBean technology using enterprise-class scalability treatmentjsp page can be used as Enterprise JavaBean (EJB) architecture, a middle layer. In this case, jsp pages and the back-end resources through EJB components interact.EJB components on the back-end management of resources to visit, so as a large number of concurrent users with scalable performance. For e-commerce or other applications, EJB management transactions and potential safety. This will simplify the jsp page. The model for the Java 2 Enterprise Edition (J2EE) platform support.jsp page with the xml technology integrationjsp page can be used to generate the xml and the HTML page.For a simple xml generated, developers can include jsp page xml logo and part of the static template. Dynamic xml generation, the use of server-based objects and generate the output xml client identifier.jsp page with the xml tools are not incompatible. Although the Sun in the design specification when jsp page jsp makes even manual for creators is also very easy, jsp specification also provides a mechanism to facilitate the creation of an arbitrary jsp page xml version. In this way, xml tool to be able to create and operate jsp page.By jsp convert logo and components compatible with the xml equivalent, you can use xml-based tools to operate the jsp page. For example, the script can be included in the <% and%> in, or based on the xml logo <jsp:scriptlet> and </ jsp: scriptlet> Medium. In fact, after following a few simple jsp page will be converted to xml pages are possible, these steps include:Adding a root element jspComponents and instructions will be converted to xml and other objects of compatibleFor page in other components (usually non-jsp) create a CDATA elementThrough this method compatible with the xml, create HTML page designers still have a rapidly create dynamic Web pages-to-use environment, meanwhile, xml-based tools and services can be integrated with the jsp page and compatible server and jsp to work together.jsp technology's futurejsp technology has been designed as an open, scalable dynamic Web page set up standards. Developers can use jsp page to create a portable Web applications, in different Web and application servers for the different occasions are running, and whatever the occasion itself and the need for the creation of tools.Through cooperation with leaders of the industry, Sun assurance jsp norms are open and can be transplanted. Can use any client and server platforms, in any place to prepare and deploy them. The future, tools, suppliers and other vendors will be provided for the specialized function of the client logo library to expand the platform functionality.jsp specification version 1.0 is the path to the dynamic Web page generated by an open industry standard method of the first step. Version 1.0 through a core logo sets, implicit objects, and to start creating dynamic Web pages constitutes the basic functions required of the method is basic. Already has a number of Web servers, application server and development tool vendors are adding to their products jsp1.0 support, so that the industry already has the initial, immediate support. Will be completed later in 1999 the 1.1 version of the xml through greater support for identification of customers, as well as integration with J2EE and the expansion of this version. And suppliers may choose to extend and expand the specification in jsp basic, necessary function. jsp engine can support a variety of powerful scripting language and object model. In the industry to expand technological capabilities and the use of jsp at the same time, Sun also promised to guarantee jsp platform and server technology to maintain inter-inherent portability.This article comes from the original link WEB Development Network:。
计算机外文翻译---JSP应用框架
外文翻译原文及译文JSP application frameworksWhat are application frameworks:A framework is a reusable, semi-complete application that can be specialized toproduce custom applications [Johnson]. Like people, software applications are more alike than they are different. They run on the same computers, expect input from the same devices, output to the same displays, and save data to the same hard disks. Developers working on conventional desktop applications are accustomed to toolkits and development environments that leverage the sameness between applications. Application frameworks build on this common ground to provide developers with a reusable structure that can serve as the foundation for their own products.A framework provides developers with a set of backbone components that have the following characteristics:1.They are known to work well in other applications.2. They are ready to use with the next project.3. They can also be used by other teams in the organization.Frameworks are the classic build-versus-buy proposition. If you build it, you will understand it when you are done—but how long will it be before you can roll your own? If you buy it, you will have to climb the learning curve—and how long is that going to take? There is no right answer here, but most observers would agree that frameworks such as Struts provide a significant return on investment compared to starting from scratch, especially for larger projects.Other types of frameworks:The idea of a framework applies not only to applications but to application componentsas well. Throughout this article, we introduce other types of frameworks that you can use with Struts. These include the Lucene search engine, the Scaffold toolkit, the Struts validator, and the Tiles tag library. Like application frameworks, these tools providecomponent.Some frameworks have been linked to a proprietary development environment. This is not the case with Struts or any of the other frameworks shown in this book. You can use any development environment with Struts: Visual Age for Java, JBuilder, Eclipse, Emacs, and Textpad are all popular choices among Struts developers. If you can use it with Java, you can use it with Struts.Enabling technologies:Applications developed with Struts are based on a number of enabling technologies.These components are not specific to Struts and underlie every Java web application. A reason that developers use frameworks like Struts is to hide the nasty details behind acronyms like HTTP, CGI, and JSP. As a Struts developer, you don’t need to be an alphabet soup guru, but a working knowledge of these base technologies can help you devise creative solutions to tricky problems.Hypertext Transfer Protocol (HTTP):When mediating talks between nations, diplomats often follow a formal protocol.Diplomatic protocols are designed to avoid misunderstandings and to keep negotiations from breaking down. In a similar vein, when computers need to talk, they also follow a formal protocol. The protocol defines how data is transmitted and how to decode it once it arrives. Web applications use the Hypertext Transfer Protocol (HTTP) to move data between the browser running on your computer and the application running on the server.Many server applications communicate using protocols other than HTTP. Some of these maintain an ongoing connection between the computers. The application server knows exactly who is connected at all times and can tell when a connection is dropped. Because they know the state of each connection and the identity of each person using it, these are known as stateful protocols.By contrast, HTTP is known as a stateless protocol. An HTTP server will accept any request from any client and will always provide some type of response, even if the response is just to say no. Without the overhead of negotiating and retaining a connection, stateless protocols can handle a large volume of requests. This is one reason why theInternet has been able to scale to millions of computers.Another reason HTTP has become the universal standard is its simplicity. An HTTP request looks like an ordinary text document. This has made it easy for applications to make HTTP requests. You can even send an HTTP request by hand using a standard utility such as Telnet. When the HTTP response comes back, it is also in plain text that developers can read.The first line in the HTTP request contains the method, followed by the locationof the requested resource and the version of HTTP. Zero or more HTTP request headers follow the initial line. The HTTP headers provide additional information to the server. This can include the browser type and version, acceptable document types, and the browser’s cookies, just to name a few. Of the s even request methods, GET and POST are by far the most popular.Once the server has received and serviced the request, it will issue an HTTP response. The first line in the response is called the status line and carries the HTTP protocol version, a numeric status, and a brief description of the status. Following the status line, the server will return a set of HTTP response headers that work in a way similar to the request headers.As we mentioned, HTTP does not preserve state information between requests.The server logs the request, sends the response, and goes blissfully on to the next request. While simple and efficient, a stateless protocol is problematic for dynamic applications that need to keep track of their users. (Ignorance is not always bliss.Cookies and URL rewriting are two common ways to keep track of users between requests. A cookie is a special packet of information on the user’s computer. URL rewriting stores a special reference in the page address that a Java server can use to track users. Neither approach is seamless, and using either means extra work when developing a web application. On its own, a standard HTTP web server does not traffic in dynamic content. It mainly uses the request to locate a file and then returns that file in the response. The file is typically formatted using Hypertext Markup Language (HTML) [W3C, HTML] that the web browser can format and display. The HTML page often includes hypertext links to other web pages and may display any number of other goodies, such as images andvideos. The user clicks a link to make another request, and the process begins a new.Standard web servers handle static content and images quite well but need a helping hand to provide users with a customized, dynamic response.DEFINITION:Static content on the Web comes directly from text or data files, like HTML or JPEG files. These files might be changed from time to time, but they are not altered automatically when requested by a web browser. Dynamic content, on the other hand, is generated on the fly, typically in response to an individualized request from a browser.Common Gateway Interface (CGI):The first widely used standard for producing dynamic content was the Common Gateway Interface (CGI). CGI uses standard operating system features, such as environment variables and standard input and output, to create a bridge, or gateway, between the web server and other applications on the host machine. The other applications can look at the request sent to them by the web server and create a customized response.When a web server receives a request that’s intended for a CGI program, it runs that program and provides the program with information from the incoming request. The CGI program runs and sends its output back to the server. The web server then relays the response to the browser.CGI defines a set of conventions regarding what information it will pass as environment variables and how it expects standard input and output to be used. Like HTTP, CGI is flexible and easy to implement, and a great number of CGI-aware programs have been written.The main drawback to CGI is that it must run a new copy of the CGI-aware program for each request. This is a relatively expensive process that can bog down high-volume sites where thousands of requests are serviced per minute. Another drawback is that CGI programs tend to be platform dependent. A CGI program written for one operating system may not run on another.Java servlets:Sun’s Java Servlet platform directly addresses the two main drawbacks of CGIconventional CGI programs. Second, the write-once, run-anywhere nature of Java means that servlets are portable between operating systems that have a Java Virtual Machine (JVM).A servlet looks and feels like a miniature web server. It receives a request and renders a response. But, unlike conventional web servers, the servlet application programming interface (API) is specifically designed to help Java developers create dynamic applications.The servlet itself is simply a Java class that has been compiled into byte code, like any other Java object. The servlet has access to a rich API of HTTP-specific services, but it is still just another Java object running in an application and can leverage all your other Java assets.To give conventional web servers access to servlets, the servlets are plugged into containers. The servlet container is attached to the web server. Each servlet can declare what URL patterns it would like to handle. When a request matching a registered pattern arrives, the web server passes the request to the container, and the container invokes the servlet.But unlike CGI programs, a new servlet is not created for each request. Once the container instantiates the servlet, it will just create a new thread for each request. Java threads are much less expensive than the server processes used by CGI programs. Once the servlet has been created, using it for additional requests incurs very little overhead. Servlet developers can use the init() method to hold references to expensive resources, such as database connections or EJB Home Interfaces, so that they can be shared between requests. Acquiring resources like these can take several seconds—which is longer than many surfers are willing to wait.The other edge of the sword is that, since servlets are multithreaded, servlet developers must take special care to be sure their servlets are thread-safe. To learn more about servlet programming, we recommend Java Servlets by Example, by Alan R. Williamson [Williamson]. The definitive source for Servlet information is the Java Servlet Specification [Sun, JST].JavaServer Pages:While Java servlets are a big step up from CGI programs, they are not a panacea. To generate the response, developers are still stuck with using println statements to render the HTML. Code that looks like:out.println("<P>One line of HTML.</P>");out.println("<P>Another line of HTML.</P>");is all too common in servlets that generate the HTTP response. There are libraries that can help you generate HTML, but as applications grow more complex, Java developers end up being cast into the role of HTML page designers.Meanwhile, given the choice, most project managers prefer to divide development teams into specialized groups. They like HTML designers to be working on the presentation while Java engineers sweat the business logic. Using servlets alone encourages mixing markup with business logic, making it difficult for team members to specialize.To solve this problem, Sun turned to the idea of using server pages to combine scripting and templating technologies into a single component. To build Java Server Pages, developers start by creating HTML pages in the same old way, using the same old HTML syntax. To bring dynamic content into the page, the developer can also place JSP scripting elements on the page. Scripting elements are tags that encapsulate logic that is recognized by the JSP. You can easily pick out scripting elements on JSP pages by looking for code that begins with <% and ends with %>.To be seen as a JSP page, the file just needs to be saved with an extension of .jsp.When a client requests the JSP page, the container translates the page into a source code file for a Java servlet and compiles the source into a Java class file—just as you would do if you were writing a servlet from scratch. At runtime, the container can also check the last modified date of the JSP file against the class file. If the JSP file has changed since it was last compiled, the container will retranslate and rebuild the page all over again.Project managers can now assign the presentation layer to HTML developers, who then pass on their work to Java developers to complete the business-logic portion. The important thing to remember is that a JSP page is really just a servlet. Anything you can do with a servlet, you can do with a JSP.JavaBeans:JavaBeans are Java classes which conform to a set of design patterns that make them easier to use with development tools and other components.DEFINITION A JavaBean is a reusable software component written in Java. To qualify as a JavaBean, the class must be concrete and public, and have a noargument constructor. JavaBeans expose internal fields as properties by providing public methods that follow a consistent design pattern. Knowing that the property names follow this pattern, other Java classes are able to use introspection to discover and manipulate JavaBean properties.The JavaBean design patterns provide access to the bean’s internal stat e through two flavors of methods: accessors are used to read a JavaBean’s state; mutators are used to change a JavaBean’s state.Mutators are always prefixed with lowercase token set followed by the property name. The first character in the property name must be uppercase. The return value is always void—mutators only change property values; they do not retrieve them. The mutator for a simple property takes only one parameter in its signature, which can be of any type. Mutators are often nicknamed setters after their prefix. The mutator method signature for a weight property of the type Double would be:public void setWeight(Double weight)A similar design pattern is used to create the accessor method signature. Accessor methods are always prefixed with the lowercase token get, followed by the property name. The first character in the property name must be uppercase. The return value will match the method parameter in the corresponding mutator. Accessors for simple properties cannot accept parameters in their method signature. Not surprisingly, accessors are often called getters.The accessor method signature for our weight property is：public Double getWeight()If the accessor returns a logical value, there is a variant pattern. Instead of using the lowercase token get, a logical property can use the prefix is, followed by the property name.be a logical value—either boolean or Boolean. Logical accessors cannot accept parameters in their method signature.The boolean accessor method signature for an on property would bepublic boolean isOn()The canonical method signatures play an important role when working with Java- Beans. Other components are able to use the Java Reflec tion API to discover a JavaBean’s properties by looking for methods prefixed by set, is, or get. If a component finds such a signature on a JavaBean, it knows that the method can be used to access or change the bean’s properties.Sun introduced JavaBeans to work with GUI components, but they are now used with every aspect of Java development, including web applications. When Sun engineers developed the JSP tag extension classes, they designed them to work with JavaBeans. The dynamic data for a page can be passed as a JavaBean, and the JSP tag can then use the bean’s properties to customize the output.For more on JavaBeans, we highly recommend The Awesome Power of JavaBeans, by Lawrence H. Rodrigues [Rodrigues]. The definitive source for JavaBean information is the JavaBean Specification [Sun, JBS].Model 2:The 0.92 release of the Servlet/JSP Specification described Model 2 as an architecture that uses servlets and JSP pages together in the same application. The term Model 2 disappeared from later releases, but it remains in popular use among Java web developers.Under Model 2, servlets handle the data access and navigational flow, while JSP pages handle the presentation. Model 2 lets Java engineers and HTML developers each work on their own part of the application. A change in one part of a Model 2 application does not mandate a change to another part of the application. HTML developers can often change the look and feel of an application without changing how the back-office servlets work.The Struts framework is based on the Model 2 architecture. It provides a controller servlet to handle the navigational flow and special classes to help with the data access. Awith JSP pages.Summary:In this article, we introduced Struts as an application framework. We examined the technology behind HTTP, the Common Gateway Interface, Java servlets, JSPs, and JavaBeans. We also looked at the Model 2 application architecture to see how it is used to combine servlets and JSPs in the same application.Now that you have had a taste of what it is like to develop a web application with Struts, in chapter 2 we dig deeper into the theory and practice behind the Struts architecture.JSP 应用框架什么是应用框架：框架（framework）是可重用的，半成品的应用程序，可以用来产生专门的定制程序。
Jsp技术介绍外文翻译
附录A中文译文Jsp技术介绍JSP（JA V A SERVER PAGES）是由Sun Microsystems 公司倡导、许多公司参与一起建立的一种动态网页技术标准，其在动态网页的建设中有其强大而特别的功能，他主要用于创建可支持跨平台及跨Web服务器的动态网页。
JSP可与微软的Active Server Pages (ASP)相媲美，但JSP使用的是类似于HTML的标记和Java 代码片段而不是用VBScript。
当你使用不提供ASP本地支持的Web服务器（例如Apache或Netscape服务器）时，你就可以考虑使用JSP了。
Java Server Pages技术可以让web开发人员和设计人员非常容易的创建和维护动态网页，特别是目前的商业系统。
作为JavaTM技术的一部分，JSP能够快速开发出基于web独立平台的应用程序。
JSP 把用户界面从系统内容中分离开来，使得设计人员能够在不改变底层动态内容的前提下改变整个网页布局。
那么什么是Java Server Page呢?简单的说，一个JSP网页就是在HTML网页中包含了能够生成动态内容的可执行应用程序代码。
此应用程序可能包含JavaBeanTM，JDBCTM对象，Enterprise Java BeanTM (E J B )和Remote Method Invocation (RMI)对象，所有的部分都可以非常容易的从JSP网页上访问到。
例如，一个JSP网页可以包含HTML代码所显示的静态文本和图像，也可以调用一个JDBC对象来访问数据库；当网页显示到用户界面上以后，它将包含静态HTML内容和从数据库中找到相应的动态信息。
在JSP网页中，要把用户界面和应用程序分开可以考虑在网页设计人员和开发人员之间执行一个非常方便的授权任务。
它也允许开发人员去建立灵活的代码，从而非常容易的进行更新和重复利用。
由于JSP网页能够根据需要自动进行编译，web设计人员无须重新编译应用程序逻辑就可以改变表述代码。
jsp介绍外文翻译
外文原文JSPJSP (JavaServer Pages) is initiated by Sun Microsystems, Inc., with many companies to participate in the establishment of a dynamic web page technical standards. JSP technology somewhat similar to ASP technology, it is in the traditional HTML web page document (*. htm, *. html) to insert the Java programming paragraph (Scriptlet) and JSP tag (tag), thus JSP documents (*. jsp).Using JSP development of the Web application is cross-platform that can run on Linux, is also available for other operating systems.JSP technology to use the Java programming language prepared by the category of XML tags and scriptlets, to produce dynamic pages package processing logic. Page also visit by tags and scriptlets exist in the services side of the resources of logic. JSP page logic and web page design and display separation, support reusable component-based design, Web-based application development is rapid and easy.Web server in the face of visits JSP page request, the first implementation of the procedures of, and then together with the results of the implementation of JSP documents in HTML code with the return to the customer. Insert the Java programming operation of the database can be re-oriented websites, in order to achieve the establishment of dynamic pages needed to function.JSP and Java Servlet, is in the implementation of the server, usually returned to the client is an HTML text, as long as the client browser will be able to visit.JSP 1.0 specification of the final version is launched in September 1999, December has introduced 1.1 specifications. At present relatively new is JSP1.2 norms, JSP2.0 norms of the draft has also been introduced.JSP pages from HTML code and Java code embedded in one of the components. The server was in the pages of client requests after the Java code and then will generate the HTML pages to return to the client browser. Java Servlet JSP is the technical foundation and large-scale Web application development needs of Java Servlet and JSP support to complete. JSP with the Java technology easy to use, fully object-oriented, and a platform-independent and secure, mainly for all the characteristics of the Internet.JavaScript, which is completely distinct from the Java programming language, is normally used to dynamically generate HTML on the client, building parts of the Webpage as the browser loads the document. This is a useful capability and does not normally overlap with the capabilities of JSP (which runs only on the server). JSP pages still include SCRIPT tags for JavaScript, just as normal HTML pages do. In fact, JSP can even be used to dynamically generate the JavaScript that will be sent to the client. So, JavaScript is not a competing technology; it is a complementary one.It is also possible to use JavaScript on the server, most notably on Sun ONE (formerly iPlanet), IIS, and BroadVision servers. However, Java is more powerful, flexible, reliable, and portable.JSP (a recursive acronym for "JSP: Hypertext Preprocessor") is a free, open-source, HTML-embedded scripting language that is somewhat similar to both ASP and JSP. One advantage of JSP is that the dynamic part is written in Java, which already has an extensive API for networking, database access, distributed objects, and the like, whereas PHP requires learning an entirely new, less widely used language. A second advantage is that JSP is much more widely supported by tool and server vendors than is JSP.Versus Pure Servlets.JSP doesn't provide any capabilities that couldn't, in principle, be accomplished with servlets. In fact, JSP documents are automatically translated into servlets behind the scenes. But it is more convenient to write (and to modify!) regular HTML than to use a zillion println statements to generate the HTML. Plus, by separating the presentation from the content, you can put different people on different tasks: your Web page design experts can build the HTML by using familiar tools and either leave places for your servlet programmers to insert the dynamic content or invoke the dynamic content indirectly by means of XML tags.Does this mean that you can just learn JSP and forget about servlets? Absolutely not! JSP developers need to know servlets for four reasons:a.JSP pages get translated into servlets. You can't understand how JSP works without understanding servlets.b.JSP consists of static HTML, special-purpose JSP tags, and Java code. What kind of Java code? Servlet code! You can't write that code if you don't understand servlet programming.c.Some tasks are better accomplished by servlets than by JSP. JSP is good at generating pages that consist of large sections of fairly well structured HTML or other character data. Servlets are better for generating binary data, building pages withor no output.d.Some tasks are better accomplished by a combination of servlets and JSP than by either servlets or JSP alone.JSP technology strength(1)time to prepare, run everywhere. At this point Java better than PHP, in addition to systems, the code not to make any changes.(2)the multi-platform support. Basically on all platforms of any development environment, in any environment for deployment in any environment in the expansion. Compared ASP / PHP limitations are obvious.(3) a strong scalability. From only a small Jar documents can run Servlet JSP, to the multiple servers clustering and load balancing, to multiple Application for transaction processing, information processing, a server to numerous servers, Java shows a tremendous Vitality.(4)diversification and powerful development tools support. This is similar to the ASP, Java already have many very good development tools, and many can be free, and many of them have been able to run on a variety of platforms under.JSP technology vulnerable:(1)and the same ASP, Java is the advantage of some of its fatal problem. It is precisely because in order to cross-platform functionality, in order to extreme stretching capacity, greatly increasing the complexity of the product.(2)Java's speed is class to complete the permanent memory, so in some cases by the use of memory compared to the number of users is indeed a "minimum cost performance." On the other hand, it also needs disk space to store a series of. Java documents and. Class, as well as the corresponding versions of documents.Know servlets for four reasons:1.JSP pages get translated into servlets. You can't understand how JSP works without understanding servlets.2.JSP consists of static HTML, special-purpose JSP tags, and Java code. What kind of Java code? Servlet code! You can't write that code if you don't understand servlet programming.3.Some tasks are better accomplished by servlets than by JSP. JSP is good at generating pages that consist of large sections of fairly well structured HTML or other character data. Servlets are better for generating binary data, building pages withor no output.4.Some tasks are better accomplished by a combination of servlets and JSP than by either servlets or JSP alone.Versus JavaScriptJavaScript, which is completely distinct from the Java programming language, is normally used to dynamically generate HTML on the client, building parts of the Web page as the browser loads the document. This is a useful capability and does not normally overlap with the capabilities of JSP (which runs only on the server). JSP pages still include SCRIPT tags for JavaScript, just as normal HTML pages do. In fact, JSP can even be used to dynamically generate the JavaScript that will be sent to the client. So, JavaScript is not a competing technology; it is a complementary one.JSP is by no means perfect. Many people have pointed out features that could be improved. This is a good thing, and one of the advantages of JSP is that the specification is controlled by a community that draws from many different companies. So, the technology can incorporate improvements in successive releases.However, some groups have developed alternative Java-based technologies to try to address these deficiencies. This, in our judgment, is a mistake. Using a third-party tool like Apache Struts that augments JSP and servlet technology is a good idea when that tool adds sufficient benefit to compensate for the additional complexity. But using a nonstandard tool that tries to replace JSP is a bad idea. When choosing a technology, you need to weigh many factors: standardization, portability, integration, industry support, and technical features. The arguments for JSP alternatives have focused almost exclusively on the technical features part. But portability, standardization, and integration are also very important. For example, the servlet and JSP specifications define a standard directory structure for Web applications and provide standard files (.war files) for deploying Web applications. All JSP-compatible servers must support these standards. Filters can be set up to apply to any number of servlets or JSP pages, but not to nonstandard resources. The same goes for Web application security settings.JSP six built-in objects:request, response, out, session, application, config, pagecontext, page, exception. ONE.Request for:The object of the package of information submitted by users, by calling the object corresponding way to access the information package, namely the use of the target users can access the information.TWO.Response object:The customer's request dynamic response to the client sent the data.THREE.session object1.What is the session: session object is a built-in objects JSP, it in the first JSP pages loaded automatically create, complete the conversation of management.From a customer to open a browser and connect to the server, to close the browser, leaving the end of this server, known as a conversation. When a customer visits a server, the server may be a few pages link between repeatedly, repeatedly refresh a page, the server should be through some kind of way to know this is the same client, which requires session object.2.session object ID: When a customer's first visit to a server on the JSP pages, JSP engines produce a session object, and assigned a String type of ID number, JSP engine at the same time, the ID number sent to the client, stored in Cookie, this session objects, and customers on the establishment of a one-to-one relationship. When a customer to connect to the server of the other pages, customers no longer allocated to the new session object, until, close your browser, the client-server object to cancel the session, and the conversation, and customer relationship disappeared. When a customer re-open the browser to connect to the server, the server for the customer to create a new session object.FORE.aplication target1.What is the application:Servers have launched after the application object, when a customer to visit the site between the various pages here, this application objects are the same, until the server is down. But with the session difference is that all customers of the application objects are the same, that is, all customers share this built-in application objects.2.application objects commonly used methods:(1)public void setAttribute (String key, Object obj): Object specified parameters will be the object obj added to the application object, and to add the subject of the designation of a keyword index.(2)public Object getAttribute (String key): access to application objects containing keywords for.FIVE.out targetsout as a target output flow, used to client output data. out targets for the output data.SIX.Cookie1.What is Cookie:Cookie is stored in Web server on the user's hard drive section of the text. Cookie allow a Web site on the user's computer to store information on and then get back to it.For example, a Web site may be generated for each visitor a unique ID, and then to Cookie in the form of documents stored in each user's machine.If you use IE browser to visit Web, you will see all stored on your hard drive on the Cookie. They are most often stored in places: c: \ windows \ cookies (in Window2000 is in the C: \ Documents and Settings \ your user name \ Cookies) Cookie is "keyword key = value value" to preserve the format of the record.2.Targets the creation of a Cookie, Cookie object called the constructor can create a Cookie. Cookie object constructor has two string parameters: Cookie Cookie name and value.Cookie c = new Cookie ( "username", "john");3.If the JSP in the package good Cookie object to send to the client, the use of the response addCookie () method.Format: response.addCookie (c)4.Save to read the client's Cookie, the use of the object request getCookies () method will be implemented in all client came to an array of Cookie objects in the form of order, to meet the need to remove the Cookie object, it is necessary to compare an array cycle Each target keywords.外文翻译JSPJSP(JavaServer Pages)是由Sun Microsystems公司倡导、许多公司参与一起建立的一种动态网页技术标准。
外文翻译--JSP及其WEB技术
外文翻译原文及译文学院计算机学院专业计算机科学与技术班级学号姓名指导教师负责教师JSP and WEB technolog1 JSP IntroductionJSP (JavaServer Pages) is a Java-based scripting technology. Is advocated by Sun Microsystems Inc., together with a number of companies involved in the establishment of a dynamic web page technology standards. JSP technology is somewhat similar to ASP technology, It is a traditional HTML page file (*. htm, *. html) to insert Java program segment (Scriptlet) and JSP tag (tag), To form the JSP file（*jsp）. Web development with JSP is a cross-platform applications that can run under Linux, but also in other operating systems. In the JSP of the many advantages, one of which is that it will be HTML encoded Web page from the business logic separated effectively. JSP access with reusable components, such as Servlet, JavaBean and Java-based Web applications. JSP also supports directly in the Web page embedded Java code. JSP can be used two ways to access documents: JSP documents sent by the browser request, the request sent to the Servlet. JSP technology uses Java programming language, XML-type tags and scriptlets, to have a package deal with the logic of dynamic pages. Page tags and scriptlets can also exist in the server access to the resources of the application logic. JSP logic and Web page design and display isolated and support reusable component-based design, Web-based applications more quickly and easily developed.The Web server when meets visits the JSP homepage the request, first carries out segment, will then carry out the result code to return together with JSP in the document HTML for the customer. The insertion Java segment may operate the database, again the directional homepage and so on, realizes the function which the establishment dynamic homepage needs. JSP and Java Servlet are the same, is in the server end execution, usually returns to this client side is a HTML text, therefore client side, so long as has the browser to be able to glance over.The JSP page is composed of the HTML code and the inserting Java code. The server in the page by the client side was requested that later will carry on processing to these Java code, will then produce the HTML page will return gives the client side the browser. Java Servlet is the JSP technology base, moreover the large-scale Web applicationprocedure's development needs Java Servlet and the JSP coordination can complete. JSP had the Java technology simply easy to use, complete object-oriented, had the platform independency, and safe reliable, mainly faced Internet's all characteristics.2 JSP computing techniqueTo carry on the dynamic website conveniently fast the development, JSP has made the improvement in the following several aspects, causes it to become builds the cross platform fast the dynamic website first choice plan.2.1 carries on the content production and the demonstration separatesWith the JSP technology, the Web page development personnel may use HTML or the XML marking design and the formatted final page, and uses the JSP marking or the tootsy produces on page's dynamic content originally. Production content's logic is sealed in marks and in the JavaBeans module, and ties up in the script, all scripts in server end movement. Because core logic is sealed in marks and in JavaBeans, therefore the Web administrative personnels and the page designer, can edit and use the JSP page, but does not affect the content the production. In the server end, the JSP engine explained that the JSP marking and the script, produce the content which requested, and (or XML) page's form transmits the result by HTML the browser. This both are helpful in the author protects own code, and can guarantee any based on the HTML Web browser's complete usability.2.2 may entrust with heavy responsibility the moduleThe overwhelming majority JSP page relies on may entrust with heavy responsibility, the cross platform module (JavaBeans or Enterprise the JavaBeans module) carries out complex processing which the application procedure requests. The development personnel can share and exchange the execution ordinary operation the module, or causes these modules uses for more users and the customer association. Has accelerated the overall development process based on module's method, and causes each kind of organization obtains balanced in their existing skill and in the optimized result development endeavor.2.3 uses markingThe Web page development personnel will not be the familiar script language programmers. The JSP technology has sealed many functions, these functions are easy touse, marking to carry on the dynamic content production with JSP in the related XML to need. The standard JSP marking can visit and the instantiation JavaBeans module, the establishment or the retrieval module attribute, downloads Applet, as well as the execution difficulty with codes and the time-consuming function with other methods.2.4 adapts the platformNearly all platforms support Java, JSP+JavaBeans to be possible to pass unimpeded nearly under all platforms. Transplants from a platform to other platform, JSP and JavaBeans does not even need to translate, because the Java byte code is standard has nothing to do with the platform.2.5 database connectionIn Java connects the database the technology is the JDBC, Java procedure is connected through the JDBC driver and the database, operations and so on execution inquiry, extraction data. Sun Corporation has also developed JDBC-ODBC bridge, uses this technical Java procedure to be possible to visit has the ODBC driver database, at present the majority database systems have the ODBC driver, therefore the Java procedure can visit such as Oracle, Sybase, MS SQL Server and databases and so on MS Access. In addition, through the development marking storehouse, the JSP technology may further expand. The third party development personnel and other personnel may found their marking storehouse for the commonly used function. This enables the Web page development personnel to be able to use the familiar tool and to be similar to marking same carries out the specific function component to carry on the work. The JSP technology very easy conformity to many kinds of application architecture, to use the extant tool and the skill, and can expand to the support enterprise distributional application.3 Eclipse function synopsisMore and more Java development personnel already started the productivity which and the quality income appreciates Eclipse JDT to provide. It was the Java editor provides grammar Gao Liang to demonstrate that the formatting, the fold, the content were auxiliary, code template and so on many functions. It grows unceasingly available restructuring and the code generation function set permits you in a higher rank the operation code, and automated usual code intensity duty and easy wrong duty. Moreover, in develops the codeand uses JDT to compile and to carry out the JUnit test built-in support carries on the unit testing after the code, may use Eclipse the first-class Java debugger debugging when the movement meets any question. Besides JDT, Eclipse SDK- the most popular downloading - also contains Plug-in Development Environment(PDE). PDE used the specific function to expand JDT to construct the Eclipse plug-in unit - based on the Eclipse application procedure basic construction agglomeration. In fact, uses the tool which provides by Eclipse itself to be able to surmount the Java development, may expand the existing Eclipse application procedure, or even founds the brand-new application procedure.Eclipse by a script level constitution, contains in many functional modules or the Eclipse terminology so-called “the plug-in unit”. The plug-in unit is provides all functions in the Eclipse application procedure the module. They cooperate through its API to pay the final outcome together. In Eclipse, even the most foundation's function, for instance the search and the start installment's plug-in unit, seals in the plug-in unit. In order to expand the existing Eclipse function or carry on the construction in above, the plug-in unit the concrete expansion contribution for the expansion spot which will expose by other plug-in units. Usually, the plug-in unit concentrates the specific region responsibility, and gives through or a many expansion way other responsibility designation other plug-in units. For example, a plug-in unit allows you parallel to compare two documents visibly the contents, but it will not care how to read these documents even how to explain these document structure; This is other plug-in unit's work. When compared with two documents, this plug-in unit first inspects whether to have another plug-in unit to be possible to explain these document structure. If found one, it to the plug-in unit inquiry related file organization information which found, and used this information in the comparison process.May see that the modular construction was Eclipse has provided the huge flexibility, and provided one to be possible to support the massive application procedure platform which the original design has not expected.4 Structs function synopsisStruts is a MVC frame (Framework), uses in developing Java fast the Web application. Struts realizes the key point in C(Controller), Action which and we have custom-madeincluding ActionServlet/RequestProcessor, was also V(View) provides a series of rows to have custom-made the label (Custom Tag). Spring is a light vessel (light-weight container), its core is the Bean factory (Bean Factory), with constructs M(Model) which we need. Above this foundation, Spring has provided AOP (Aspect-Oriented Programming, face stratification plane programming) realization, provides under the non-management environment with it to declare services and so on way business, security; Is more convenient to Bean factory expansion ApplicationContext we to realize the J2EE application; DAO/ORM realizes facilitates us to carry on the database the development; Web MVC and Spring Web have provided Java the Web application frame or carries on the integration with other popular Web frame. That is may a both use, achieve both own characteristic carries on supplementary.Structs is the kind which, servlet and the JSP mark a group cooperates mutually, they compose the MVC 2 designs which may entrust with heavy responsibility. This definition expressed that Struts is a frame, but is not a storehouse, but Struts has also contained the rich mark storehouse and the independence in this frame work utility program class.Client browser (customer browser), the request founds an event from customer browser's each HTTP. The Web vessel will use a HTTP response to make the response.Controller (controller), the controller receive from browser's request, and decided that sends out where this request. Speaking of Struts, the controller is an order design pattern which realizes by servlet. struts-config.xml document disposition controller.Service logic, the service logic renewal model's condition, and helps the control application procedure the flow. Speaking of Struts, this is through takes the actual service logic “thin” the packing Action kind to complete.Model (model) condition, model expression application procedure condition. Service object renewal application procedure condition. ActionForm bean in conversation level or request level expression model condition, but is not in the lasting level. The JSP document uses JSP to mark the read from the ActionForm bean information.View (view), the view is a JSP document. And does not have the flow logic, does not have the service logic, also does not have the model information -- Only then marks. The mark causes Struts is different with other frames (for example Velocity) one of factors.Just like the Struts controller is (event usually is HTTP post) maps the event kind of servlet. you to expect - the air-operated controller use configuration files to cause you notto need to carry on to these values the hard code. The time has changed, but method as before.The Action kind, ActionForm maintains the Web application procedure the conversation condition. ActionForm is one abstract class, must found this kind of subclass for each input form model. When I said when input form model, what refers to the ActionForm expression is establishes or in the renewal general sense data by the HTML form.The Action kind is service logic packing. A Action kind of use is transforms HttpServletRequest into the service logic. Must use Action, please found its subclass and covers process () the method.ActionServlet (Command) will use perform () the method the parametrization kind to transmit for ActionForm. Still did not have too many repugnant request.getParameter () to transfer. When the event progresses to this step, the input form data (or HTML form data) has been withdrawn from the request class and shifts to the ActionForm kind.Considered that a Action kind of another way is the Adapter design pattern. The Action use will be “a kind of connection will transform another connection which will need for the client. Adapter enables the kind the joint operation, if does not have Adapter, then these kinds will be unable because of the incompatible connection the joint operation.”. In this example's client is ActionServlet, it knows nothing about to our concrete service class connection. Therefore, Struts has provided a service connection which it can understand, namely Action. Through expands Action, we cause our service connection and the Struts service connection maintain compatible.5 CSS synopsisThe CSS edition method is the same with HTML, may also be any text editor or the homepage edition software, but also has uses for to edit CSS specially the software. If you write the CSS sentence regards the exterior cascading style sheet, but transfers in the HTML document, then its extension saves .css to be possible. Initially the technical personnel found out HTML, mainly stresses on the definition content, for instance expressed that a paragraph, indicates the title, but excessively has not designed HTML the typesetting and the contact surface effect.Along with the Internet rapid development, HTML is widely applied, the surfer people hoped certainly that the homepage makes attractive, therefore the HTMLtypesetting and the contact surface effect's limitation exposes day by day. In order to solve this problem, the people also took many tortuous paths, has used some not good method, for instance increases many attribute results to HTML becomes the code very extremely fat, turns the picture the text, excessively many comes the typesetting using Table, expresses the white space with the blank picture and so on. Appears until CSS.CSS may be a homepage design breakthrough, it has solved the homepage contact surface typesetting difficult problem. May such say that HTML Tag is mainly defines the homepage content (Content), but CSS decided how these homepage content does demonstrate (Layout). The CSS English is Cascading Style Sheets, Chinese may translate the tandem cascading style sheet. CSS may divide into three kinds according to its position: In inlays the style (Inline Style), internal cascading style sheet (Internal Style Sheet), exterior cascading style sheet (External Style Sheet).6 HTML function synopsisHyper Text Markup the Language hypertext mark language is one kind uses for to manufacture the hypertext documents the simple mark language. The hypertext documents which compiles with HTML are called the HTML documents, it can the independence in each kind of operating system platform (for example UNIX, WINDOWS and so on). HTML has served as since 1990 on World Wide Web the information to express the language, uses in describing the Homepage form design and it and on WWW the other Homepage linked information.The HTML documents (i.e. the Homepage source document) was one has laid aside the mark ASCII text document, usually it had .html or the .htm document extension. Produces HTML documents mainly to have the following three ways: 1. the manual direct compilation (e.g. ASCII text editor which or other HTML edition tool likes with you). 2. will have other form documents through certain format conversion tool (for example the WORD documents) to transform the HTML documents. 3. by the Web server (or said that the HTTP server) one only then real-time dynamic produces. the HTML language is through uses each kind of mark (tags) to mark the documents the structure as well as marks the ultra chain (Hyperlink) the information.Although the HTML language described the documents structure form, but how can't define the documents information to precisely demonstrate and arrange, but is onlysuggested how the Web browser (for example Mosiac, Netscape and so on) should demonstrate and arrange these information, is decided finally in front of user's demonstration result by the Web browser's demonstration style and to the mark explanatory ability. Why is the identical documents the effect which demonstrated in the different browser meets is dissimilar. At present the HTML language's edition is 2.0, it is based on SGML (Standard Generalized Markup Language, standard sets at sign language generally, as soon as is applies mechanically describes digitized documents structure and manages its content complex standard) a subset to evolve comes. Although in next edition's standard HTML3.0 (is also called HTML+) to draw up, but some the partial experimental nature draft standard widely has been used, the mostly outstanding Web browser (for example Netscape and so on) can explain in the HTML3.0 part new mark, therefore introduced in this chapter some HTML3.0 new mark has been accepted by the most browsers.7 Js script language synopsisJS is javascrip, Javascript is one kind the script language which comes by the Netscape LiveScript development, the main purpose is to solve the server terminal language, for instance Perl, carry-over speed question. At that time served the end to need to carry on the confirmation to the data, because the network speed was quite slow, only then 28.8kbps, the confirmation step waste's time were too many. Therefore Netscape browser Navigator has joined Javascript, has provided the data confirmation basic function.The JavaScript official name is “ECMAScript”. This standard by ECMA organization development and maintenance. ECMA-262 is the official JavaScript standard. This standard based on JavaScript (Netscape) and JScript (Microsoft). Netscape (Navigator 2.0) Brendan Eich has invented this language, started from 1996, already appeared in all Netscape and in the Microsoft browser. The ECMA-262 development began in 1996, in 1997 July, the ECMA general meeting has accepted its first edition.Script script uses one specific descriptive language, rests on certain form compilation to be possible the execution document, is also called as great or the batch run document. The script usually may transfer temporarily by the application procedure and carry out. Each kind of script present widely is applied in the homepage design, because the script not only may reduce the homepage the scale and raises the homepage browsing speed,moreover may enrich the homepage performance, like animation, sound and so on. Cites a most common example, when we click in the homepage the E-mail address can transfer Outlook Express or the Foxmail this kind of mail software automatically, is realizes through the script function. Also because of script these characteristics, the human who harbors ulterior motives by some are often using. For example joins some destruction computer system's order in the script, like this works as the user browsing homepage, once transfers this kind of script, will then cause the user the system to come under the attack. Therefore the user should act according to visits homepage the trust degree selective security rank, specially regarding these itself content on the illegal homepage, do not permit the use script easily. Through “the safe establishment” the dialog box, the choice “the script” under option each kind of establishment may with ease realize to script being forbid and begins using.Present's script language is quite many, script language execution generally only with concrete explanation actuator related, so long as therefore on the system has the corresponding language interpreter to be possible to achieve the cross platform. Script (Script), is includes order and so on bind and alias sets, you may save this set are an independent document then in the time which needs carries out, like this may facilitate you in the CS use. The script may save for the suffix named .cfg document places under the cstrike folder, when execution in control bench input: exec (script filename) .cfg then. For instance saves a script is the buys.cfg document, inputs in the control bench: execbuys.cfg may realize the function which we need. Must realize an order, so long as is good this process definition (alias), and assigns a key position for this order, so long as later according to will assign the good key position, may realize this proceJSP及其WEB技术. 1 JSP简介JSP（JavaServer Pages）是一种基于Java的脚本技术。
JSP技术简介及特点(外文文献译文)
JSP Technology Conspectus and SpecialtiesThe JSP (Java Server Pages) technology is used by the Sun micro-system issued by the company to develop dynamic Web application technology. With its easy, cross-platform, in many dynamic Web application programming languages, in a short spa n of a few years, has formed a complete set of standards, and widely used in electr onic commerce, etc. In China, the JSP now also got more extensive attention; get a good development, more and more dynamic website to JSP technology. The related technologies of JSP are briefly introduced.The JSP a simple technology can quickly and with the method of generating W eb pages. Use the JSP technology Web page can be easily display dynamic content. The JSP technology are designed to make the construction based on Web applicati ons easier and efficient, and these applications and various Web server, application server, the browser and development tools work together.The JSP technology isn't the only dynamic web technology, also not the first o ne, in the JSP technology existed before the emergence of several excellent dynami c web technologies, such as CGI, ASP, etc. With the introduction of these technolo gies under dynamic web technology, the development and the JSP. Technical JSP the development background and development historyIn web brief history, from a world wide web that most of the network informati on static on stock transactions evolution to acquisition of an operation and infrastru cture. In a variety of applications, may be used for based on Web client, look no res trictions.Based on the browser client applications than traditional based on client/server applications has several advantages. These benefits include almost no limit client a ccess and extremely simplified application deployment and management (to update an application, management personnel only need to change the program on a serve r, not thousands of installation in client applications). So, the software industry is r apidly to build on the client browser multilayer application.The rapid growth of exquisite based Web application requirements developme nt of technical improvements. Static HTML to show relatively static content is righ t choice, the new challenge is to create the interaction based on Web applications, i n these procedures, the content of a Web page is based on the user's request or the state of the system, and are not predefined characters.For the problem of an early solution is to use a CGI - BIN interface. Developer s write to interface with the relevant procedures and separate based on Web applica tions, the latter through the Web server to invoke the former. This plan has serious problem -- each new extensible CGI requirements in a new process on the server. I f multiple concurrent users access to this procedure, these processes will use the W eb server of all available resources, and the performance of the system will be redu ced to extremely low.Some Web server providers have to provide for their server by plugins "and" th e API to simplify the Web application development. These solutions are associated with certain Web server, cannot solve the span multiple suppliers solutions. For exa mple, Microsoft's Active Server mix (ASP) technology in the Web page to create d ynamic content more easily, but also can work in Microsoft on Personal Web Serve r and IIS.There are other solutions, but cannot make an ordinary page designers can easi ly master. For example, such as the Servlet Java technologies can use Java languag e interaction application server code easier. Developers to write such Servlet to rec eive signals from the Web browser to generate an HTTP request, a dynamic respon se (may be inquires the database to finish the request), then send contain HTML or XML documents to the response of the browser.Note: one is based on a Java Servlet Java technical operation in the server pro gram (with different, the latter operating in the Applet browser end). In this book th e Servlet chapter .Using this method, the entire page must have made in Java Servlet. If develope rs or Web managers want to adjust page, you'll have to edit and recompile the Servl et Java, even in logic has been able to run. Using this method, the dynamic content with the application of the page still need to develop skills.Obviously, what is needed is a industry to create dynamic content within the sc ope of the pages of the solution. This program will solve the current scheme are li mited. As follows:can on any Web server or applications. will application page displays and separation. can rapidly developing and testing.simplify the interactive development based on Web application process. TheJSP technology is designed to meet such requirements. The JSP specification is a Web server, application server, trading system and develops extensive cooperation between the tool suppliers. From this standard to develop the existing integration a nd balance of Java programming environment (for example, Java Servlet and Java Beans) support techniques and tools. The result is a kind of new and developing m ethod based on Web applications, using component-based application logic page de signers with powerful functions.Overall Semantics of a JSP PageA JSP page implementation class defines a JSP Service () method mapping fro m the request to the response object. Some details of this transformation are specifi c to the scripting language used (see Chapter JSP.9, “Scripting”). Most details are n ot language specific and are described in this chapter.The content of a JSP page is devoted largely to describing the data that is writt en into the output stream of the response. (The JSP container usually sends this dat a back to the client.) The description is based on a JSP Writer object that is expose d through the implicit object out (see Section JSP.1.8.3, “Implicit Objects”). Its val ue varies:Initially, out is a new JSP Writer object. This object may be different from the stream object returned from response, get Writer (), and may be considered to be in terposed on the latter in order to implement buffering (see Section JSP.1.10.1, “The page Directive”). This is the initial out object. JSP page authors are prohibited fro m writing directly to either the Print Writer or Output Stream associated with the S ervlet Response.The JSP container should not invoke response.get Writer () until the time when the first portion of the content is to be sent to the client. This enables a number of uses of JSP, including using JSP as a language to “glue” actions that deliver binary content, or reliably forwarding to a Servlet, or change dynamically the content type of the response before generating content. See Chapter JSP.4, “Internationalization Issues”.Within the body of some actions, out may be temporarily re-assigned to a diffe rent (nested) instance of a JSP Writer object. Whether this is the case depends on th e details of the action’s semantics. Typically the content of these temporary streams is appended to the stream previously referred to by out, and out is subsequently re-assigned to refer to the previous (nesting) stream. Such nested streams are always b uffered, and require explicit flushing to a nesting stream or their contents will be di scarded.If the initial out JSP Writer object is buffered, then depending upon the value o f the auto-Flush attribute of the page directive, the content of that buffer will either be automatically flushed out to the Servlet Response output stream to obviate overf low, or an exception shall be thrown to signal buffer overflow. If the initial out JSP Writer is unbuffered, then content written to it will be passed directly through to th e Servlet Response output stream.A JSP page can also describe what should happen when some specific events o ccur. In JSP 2.1, the only events that can be described are the initialization and the destruction of the page. These events are described using “well-known method na mes” in declaration elements..JavaScript is used for the first kind is browser, the dynamic general purpose of client scripting language. Netscape first proposed in 1995, but its JavaScript Live S cript called. Then quickly Netscape Live Script renamed JavaScript, Java develope rs with them from the same issued a statement. A statement Java and JavaScript wil l complement each other, but they are different, so the technology of the many dis missed the misunderstanding of the two technologies.JavaScript to create user interface control provides a scripting language. In fact , in the browser into the JavaScript code logic. It can support such effect: when the cursor on the Web page of a mobile user input validation or transform image.Microsoft also writes out their JavaScript version and the JSP script called. Mi crosoft and Netscape support JavaScript and JSP script around core characteristics and European Manufacturers is made by (ECMA) standards organization, the contr ol standard of scripting language. ECMA its scripting language ECMAScript name d.Servlets and JSP often include fragments of information that are common to an organization, such as logos, copyrights, trademarks, or navigation bars. The web a pplication uses the include mechanisms to import the information wherever it is ne eded, since it is easier to change content in one place then to maintain it in every pi ece of code where it is used. Some of this information is static and either never or r arely changes, such as an organization's logo. In other cases, the information is more dynamic and changes often and unpredictably, such as a textual greeting that mus t be localized for each user. In both cases, you want to ensure that the servlet or JS P can evolve independently of its included content, and that the implementation of the servlet or JSP properly updates its included content as necessary.You want to include a resource that does not change very much (such as a page fragment that represents a header or footer) in a JSP. Use the include directive in t he including JSP page, and give the included JSP segment a JSP extension.You want to include content in a JSP each time it receives a request, rather tha n when the JSP is converted to a servlet. Use the JSP: include standard action.You want to include a file dynamically in a JSP, based on a value derived from a configuration file. Use the JSP: include standard action. Provide the value in an external properties file or as a configuration parameter in the deployment descripto r.You want to include a fragment of an XML file inside of a JSP document, or in clude a JSP page in XML syntax. Use the JSP: include standard action for the inclu des that you want to occur with each request of the JSP. Use the JSP: directive.incl ude element if the includes action should occur during the translation phase.You want to include a JSP segment from outside the including file's context. U se the c: importThe operation principle and the advantages of JSP tagsIn this section of the operating principle of simple introduction JSP and strengt hs.For the first time in a JSP documents requested by the engine, JSP Servlet is tr ansformed into a document JSP. This engine is itself a Servlet. The operating proce ss of the JSP shown below:(1) The JSP engine put the JSP files converting a Java source files (Servlet), if you find the files have any grammar mistake JSP, conversion process will interrupt, and to the server and client output error messages.(2) If converted, with the engine JSP Java source file compiler into a correspon ding scale-up files.(3) To create a Servlet (JSP page), the transformation of the Servlet JSP Init () method was executed, JSP Init () method in the life cycle of Servlet executed only once.(4) JSP Service () method invocation to the client requests. For each request, J SP engine to create a new thread for processing the request. If you have multiple cl ients and request the JSP files, JSP engine will create multiple threads. Each client requests a thread. To execute multi-thread can greatly reduce the requirement of sy stem resources, improving the concurrency value and response time. But also shoul d notice the multi-thread programming, due to the limited Servlet always in respon se to memory, so is very fast.(5) If the file has been modified. The JSP, server will be set according to the do cument to decide whether to recompile, if need to recompile, will replace the Servl et compile the memory and continue the process.(6) Although the JSP efficiency is high, but at first when the need to convert and compile and some slight delay. In addition, if at any time due to reasons of syste m resources, JSP engine will in some way of uncertain Servlet will remove from m emory. When this happens JSP Destroy () method was first call.(7) And then Servlet examples were marked with "add" garbage collection. Bu t in JSP Init () some initialization work, if establish connection with database, or to establish a network connection, from a configuration file take some parameters, su ch as, in JSP Destroy () release of the corresponding resources.Based on a Java language has many other techniques JSP page dynamiccharacteristics, technical have embodied in the following aspects:One. Simplicity and effectivenessThe JSP dynamic web pages with the compilation of the static HTML pages of writing are very similar. Just in the original HTML page add JSP tags, or some of t he proprietary scripting (this is not necessary). So, a familiar with HTML page writ e design personnel may be easily performed JSP page development. And the devel opers can not only, and write script by JSP tags used exclusively others have writte n parts to realize dynamic pages. So, an unfamiliar with the web developers scripti ng language, can use the JSP make beautiful dynamic pages. And this in other dyna mic web development is impossible.Tow. The independence of the programThe JSP are part of the family of the API Java, it has the general characteristics of the cross-platform Java program. In other words, is to have the procedure, name ly the independence of the platform, 6 Write bid anywhere!Three. Procedures compatibilityThe dynamic content can various JSP form, so it can show for all kinds of cust omers, namely from using HTML/DHTML browser to use various handheld wirele ss equipment WML (for example, mobile phones and PDA), personal digital equip ment to use XML applications, all can use B2B JSP dynamic pages.Four. Program reusabilityIn the JSP page can not directly, but embedded scripting dynamic interaction w ill be cited as a component part. So, once such a component to write, it can be repe ated several procedures, the program of the reusability. Now, a lot of standard Java Beans library is a good example.JSP technology strengthTime to prepare, run everywhere. At this point Java better than PHP, in additio n to systems, the code not to make any changes.(2) The multi-platform support. Basically on all platforms of any development environment, in any environment for deployment in any environment in the expans ion. Compared ASP / PHP limitations are obvious.(3) A strong scalability. From only a small Jar documents can run Servlet JSP, t o the multiple servers clustering and load balancing, to multiple Application for tra nsaction processing, information processing, a server to numerous servers, Java sh ows a tremendous Vitality.(4) Diversification and powerful development tools support. This is similar to t he ASP, Java already has many very good development tools, and many can be free , and many of them have been able to run on a variety of platforms under.JSP technology vulnerable:(1) And the same ASP, Java is the advantage of some of its fatal problem. It is precisely because in order to cross-platform functionality, in order to extreme stretc hing capacity, greatly increasing the complexity of the product.(2) Java's speed is class to complete the permanent memory, so in some cases by the use of memory compared to the number of users is indeed a "minimum cost performance.”On the other hand, it also needs disk space to store a series of. Java d ocuments and. Class, as well as the corresponding versions of documents.Know servlets for four reasons:1. JSP pages get translated into servlets. You can't understand how JSP workswithout understanding servlets.2. JSP consists of static HTML, special-purpose JSP tags, and Java code. What kind of Java code? Servlet code! You can't write that code if you don't understand servlet programming.3. Some tasks are better accomplished by servlets than by JSP. JSP is good at g enerating pages that consist of large sections of fairly well structured HTML or oth er character data. Servlets are better for generating binary data, building pages with highly variable structure, and performing tasks (such as redirection) that involve li ttle or no output.4. Some tasks are better accomplished by a combination of servlets and JSP th an by either servlets or JSP alone.Versus JavaScriptJavaScript, which is completely distinct from the Java programming language, is normally used to dynamically generate HTML on the client, building parts of the Web page as the browser loads the document. This is a useful capability and does not normally overlap with the capabilities of JSP (which runs only on the server). J SP pages still include SCRIPT tags for JavaScript, just as normal HTML pages do. In fact, JSP can even be used to dynamically generate the JavaScript that will be se nt to the client. So, JavaScript is not a competing technology; it is a complementar y one.JSP is by no means perfect. Many people have pointed out features that could be improved. This is a good thing, and one of the advantages of JSP is that the spec ification is controlled by a community that draws from many different companies. So, the technology can incorporate improvements in successive releases.However, some groups have developed alternative Java-based technologies to t ry to address these deficiencies. This, in our judgment, is a mistake. Using a third-p arty tool like Apache Struts that augments JSP and servlet technology is a good ide a when that tool adds sufficient benefit to compensate for the additional complexity . But using a nonstandard tool that tries to replace JSP is a bad idea. When choosin g a technology, you need to weigh many factors: standardization, portability, integr ation, industry support, and technical features. The arguments for JSP alternatives have focused almost exclusively on the technical features part. But portability, stan dardization, and integration are also very important. For example, the servlet and JSP specifications define a standard directory structure for Web applications and pro vide standard files (.war files) for deploying Web applications. All JSP-compatible servers must support these standards. Filters can be set up to apply to any number o f servlets or JSP pages, but not to nonstandard resources. The same goes for Web a pplication security settings.JSP技术简介及特点JSP（Java Server Pages）技术是由Sun公司发布的用于开发动态Web应用的一项技术。
Servlet和JSP技术简介中英文对照外文翻译文献
(文档含英文原文和中文翻译)中英文资料外文翻译An Overview of Servlet and JSP Technology 1.1A Servlet's JobServlets are Java programs that run on Web or application servers, acting as a middle layer between requests coming from Web browsers or other HTTP clients and databases or applications on the HTTP server. Their job is to perform the following tasks, as illustrated in Figure 1-1.Figure 1-11．Read the explicit data sent by the client.The end user normally enters this data in an HTML form on a Web page. However, the data could also come from an applet or a custom HTTP client program.2．Read the implicit HTTP request data sent by the browser.Figure 1-1 shows a single arrow going from the client to the Web server (the layer where servlets and JSP execute), but there are really two varieties of data: the explicit data that the end user enters in a form and the behind-the-scenes HTTP information. Both varieties are critical. The HTTP information includes cookies, information about media types and compression schemes the browser understands, and so on.3．Generate the results.This process may require talking to a database, executing an RMI or EJB call, invoking a Web service, or computing the response directly. Your real data may be in a relational database. Fine. But your database probably doesn't speak HTTP or return results in HTML, so the Web browser can't talk directly to the database. Even if it could, for security reasons, you probably would not want it to. The same argument applies to most other applications. You need the Web middle layer to extract the results inside a document.4．Send the explicit data (i.e., the document) to the client.This document can be sent in a variety of formats, including text (HTML or XML), binary (GIF images), or even a compressed format like gzip that is layered on top of some other underlying format. But, HTML is by far the most common format, so an important servlet/JSP task is to wrap the results inside of HTML.5．Send the implicit HTTP response data.Figure 1-1 shows a single arrow going from the Web middle layer (the servlet or JSP page) to the client. But, there are really two varieties of data sent: the document itself and the behind-the-scenes HTTP information. Again, both varieties are critical to effective development. Sending HTTP response data involves telling the browser or other client what type of document is being returned (e.g., HTML), setting cookies and caching parameters, and other such tasks.1.2Why Build Web Pages Dynamically?Many client requests can be satisfied by prebuilt documents, and the server would handle these requests without invoking servlets. In many cases, however, a static result is not sufficient, and a page needs to be generated for each request. There are a number of reasons why Web pages need to be built on-the-fly:1．The Web page is based on data sent by the client.For instance, the results page from search engines and order-confirmation pages at online stores are specific to particular user requests. You don't know what to display until you read the data that the user submits. Just remember that the user submits two kinds of data: explicit (i.e., HTML form data) and implicit (i.e., HTTP request headers). Either kind of input can be used to build the output page. In particular, it is quite common to build a user-specific page based on a cookie value.2．The Web page is derived from data that changes frequently.If the page changes for every request, then you certainly need to build the response at request time. If it changes only periodically, however, you could do it two ways: you could periodically build a new Web page on the server (independently of client requests), or you could wait and only build the page when the user requests it. The right approach depends on the situation, but sometimes it is more convenient to do the latter: wait for the user request. For example, a weather report or news headlines site might build the pages dynamically, perhaps returning a previously built page if that page is still up to date.3．The Web page uses information from corporate databases or other server-side sources.If the information is in a database, you need server-side processing even if the client is using dynamic Web content such as an applet. Imagine using an applet by itself for a search engine site:"Downloading 50 terabyte applet, please wait!" Obviously, that is silly; you need to talk to the database. Going from the client to the Web tier to the database (a three-tier approach) instead of from an applet directly to a database (a two-tier approach) provides increased flexibility and security with little or no performance penalty. After all, the database call is usually the rate-limiting step, so going through the Web server does not slow things down. In fact, a three-tier approach is often faster because the middle tier can perform caching and connection pooling.In principle, servlets are not restricted to Web or application servers that handle HTTP requests but can be used for other types of servers as well. For example, servlets could be embedded in FTP or mail servers to extend their functionality. And, a servlet API for SIP (Session Initiation Protocol) servers was recently standardized (see /en/jsr/detail?id=116). In practice, however, this use of servlets has not caught on, and we'll only be discussing HTTP servlets.1.3The Advantages of Servlets Over "Traditional" CGIJava servlets are more efficient, easier to use, more powerful, more portable, safer, and cheaper than traditional CGI and many alternative CGI-like technologies.1．EfficientWith traditional CGI, a new process is started for each HTTP request. If the CGI program itself is relatively short, the overhead of starting the process can dominate the execution time. With servlets, the Java virtual machine stays running and handles each request with a lightweight Java thread, not a heavyweight operating system process. Similarly, in traditional CGI, if there are N requests to the same CGI program, the code for the CGI program is loaded into memory N times. With servlets, however,there would be N threads, but only a single copy of the servlet class would be loaded. This approach reduces server memory requirements and saves time by instantiating fewer objects. Finally, when a CGI program finishes handling a request, the program terminates. This approach makes it difficult to cache computations, keep database connections open, and perform other optimizations that rely on persistent data. Servlets, however, remain in memory even after they complete a response, so it is straightforward to store arbitrarily complex data between client requests.2．ConvenientServlets have an extensive infrastructure for automatically parsing and decoding HTML form data, reading and setting HTTP headers, handling cookies, tracking sessions, and many other such high-level utilities. In CGI, you have to do much of this yourself. Besides, if you already know the Java programming language, why learn Perl too? You're already convinced that Java technology makes for more reliable and reusable code than does Visual Basic, VBScript, or C++. Why go back to those languages for server-side programming?3．PowerfulServlets support several capabilities that are difficult or impossible to accomplish with regular CGI. Servlets can talk directly to the Web server, whereas regular CGI programs cannot, at least not without using a server-specific API. Communicating with the Web server makes it easier to translate relative URLs into concrete path names, for instance. Multiple servlets can also share data, making it easy to implement database connection pooling and similar resource-sharing optimizations. Servlets can also maintain information from request to request, simplifying techniques like session tracking and caching of previous computations.4．PortableServlets are written in the Java programming language and follow a standard API. Servlets are supported directly or by a plugin on virtually every major Web server. Consequently, servlets written for, say, Macromedia JRun can run virtually unchangedon Apache Tomcat, Microsoft Internet Information Server (with a separate plugin), IBM WebSphere, iPlanet Enterprise Server, Oracle9i AS, or StarNine WebStar. They are part of the Java 2 Platform, Enterprise Edition (J2EE; see /j2ee/), so industry support for servlets is becoming even more pervasive.5．InexpensiveA number of free or very inexpensive Web servers are good for development use or deployment of low- or medium-volume Web sites. Thus, with servlets and JSP you can start with a free or inexpensive server and migrate to more expensive servers with high-performance capabilities or advanced administration utilities only after your project meets initial success. This is in contrast to many of the other CGI alternatives, which require a significant initial investment for the purchase of a proprietary package.Price and portability are somewhat connected. For example, Marty tries to keep track of the countries of readers that send him questions by email. India was near the top of the list, probably #2 behind the U.S. Marty also taught one of his JSP and servlet training courses (see /) in Manila, and there was great interest in servlet and JSP technology there.Now, why are India and the Philippines both so interested? We surmise that the answer is twofold. First, both countries have large pools of well-educated software developers. Second, both countries have (or had, at that time) highly unfavorable currency exchange rates against the U.S. dollar. So, buying a special-purpose Web server from a U.S. company consumed a large part of early project funds.But, with servlets and JSP, they could start with a free server: Apache Tomcat (either standalone, embedded in the regular Apache Web server, or embedded in Microsoft IIS). Once the project starts to become successful, they could move to a server like Caucho Resin that had higher performance and easier administration but that is not free. But none of their servlets or JSP pages have to be rewritten. If theirproject becomes even larger, they might want to move to a distributed (clustered) environment. No problem: they could move to Macromedia JRun Professional, which supports distributed applications (Web farms). Again, none of their servlets or JSP pages have to be rewritten. If the project becomes quite large and complex, they might want to use Enterprise JavaBeans (EJB) to encapsulate their business logic. So, they might switch to BEA WebLogic or Oracle9i AS. Again, none of their servlets or JSP pages have to be rewritten. Finally, if their project becomes even bigger, they might move it off of their Linux box and onto an IBM mainframe running IBM WebSphere. But once again, none of their servlets or JSP pages have to be rewritten.6．SecureOne of the main sources of vulnerabilities in traditional CGI stems from the fact that the programs are often executed by general-purpose operating system shells. So, the CGI programmer must be careful to filter out characters such as backquotes and semicolons that are treated specially by the shell. Implementing this precaution is harder than one might think, and weaknesses stemming from this problem are constantly being uncovered in widely used CGI libraries.A second source of problems is the fact that some CGI programs are processed by languages that do not automatically check array or string bounds. For example, in C and C++ it is perfectly legal to allocate a 100-element array and then write into the 999th "element," which is really some random part of program memory. So, programmers who forget to perform this check open up their system to deliberate or accidental buffer overflow attacks.Servlets suffer from neither of these problems. Even if a servlet executes a system call (e.g., with Runtime.exec or JNI) to invoke a program on the local operating system, it does not use a shell to do so. And, of course, array bounds checking and other memory protection features are a central part of the Java programming language.7．MainstreamThere are a lot of good technologies out there. But if vendors don't support them and developers don't know how to use them, what good are they? Servlet and JSP technology is supported by servers from Apache, Oracle, IBM, Sybase, BEA, Macromedia, Caucho, Sun/iPlanet, New Atlanta, ATG, Fujitsu, Lutris, Silverstream, the World Wide Web Consortium (W3C), and many others. Several low-cost plugins add support to Microsoft IIS and Zeus as well. They run on Windows, Unix/Linux, MacOS, VMS, and IBM mainframe operating systems. They are the single most popular application of the Java programming language. They are arguably the most popular choice for developing medium to large Web applications. They are used by the airline industry (most United Airlines and Delta Airlines Web sites), e-commerce (), online banking (First USA Bank, Banco Popular de Puerto Rico), Web search engines/portals (), large financial sites (American Century Investments), and hundreds of other sites that you visit every day.Of course, popularity alone is no proof of good technology. Numerous counter-examples abound. But our point is that you are not experimenting with a new and unproven technology when you work with server-side Java.Servlet和JSP技术简介1.1Servlet的功能Servlets是运行在Web或应用服务器上的Java程序，它是一个中间层，负责连接来自Web浏览器或其他HTTP客户端和HTTP服务器上的数据库或应用程序。
JSP技术简介及特点外文翻译
附录AJSP Technology Conspectus And Specialties The JSP (Java Server mix) technology is used by the Sun microsystem issued by the company to develop dynamic Web application technology. With its easy, cross-platform, in many dynamic Web application programming languages, in a short span of a few years, has formed a complete set of standards, and widely used in electronic commerce, etc. In China, the JSP now also got more extensive attention, get a good development, more and more dynamic website to JSP technology. The related technologies of JSP are briefly introduced.The JSP a simple technology can quickly and with the method of generating Web pages. Use the JSP technology Web page can be easily display dynamic content. The JSP technology are designed to make the construction based on Web applications easier and efficient, and these applications and various Web server, application server, the browser and development tools work together.The JSP technology isn't the only dynamic web technology, also not the first one, in the JSP technology existed before the emergence of several excellent dynamic web technology, such as CGI, ASP, etc. With the introduction of these technologies under dynamic web technology, the development and the JSP. TechnicalJSP the development background and development historyIn web brief history, from a world wide web that most of the network information static on stock transactions evolution to acquisition of an operation and infrastructure. In a variety of applications, may be used for based on Web client, look no restrictions.Based on the browser client applications than traditional based on client/server applications has several advantages. These benefits include almost no limit client access and extremely simplified application deployment and management (to update an application, management personnel only need to change the program on a server, not thousands of installation in client applications). So, the software industry is rapidly to build on the client browser multi-layer application.The rapid growth of exquisite based Web application requirements development of technical improvements. Static HTML to show relatively static content is right choice, The new challenge is to create the interaction based on Web applications, in these procedures, thecontent of a Web page is based on the user's request or the state of the system, and are not predefined characters.For the problem of an early solution is to use a CGI - BIN interface. Developers write to interface with the relevant procedures and separate based on Web applications, the latter through the Web server to invoke the former. This plan has serious problem -- each new extensible CGI requirements in a new process on the server. If multiple concurrent users access to this procedure, these processes will use the Web server of all available resources, and the performance of the system will be reduced to extremely low.Some Web server providers have to provide for their server by plugins "and" the API to simplify the Web application development. These solutions are associated with certain Web server, cannot solve the span multiple suppliers solutions. For example, Microsoft's Active Server mix (ASP) technology in the Web page to create dynamic content more easily, but also can work in Microsoft on Personal Web Server and IIS.There are other solutions, but cannot make an ordinary page designers can easily master. For example, such as the Servlet Java technologies can use Java language interaction application server code easier. Developers to write such Servlet to receive signals from the Web browser to generate an HTTP request, a dynamic response (may be inquires the database to finish the request), then send contain HTML or XML documents to the response of the browser.note: one is based on a Java Servlet Java technical operation in the server program (with different, the latter operating in the Applet browser end). In this book the Servlet chapter 4.Using this method, the entire page must have made in Java Servlet. If developers or Web managers want to adjust page, you'll have to edit and recompile the Servlet Java, even in logic has been able to run. Using this method, the dynamic content with the application of the page still need to develop skills.Obviously, what is needed is a industry to create dynamic content within the scope of the pages of the solution. This program will solve the current scheme are limited. As follows: can on any Web server or applications.will application page displays and separation.can rapidly developing and testing.simplify the interactive development based on Web application process.The JSP technology is designed to meet such requirements. The JSP specification is a Web server, application server, trading system and develop extensive cooperation between the tool suppliers. From this standard to develop the existing integration and balance of Java programming environment (for example, Java Servlet and JavaBeans) support techniques and tools. The result is a kind of new and developing method based on Web applications, using component-based application logic page designers with powerful functions.Overall Semantics of a JSP PageA JSP page implementation class defines a _jspService() method mapping from the request to the response object. Some details of this transformation are specific to the scripting language used (see Chapter JSP.9, “Scripting”). Most details are not language specific and are described in this chapter.The content of a JSP page is devoted largely to describing the data that is written into the output stream of the response. (The JSP container usually sends this data back to the client.) The description is based on a JspWriter object that is exposed through the implicit object out (see Section JSP.1.8.3, “Implicit Objects”). Its value varies:Initially, out is a new JspWriter object. This object may be different from the stream object returned from response.getWriter(), and may be considered to be interposed on the latter in order to implement buffering (see Section JSP.1.10.1, “The page Directive”). This is the initial out object. JSP page authors are prohibited from writing directly to either the PrintWriter or OutputStream associated with the ServletResponse.The JSP container should not invoke response.getWriter() until the time when the first portion of the content is to be sent to the client. This enables a number of uses of JSP, including using JSP as a language to “glue” actions that deliver binary content, or reliably forwarding to a servlet, or change dynamically the content type of the response before generating content. See Chapter JSP.4, “Internationalization Issues”.Within the body of some actions, out may be temporarily re-assigned to a different (nested) instance of a JspWriter object. Whether this is the case depends on the details of the action’s semantics. Typically the content of these temporary streams is appended to the stream previously referred to by out, and out is subsequently re-assigned to refer to the previous (nesting) stream. Such nested streams are always buffered, and require explicit flushing to a nesting stream or their contents will be discarded.If the initial out JspWriter object is buffered, then depending upon the value of the autoFlush attribute of the page directive, the content of that buffer will either be automaticallyflushed out to the ServletResponse output stream to obviate overflow, or an exception shall be thrown to signal buffer overflow. If the initial out JspWriter is unbuffered, then content written to it will be passed directly through to the ServletResponse output stream.A JSP page can also describe what should happen when some specific events occur. In JSP 2.1, the only events that can be described are the initialization and the destruction of the page. These events are described using “well-known method names” in declaration elements..JavaScript is used for the first kind is browser, the dynamic general purpose of client scripting language. Netscape first proposed in 1995, but its JavaScript LiveScript called. Then quickly Netscape LiveScript renamed JavaScript, Java developers with them from the same issued a statement. A statement Java and JavaScript will complement each other, but they are different, so the technology of the many dismissed the misunderstanding of the two technologies.JavaScript to create user interface control provides a scripting language. In fact, in the browser into the JavaScript code logic. It can support such effect: when the cursor on the Web page of a mobile user input validation or transform image.Microsoft also write out their JavaScript version and the JScript called. Microsoft and Netscape support JavaScript and JScript around a core characteristics and European Manufacturers is.md by (ECMA) standards organization, the control standard of scripting language. ECMA its scripting language ECMAScript named.Servlets and JSPs often include fragments of information that are common to an organization, such as logos, copyrights, trademarks, or navigation bars. The web application uses the include mechanisms to import the information wherever it is needed, since it is easier to change content in one place then to maintain it in every piece of code where it is used. Some of this information is static and either never or rarely changes, such as an organization's logo. In other cases, the information is more dynamic and changes often and unpredictably, such as a textual greeting that must be localized for each user. In both cases, you want to ensure that the servlet or JSP can evolve independently of its included content, and that the implementation of the servlet or JSP properly updates its included content as necessary.You want to include a resource that does not change very much (such as a page fragment that represents a header or footer) in a JSP. Use the include directive in the including JSP page, and give the included JSP segment a .jspf extension.You want to include content in a JSP each time it receives a request, rather than when the JSP is converted to a servlet. Use the jsp:include standard action.You want to include a file dynamically in a JSP, based on a value derived from a configuration file. Use the jsp:include standard action. Provide the value in an external properties file or as a configuration parameter in the deployment descriptor.You want to include a fragment of an XML file inside of a JSP document, or include a JSP page in XML syntax. Use the jsp:include standard action for the includes that you want to occur with each request of the JSP. Use the jsp:directive.include element if the include action should occur during the translation phase.You want to include a JSP segment from outside the including file's context. Use the c:importThe operation principle and the advantages of JSP tagsIn this section of the operating principle of simple introduction JSP and strengths.For the first time in a JSP documents requested by the engine, JSP Servlet is transformed into a document JSP. This engine is itself a Servlet. The operating process of the JSP shown below:(1) the JSP engine put the JSP files converting a Java source files (Servlet), if you find the files have any grammar mistake JSP, conversion process will interrupt, and to the server and client output error messages.(2) if converted, with the engine JSP javac Java source file compiler into a corresponding scale-up files.(3) to create a the Servlet (JSP page), the transformation of the Servlet jspInit () method was executed, jspInit () method in the life cycle of Servlet executed only once.(4) jspService () method invocation to the client requests. For each request, JSP engine to create a new thread for processing the request. If you have multiple clients and request the JSP files, JSP engine will create multiple threads. Each client requests a thread. To execute multi-thread can greatly reduce the requirement of system resources, improving the concurrency value and response time. But also should notice the multi-thread programming, due to the limited Servlet always in response to memory, so is very fast.(5) if the file has been modified. The JSP, server will be set according to the document to decide whether to recompile, if need to recompile, will replace the Servlet compile the memory and continue the process.(6) although the JSP efficiency is high, but at first when the need to convert and compile and some slight delay. In addition, if at any time due to reasons of system resources, JSP engine will in some way of uncertain Servlet will remove from memory. When this happens jspDestroy () method was first call.(7) and then Servlet examples were marked with "add" garbage collection. But in jspInit () some initialization work, if establish connection with database, or to establish a network connection, from a configuration file take some parameters, such as, in jspDestory () release of the corresponding resources.Based on a Java language has many other techniques JSP page dynamic characteristics, technical have embodied in the following aspects:One simplicity and effectivenessThe JSP dynamic web pages with the compilation of the static HTML pages of writing is very similar. Just in the original HTML page add JSP tags, or some of the proprietary scripting (this is not necessary). So, a familiar with HTML page write design personnel may be easily performed JSP page development. And the developers can not only, and write script by JSP tags used exclusively others have written parts to realize dynamic pages. So, an unfamiliar with the web developers scripting language, can use the JSP make beautiful dynamic pages. And this in other dynamic web development is impossible.Tow the independence of the programThe JSP are part of the family of the API Java, it has the general characteristics of the cross-platform Java program. In other words, is to have the procedure, namely the independence of the platform, 6 Write bided anywhere! .Three procedures compatibilityThe dynamic content can various JSP form, so it can show for all kinds of customers, namely from using HTML/DHTML browser to use various handheld wireless equipment WML (for example, mobile phones and pdas), personal digital equipment to use XML applications, all can use B2B JSP dynamic pages.Four program reusabilityIn the JSP page can not directly, but embedded scripting dynamic interaction will be cited as a component part. So, once such a component to write, it can be repeated several procedures, the program of the reusability. Now, a lot of standard JavaBeans library is a good example.附录BJSP技术简介及特点JSP（Java Server Pages）技术是由Sun公司发布的用于开发动态Web应用的一项技术。
JSP技术概述与应用框架外文翻译毕业设计
国际化与本地化的重要性：提高 用户体验，增强市场竞争力
添加标题
添加标题
添加标题
添加标题
本地化：根据不同国家和地区的 语言和文化环境，对JSP应用进行 定制和优化
国际化与本地化的实现方法：使 用国际化框架，如i18n，进行国 际化和本地化处理
翻译质量要求
准确性：确保翻译内容与原文意思一致，无错译、漏译现象 流畅性：翻译语言通顺，符合目标语言的表达习惯 专业性：翻译内容涉及专业术语，需准确翻译，不得随意更改 格式规范：翻译后的文档格式应与原文保持一致，包括字体、字号、行距等
PART 6
毕业设计流程与规范
选题与开题报告撰写
选题：选择与专 业相关的课题， 确保具有研究价 值和实际意义
特点：Spring MVC具有清晰的分层结构，易于扩展和维护，支持RESTful风格，支持 多种视图技术。
核心组件：Spring MVC的核心组件包括DispatcherServlet、HandlerMapping、 Controller、ViewResolver等。
应用场景：Spring MVC广泛应用于Web开发中，如企业级应用、电子商务、社交网站等。
JSP可以与其他 Java技术（如 Servlet、 JDBC、JNDI等） 无缝集成，实现 强大的Web应 用程序开发。
JSP工作原理
JSP是一种服务器端的Java技术，用于创 建动态网页。
JSP页面由HTML、Java代码和JSP标签组 成。
JSP页面在服务器上被编译成Java Servlet，然后由Servlet引擎执行。
翻译质量：准色等
翻译时间：根据毕业设计进度， 合理安排翻译时间
外文翻译---JSP简介
附录1JSP ProfileJSP (JavaServer Pages) is initiated by Sun Microsystems, Inc., with many companies to participate in the establishment of a dynamic web page technical standards. JSP technology somewhat similar to ASP technology, it is in the traditional HTML web page document (*. htm, *. html) to insert the Java programming paragraph (Scriptlet) and JSP tag (tag), thus JSP documents (*. jsp). Using JSP development of the Web application is cross-platform that can run on Linux, is also available for other operating systems. JSP technology to use the Java programming language prepared by the category of XML tags and scriptlets, to produce dynamic pages package processing logic. Page also visit by tags and scriptlets exist in the services side of the resources of logic. JSP page logic and web page design and display separation, support reusable component-based design, Web-based application development is rapid and easy.Web server in the face of visits JSP page request, the first implementation of the procedures of, and then together with the results of the implementation of JSP documents in HTML code with the return to the customer. Insert the Java programming operation of the database can be re-oriented websites, in order to achieve the establishment of dynamic pages needed to function.JSP and Java Servlet, is in the implementation of the server, usually returned to the client is an HTML text, as long as the client browser will be able to visit. JSP 1.0 specification of the final version is launched in September 1999, December has introduced 1.1 specifications. At present relatively new is JSP1.2 norms, JSP2.0 norms of the draft has also been introduced.JSP pages from HTML code and Java code embedded in one of the components. The server was in the pages of client requests after the Java code and then will generate the HTML pages to return to the client browser. Java Servlet JSP is the technical foundation and large-scale Web application development needs of Java Servlet and JSP support to complete. JSP with the Java technology easy to use, fully object-oriented, and a platform-independent and secure, mainly for all the characteristics of the Internet.JSP technology strength(1) time to prepare, run everywhere. At this point Java better than PHP, in addition to systems, the code not to make any changes.(2) the multi-platform support. Basically on all platforms of any development environment, in any environment for deployment in any environment in the expansion. Compared ASP / PHP limitations are obvious.(3) a strong scalability. From only a small Jar documents can run Servlet / JSP, to the multiple servers clustering and load balancing, to multiple Application for transaction processing, information processing, a server to numerous servers, Java shows a tremendous Vitality.(4) diversification and powerful development tools support. This is similar tothe ASP, Java already have many very good development tools, and many can be free, and many of them have been able to run on a variety of platforms under.JSP technology vulnerable(1) and the same ASP, Java is the advantage of some of its fatal problem. It is precisely because in order to cross-platform functionality, in order to extreme stretching capacity, greatly increasing the complexity of the product.(2) Java's speed is class to complete the permanent memory, so in some cases by the use of memory compared to the number of users is indeed a "minimum cost performance." On the other hand, it also needs disk space to store a series of. Java documents and. Class, as well as the corresponding versions of documents.JSP six built-in objects:request, response, out, session, application, config, pagecontext, page, exception.1. Request for:The object of the package of information submitted by users, by calling the object corresponding way to access the information package, namely the use of the target users can access the information.2. Response object:The customer's request dynamic response to the client sent the data.3. session object1. What is the session: session object is a built-in objects JSP, it in the first JSP pages loaded automatically create, complete the conversation of management.From a customer to open a browser and connect to the server, to close the browser, leaving the end of this server, known as a conversation. When a customer visits a server, the server may be a few pages link between repeatedly, repeatedly refresh a page, the server should be through some kind of way to know this is the same client, which requires session object.2. session object ID: When a customer's first visit to a server on the JSP pages, JSP engines produce a session object, and assigned a String type of ID number, JSP engine at the same time, the ID number sent to the client, stored in Cookie, this session objects, and customers on the establishment of a one-to-one relationship. When a customer to connect to the server of the other pages, customers no longer allocated to the new session object, until, close your browser, the client-server object to cancel the session, and the conversation, and customer relationship disappeared. When a customer re-open the browser to connect to the server, the server for the customer to create a new session object.4. aplication target1. What is the application:Servers have launched after the application object, when a customer to visit the site between the various pages here, this application objects are the same, until the server is down. But with the session difference is that all customers of the application objects are the same, that is, all customers share this built-in application objects.2. application objects commonly used methods:(1) public void setAttribute (String key, Object obj): Object specified parameters will be the object obj added to the application object, and to add the subject of the designation of a keyword index.(2) public Object getAttribute (String key): access to application objects containing keywords for.5. out targetsout as a target output flow, used to client output data. out targets for the output data.6. Cookie1. What is Cookie: Cookie is stored in Web server on the user's hard drive section of the text. Cookie allow a Web site on the user's computer to store information on and then get back to it. For example, a Web site may be generated for each visitor a unique ID, and then to Cookie in the form of documents stored in each user's machine. If you use IE browser to visit Web, you will see all stored on your hard drive on the Cookie. They are most often stored in places: c: \ windows \ cookies (in Window2000 is in the C: \ Documents and Settings \ your user name \ Cookies) Cookie is "keyword key = value value" to preserve the format of the record.2. Targets the creation of a Cookie, Cookie object called the constructor can create a Cookie. Cookie object constructor has two string parameters: Cookie Cookie name and value. Cookie c = new Cookie ( "username", "john");3. If the JSP in the package good Cookie object to send to the client, the use of the response addCookie () method.Format: response.addCookie (c)4. Save to read the client's Cookie, the use of the object request getCookies () method will be implemented in all client came to an array of Cookie objects in the form of order, to meet the need to remove the Cookie object, it is necessary to compare an array cycle Each target keywords.JSP简介JSP(JavaServer Pages)是由Sun Microsystems公司倡导、许多公司参与一起建立的一种动态网页技术标准。
JSP的技术发展-中英文文献翻译
THE TECHNIQUE DEVELOPMENT HISTORY OF JSPBy:Kathy Sierra and Bert BatesSource:Servlet&JSPThe Java Server Pages( JSP) is a kind of according to web of the script plait distance technique, similar carries the script language of Java in the server of the Netscape company of server- side JavaScript( SSJS) and the Active Server Pages(ASP) of the Microsoft. JSP compares the SSJS and ASP to have better can expand sex, and it is no more exclusive than any factory or some one particular server of Web. Though the norm of JSP is to be draw up by the Sun company of, any factory can carry out the JSP on own system.The After Sun release the JSP( the Java Server Pages) formally, the this kind of new Web application development technique very quickly caused the people's concern. JSP provided a special development environment for the Web application that establishes the high dynamic state. According to the Sun parlance, the JSP can adapt to include the Apache WebServer, IIS4.0 on the market at inside of 85% server product.This chapter will introduce the related knowledge of JSP and Databases, and JavaBean related contents, is all certainly rougher introduction among them basic contents, say perhaps to is a Guide only, if the reader needs the more detailed information, pleasing the book of consult the homologous JSP.1.1 GENERALIZEThe JSP(Java Server Pages) is from the company of Sun Microsystems initiate, the many companies the participate to the build up the together of the a kind the of dynamic the state web the page technique standard, the it have the it in the construction the of the dynamic state the web page the strong but the do not the especially of the function. JSP and the technique of ASP of the Microsoft is very alike. Both all provide the ability that mixes with a certain procedure code and is explain by the language engine to carry out the procedure code in the code of HTML. Underneath we are simple of carry on the introduction to it.JSP pages are translated into servlets. So, fundamentally, any task JSP pages can perform could also be accomplished by servlets. However, this underlying equivalence does not mean that servlets and JSP pages are equally appropriate in all scenarios. The issue is not the power of the technology, it is the convenience, productivity, and maintainability of one or the other. After all, anything you can do on a particular computer platform in the Java programming language you could also do in assembly language. But it still matters which you choose.JSP provides the following benefits over servlets alone:• It is easier to write and maintain the HTML. Your static code is ordinary HTML: no extra backslashes, no double quotes, and no lurking Java syntax.• You can use standard Web-site development tools. Even HTML tools that know nothing about JSP can be used because they simply ignore the JSP tags.• You can divide up your development team. The Java programmers can work on the dynamic code. The Web developers can concentrate on the presentation layer. On large projects, this division is very important. Depending on the size of your team and the complexity of your project, you can enforce a weaker or stronger separation between the static HTML and the dynamic content.Now, this discussion is not to say that you should stop using servlets and use only JSP instead. By no means. Almost all projects will use both. For some requests in your project, you will use servlets. For others, you will use JSP. For still others, you will combine them with the MVC architecture . You want the appropriate tool for the job, and servlets, by themselves, do not complete your toolkit.1.2 SOURCE OF JSPThe technique of JSP of the company of Sun, making the page of Web develop the personnel can use the HTML perhaps marking of XML to design to turn the end page with format. Use the perhaps small script future life of marking of JSP becomes the dynamic state on the page contents.( the contents changes according to the claim of)The Java Servlet is a technical foundation of JSP, and the large Web applies the development of the procedure to need the Java Servlet to match with with the JSP and then can complete, this name of Servlet comes from the Applet, the local translation method of now is a lot of, this book in order not to misconstruction, decide the direct adoption Servlet but don't do any translation, if reader would like to, can call it as" small service procedure". The Servlet is similar to traditional CGI, ISAPI, NSAPI etc. Web procedure development the function of the tool in fact, at use the Java Servlet hereafter, the customer need not use again the lowly method of CGI of efficiency, also need not use only the ability come to born page of Web of dynamic state in the method of API that a certain fixed Web server terrace circulate. Many servers of Web all support the Servlet, even not support the Servlet server of Web directly and can also pass the additional applied server and the mold pieces to support the Servlet. Receive benefit in the characteristic of the Java cross-platform, the Servlet is also a terrace irrelevant, actually, as long as match the norm of Java Servlet, the Servlet is complete to have nothing to do with terrace and is to have nothing to do with server of Web. Because the Java Servlet is internal to provide the service by the line distance, need not start a progress to the each claimses, and makeuse of the multi-threading mechanism can at the same time for several claim service, therefore the efficiency of Java Servlet is very high.But the Java Servlet also is not to has no weakness, similar to traditional CGI, ISAPI, the NSAPI method, the Java Servlet is to make use of to output the HTML language sentence to carry out the dynamic state web page of, if develop the whole website with the Java Servlet, the integration process of the dynamic state part and the static state page is an evil-foreboding dream simply. For solving this kind of weakness of the Java Servlet, the SUN released the JSP.A number of years ago, Marty was invited to attend a small 20-person industry roundtable discussion on software technology. Sitting in the seat next to Marty was James Gosling, inventor of the Java programming language. Sitting several seats away was a high-level manager from a very large software company in Redmond, Washington. During the discussion, the moderator brought up the subject of Jini, which at that time was a new Java technology. The moderator asked the manager what he thought of it, and the manager responded that it was too early to tell, but that it seemed to be an excellent idea. He went on to say that they would keep an eye on it, and if it seemed to be catching on, they would follow his company's usual "embrace and extend" strategy. At this point, Gosling lightheartedly interjected "You mean disgrace and distend."Now, the grievance that Gosling was airing was that he felt that this company would take technology from other companies and suborn it for their own purposes. But guess what? The shoe is on the other foot here. The Java community did not invent the idea of designing pages as a mixture of static HTML and dynamic code marked with special tags. For example, Cold Fusion did it years earlier. Even ASP (a product from the very software company of the aforementioned manager) popularized this approach before JSP came along and decided to jump on the bandwagon. In fact, JSP not only adopted the general idea, it even used many of the same special tags as ASP did.The JSP is an establishment at the model of Java servlets on of the expression layer technique, it makes the plait write the HTML to become more simple.Be like the SSJS, it also allows you carry the static state HTML contents and servers the script mix to put together the born dynamic state exportation. JSP the script language that the Java is the tacit approval, however, be like the ASP and can use other languages( such as JavaScript and VBScript), the norm of JSP also allows to use other languages.1.3JSP CHARACTERISTICSIs a service according to the script language in some one language of the statures system this kind of discuss, the JSP should be see make is a kind of script language. However, be a kind of script language, the JSP seemed to be too strong again, almost can use all Javas in theJSP.Be a kind of according to text originally of, take manifestation as the central development technique, the JSP provided all advantages of the Java Servlet, and, when combine with a JavaBeans together, providing a kind of make contents and manifestation that simple way that logic separate. Separate the contents and advantage of logical manifestations is, the personnel who renews the page external appearance need not know the code of Java, and renew the JavaBeans personnel also need not be design the web page of expert in hand, can use to take the page of JavaBeans JSP to define the template of Web, to build up a from have the alike external appearance of the website that page constitute. JavaBeans completes the data to provide, having no code of Java in the template thus, this means that these templates can be written the personnel by a HTML plait to support. Certainly, can also make use of the Java Servlet to control the logic of the website, adjust through the Java Servlet to use the way of the document of JSP to separate website of logic and contents.Generally speaking, in actual engine of JSP, the page of JSP is the edit and translate type while carry out, not explain the type of. Explain the dynamic state web page development tool of the type, such as ASP, PHP3 etc., because speed etc. reason, have already can't satisfy current the large electronic commerce needs appliedly, traditional development techniques are all at to edit and translate the executive way change, such as the ASP → ASP+;PHP3 → PHP4.In the JSP norm book, did not request the procedure in the JSP code part( be called the Scriptlet) and must write with the Java definitely. Actually, have some engines of JSP are adoptive other script languages such as the EMAC- Script, etc., but actually this a few script languages also are to set up on the Java, edit and translate for the Servlet to carry out of. Write according to the norm of JSP, have no Scriptlet of relation with Java also is can of, however, mainly lie in the ability and JavaBeans, the Enterprise JavaBeanses because of the JSP strong function to work together, so even is the Scriptlet part not to use the Java, edit and translate of performance code also should is related with Java.1.4JSP MECHANISMTo comprehend the JSP how unite the technical advantage that above various speak of, come to carry out various result easily, the customer must understand the differentiation of" the module develops for the web page of the center" and" the page develops for the web page of the center" first.The SSJS and ASP are all in several year ago to release, the network of that time is still very young, no one knows to still have in addition to making all business, datas and the expression logic enter the original web page entirely heap what better solve the method. This kind of model that take page as the center studies and gets the very fast development easily.However, along with change of time, the people know that this kind of method is unwell in set up large, the Web that can upgrade applies the procedure. The expression logic write in the script environment was lock in the page, only passing to shear to slice and glue to stick then can drive heavy use. Express the logic to usually mix together with business and the data logics, when this makes be the procedure member to try to change an external appearance that applies the procedure but do not want to break with its llied business logic, apply the procedure of maintenance be like to walk the similar difficulty on the eggshell. In fact in the business enterprise, heavy use the application of the module already through very mature, no one would like to rewrite those logics for their applied procedure.HTML and sketch the designer handed over to the implement work of their design the Web plait the one who write, make they have to double work- Usually is the handicraft plait to write, because have no fit tool and can carry the script and the HTML contents knot to the server to put together. Chien but speech, apply the complexity of the procedure along with the Web to promote continuously, the development method that take page as the center limits sex to become to get up obviously.At the same time, the people always at look for the better method of build up the Web application procedure, the module spreads in customer's machine/ server the realm. JavaBeans and ActiveX were published the company to expand to apply the procedure developer for Java and Windows to use to come to develop the complicated procedure quickly by" the fast application procedure development"( RAD) tool. These techniques make the expert in the some realm be able to write the module for the perpendicular application plait in the skill area, but the developer can go fetch the usage directly but need not control the expertise of this realm.Be a kind of take module as the central development terrace, the JSP appeared. It with the JavaBeans and Enterprise JavaBeans( EJB) module includes the model of the business and the data logic for foundation, provide a great deal of label and a script terraces to use to come to show in the HTML page from the contents of JavaBeans creation or send a present in return. Because of the property that regards the module as the center of the JSP, it can drive Java and not the developer of Java uses equally. Not the developer of Java can pass the JSP label( Tags) to use the JavaBeans that the deluxe developer of Java establish. The developer of Java not only can establish and use the JavaBeans, but also can use the language of Java to come to control more accurately in the JSP page according to the expression logic of the first floor JavaBeans.See now how JSP is handle claim of HTTP. In basic claim model, a claim directly was send to JSP page in. The code of JSP controls to carry on hour of the logic processing and module of JavaBeanses' hand over with each other, and the manifestation result in dynamic state bornly, mixing with the HTML page of the static state HTML code. The Beans can beJavaBeans or module of EJBs. Moreover, the more complicated claim model can see make from is request other JSP pages of the page call sign or Java Servlets.The engine of JSP wants to chase the code of Java that the label of JSP, code of Java in the JSP page even all converts into the big piece together with the static state HTML contents actually. These codes piece was organized the Java Servlet that customer can not see to go to by the engine of JSP, then the Servlet edits and translate them automatically byte code of Java.Thus, the visitant that is the website requests a JSP page, under the condition of it is not knowing, an already born, the Servlet actual full general that prepared to edit and translate completes all works, very concealment but again and efficiently. The Servlet is to edit and translate of, so the code of JSP in the web page does not need when the every time requests that page is explain. The engine of JSP need to be edit and translate after Servlet the code end is modify only once, then this Servlet that editted and translate can be carry out. The in view of the fact JSP engine auto is born to edit and translate the Servlet also, need not procedure member begins to edit and translate the code, so the JSP can bring vivid sex that function and fast developments need that you are efficiently.Compared with the traditional CGI, the JSP has the equal advantage. First, on the speed, the traditional procedure of CGI needs to use the standard importation of the system to output the equipments to carry out the dynamic state web page born, but the JSP is direct is mutually the connection with server. And say for the CGI, each interview needs to add to add a progress to handle, the progress build up and destroy by burning constantly and will be a not small burden for calculator of be the server of Web. The next in order, the JSP is specialized to develop but design for the Web of, its purpose is for building up according to the Web applied procedure, included the norm and the tool of a the whole set. Use the technique of JSP can combine a lot of JSP pages to become a Web application procedure very expediently.JSP的技术发展历史作者：Kathy Sierra and Bert Bates来源：Servlet&JSPJava Server Pages(JSP)是一种基于web的脚本编程技术，类似于网景公司的服务器端Java脚本语言——server-side JavaScript(SSJS)和微软的Active Server Pages(ASP)。
英文文献及翻译(Servlet和JSP技术简述)
An Overview of Servlet and JSP TechnologyNagle ,WiegleyAbstract: Servlet program running in the server-side, dynamically generated Web page with the traditional CGI and many other similar compared to CGI technology, Java Servlet with a more efficient, easier to use, more powerful and has better portability, more savings to invest. .Keywords: JSP Technology;Servlet;HTTP server1. A Servlet's JobServlets are Java programs that run on Web or application servers, acting as a middle layer between requests coming from Web browsers or other HTTP clients and databases or applications on the HTTP server. Their job is to perform the following tasks, as illustrated in Figure 1-1.Figure 1-1Web middleware role1.1 Read the explicit data sent by the client.The end user normally enters this data in an HTML form on a Web page. However, the data could also come from an applet or a custom HTTP client program.1.2 Read the implicit HTTP request data sent by the browser.Figure 1-1 shows a single arrow going from the client to the Web server (the layer where servlets and JSP execute), but there are really two varieties of data: the explicit data that the end user enters in a form and the behind-the-scenes HTTP information. Both varieties are critical. The HTTP information includes cookies, information about media types and compression schemes the browser understands, and so on.1.3 Generate the results.This process may require talking to a database, executing an RMI or EJB call, invoking a Web service, or computing the response directly. Your real data may be in a relational database. Fine. But your database probably doesn't speak HTTP or return results in HTML, so the Web browser can't talk directly to the database. Even if it could, for security reasons, you probably would not want it to. The same argument applies to most other applications.You need the Web middle layer to extract the results inside a document.1.4 Send the explicit data (i.e., the document) to the client.This document can be sent in a variety of formats, including text (HTML or XML), binary (GIF images), or even a compressed format like gzip that is layered on top of some other underlying format. But, HTML is by far the most common format, so an important servlet/JSP task is to wrap the results inside of HTML.1.5 Send the implicit HTTP response data.Figure 1-1 shows a single arrow going from the Web middle layer (the servlet or JSP page) to the client. But, there are really two varieties of data sent: the document itself and the behind-the-scenes HTTP information. Again, both varieties are critical to effective development. Sending HTTP response data involves telling the browser or other client what type of document is being returned (e.g., HTML), setting cookies and caching parameters, and other such tasks.2 Why Build Web Pages Dynamically?many client requests can be satisfied by prebuilt documents, and the server would handle these requests without invoking servlets. In many cases, however, a static result is not sufficient, and a page needs to be generated for each request. There are a number of reasons why Web pages need to be built on-the-fly:2.1 The Web page is based on data sent by the client.For instance, the results page from search engines and order-confirmation pages at online stores are specific to particular user requests. You don't know what to display until you read the data that the user submits. Just remember that the user submits two kinds of data: explicit (i.e., HTML form data) and implicit (i.e., HTTP request headers). Either kind of input can be used to build the output page. In particular, it is quite common to build a user-specific page based on a cookie value.2.2 The Web page is derived from data that changes frequently.If the page changes for every request, then you certainly need to build the response at request time. If it changes only periodically, however, you could do it two ways: you could periodically build a new Web page on the server (independently of client requests), or you could wait and only build the page when the user requests it. The right approach depends on the situation, but sometimes it is more convenient to do the latter: wait for the user request. For example, a weather report or news headlines site might build the pages dynamically, perhaps returning a previously built page if that page is still up to date.2.3 The Web page uses information from corporate databases or other server-side sources.If the information is in a database, you need server-side processing even if the client is using dynamic Web content such as an applet. Imagine using an applet by itself for a search engine site:"Downloading 50 terabyte applet, please wait!" Obviously, that is silly; you need to talk to the database. Going from the client to the Web tier to the database (a three-tier approach) instead of from an applet directly to a database (a two-tier approach) provides increased flexibility and security with little or no performance penalty. After all, the database call is usually the rate-limiting step, so going through the Web server does not slow things down. In fact, a three-tier approach is often faster because the middle tier can perform caching and connection pooling.In principle, servlets are not restricted to Web or application servers that handle HTTP requests but can be used for other types of servers as well. For example, servlets could be embedded in FTP or mail servers to extend their functionality. And, a servlet API for SIP (Session Initiation Protocol) servers was recently standardized (see /en/jsr/detail?id=116). In practice, however, this use of servlets has not caught on, and we'll only be discussing HTTP servlets.3 The Advantages of Servlets Over "Traditional" CGIJava servlets are more efficient, easier to use, more powerful, more portable, safer, and cheaper than traditional CGI and many alternative CGI-like technologies. 3.1 EfficientWith traditional CGI, a new process is started for each HTTP request. If the CGI program itself is relatively short, the overhead of starting the process can dominate the execution time. With servlets, the Java virtual machine stays running and handles each request with a lightweight Java thread, not a heavyweight operating system process. Similarly, in traditional CGI, if there are N requests to the same CGI program, the code for the CGI program is loaded into memory N times. With servlets, however, there would be N threads, but only a single copy of the servlet class would be loaded. This approach reduces server memory requirements and saves time by instantiating fewer objects. Finally, when a CGI program finishes handling a request, the program terminates. This approach makes it difficult to cache computations, keep database connections open, and perform other optimizations that rely on persistent data. Servlets, however, remain in memory even after they complete a response, so it is straightforward to store arbitrarily complex data between client requests.3.2 ConvenientServlets have an extensive infrastructure for automatically parsing and decoding HTML form data, reading and setting HTTP headers, handling cookies, tracking sessions, and many other such high-level utilities. In CGI, you have to do much of this yourself. Besides, if you already know the Java programming language, why learn Perl too? You're already convinced that Java technology makes for more reliable and reusable code than does Visual Basic, VBScript, or C++. Why go back to those languages for server-side programming?3.3 PowerfulServlets support several capabilities that are difficult or impossible to accomplishwith regular CGI. Servlets can talk directly to the Web server, whereas regular CGI programs cannot, at least not without using a server-specific API. Communicating with the Web server makes it easier to translate relative URLs into concrete path names, for instance. Multiple servlets can also share data, making it easy to implement database connection pooling and similar resource-sharing optimizations. Servlets can also maintain information from request to request, simplifying techniques like session tracking and caching of previous computations.3.4 PortableServlets are written in the Java programming language and follow a standard API. Servlets are supported directly or by a plugin on virtually every major Web server. Consequently, servlets written for, say, Macromedia JRun can run virtually unchanged on Apache Tomcat, Microsoft Internet Information Server (with a separate plugin), IBM WebSphere, iPlanet Enterprise Server, Oracle9i AS, or StarNine WebStar. They are part of the Java 2 Platform, Enterprise Edition (J2EE; see /j2ee/), so industry support for servlets is becoming even more pervasive.3.5 InexpensiveA number of free or very inexpensive Web servers are good for development use or deployment of low- or medium-volume Web sites. Thus, with servlets and JSP you can start with a free or inexpensive server and migrate to more expensive servers with high-performance capabilities or advanced administration utilities only after your project meets initial success. This is in contrast to many of the other CGI alternatives, which require a significant initial investment for the purchase of a proprietary package.Price and portability are somewhat connected. For example, Marty tries to keep track of the countries of readers that send him questions by email. India was near the top of the list, probably behind the U.S. Marty also taught one of his JSP and servlet training courses (see /) in Manila, and there was great interest in servlet and JSP technology there.Now, why are India and the Philippines both so interested? We surmise that the answer is twofold. First, both countries have large pools of well-educated software developers. Second, both countries have (or had, at that time) highly unfavorable currency exchange rates against the U.S. dollar. So, buying a special-purpose Web server from a U.S. company consumed a large part of early project funds.But, with servlets and JSP, they could start with a free server: Apache Tomcat (either standalone, embedded in the regular Apache Web server, or embedded in Microsoft IIS). Once the project starts to become successful, they could move to a server like Caucho Resin that had higher performance and easier administration but that is not free. But none of their servlets or JSP pages have to be rewritten. If their project becomes even larger, they might want to move to a distributed (clustered) environment. No problem: they could move to Macromedia JRun Professional, whichsupports distributed applications (Web farms). Again, none of their servlets or JSP pages have to be rewritten. If the project becomes quite large and complex, they might want to use Enterprise JavaBeans (EJB) to encapsulate their business logic. So, they might switch to BEA WebLogic or Oracle9i AS. Again, none of their servlets or JSP pages have to be rewritten. Finally, if their project becomes even bigger, they might move it off of their Linux box and onto an IBM mainframe running IBM WebSphere. But once again, none of their servlets or JSP pages have to be rewritten.3.6 SecureOne of the main sources of vulnerabilities in traditional CGI stems from the fact that the programs are often executed by general-purpose operating system shells. So, the CGI programmer must be careful to filter out characters such as backquotes and semicolons that are treated specially by the shell. Implementing this precaution is harder than one might think, and weaknesses stemming from this problem are constantly being uncovered in widely used CGI libraries.A second source of problems is the fact that some CGI programs are processed by languages that do not automatically check array or string bounds. For example, in C and C++ it is perfectly legal to allocate a 100-element array and then write into the 999th "element," which is really some random part of program memory. So, programmers who forget to perform this check open up their system to deliberate or accidental buffer overflow attacks.Servlets suffer from neither of these problems. Even if a servlet executes a system call (e.g., with Runtime.exec or JNI) to invoke a program on the local operating system, it does not use a shell to do so. And, of course, array bounds checking and other memory protection features are a central part of the Java programming language.3.7 MainstreamThere are a lot of good technologies out there. But if vendors don't support them and developers don't know how to use them, what good are they? Servlet and JSP technology is supported by servers from Apache, Oracle, IBM, Sybase, BEA, Macromedia, Caucho, Sun/iPlanet, New Atlanta, ATG, Fujitsu, Lutris, Silverstream, the World Wide Web Consortium (W3C), and many others. Several low-cost plugins add support to Microsoft IIS and Zeus as well. They run on Windows, Unix/Linux, MacOS, VMS, and IBM mainframe operating systems. They are the single most popular application of the Java programming language. They are arguably the most popular choice for developing medium to large Web applications. They are used by the airline industry (most United Airlines and Delta Airlines Web sites), e-commerce (), online banking (First USA Bank, Banco Popular de Puerto Rico), Web search engines/portals (), large financial sites (American Century Investments), and hundreds of other sites that you visit every day.Of course, popularity alone is no proof of good technology. Numerous counter-examples abound. But our point is that you are not experimenting with a newand unproven technology when you work with server-side Java.References：[1]Clifton G.M. Branham, Arthur Jonathan .Servlets and JSP in an undergraduate database course[J].Proceedings of the International Conference on Parallel and Distributed Processing Techniques and Applications,2003(3):1490-1496.[2]Kirkegaard, Christian.Static analysis for Java servlets and JSP[J].Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics),2006(4):336-352.[3]Nakaike,Takuya.JSP Splitting for improving execution performance[J].Proceedings - International Symposium on Applications and the Internet,2004[8]:117-126.[4]Hassan, Doaa .Developing a security typed java servlet[J].Proceedings - The 4th International Symposium on Information Assurance and Security,2008(10):215-220.Servlet和JSP技术简述Nagle ，Wiegley摘要：Servlet程序在服务器端运行，动态地生成Web页面与传统的CGI和许多其他类似CGI的技术相比，Java Servlet具有更高的效率，更容易使用，功能更强大，具有更好的可移植性，更节省投资。
Servlet和JSP技术简述(英文翻译)
An Overview of Servlet and JSP TechnologyGildas Avoine and Philippe OechslinEPFL, Lausanne, Switzerland1.1HISTORY OF JSPThe Java Server Pages( JSP) is a kind of according to web of the script plait distance technique, similar carries the script language of Java in the server of the Netscape company of server- side JavaScript( SSJS) and the Active Server Pages(ASP) of the Microsoft. JSP compares the SSJS and ASP to have better can expand sex, and it is no more exclusive than any factory or some one particular server of Web. Though the norm of JSP is to be draw up by the Sun company of, any factory can carry out the JSP on own system.The After Sun release the JSP( the Java Server Pages) formally, the this kind of new Web application development technique very quickly caused the people's concern. JSP provided a special development environment for the Web application that establishes the high dynamic state. According to the Sun parlance, the JSP can adapt to include the Apache WebServer, IIS4.0 on the market at inside of 85% server product.This chapter will introduce the related knowledge of JSP and Databases, and JavaBean related contents, is all certainly rougher introduction among them basic contents, say perhaps to is a Guide only, if the reader needs the more detailed information, pleasing the book of consult the homologous JSP.1.1.1 GENERALIZEThe JSP(Java Server Pages) is from the company of Sun Microsystems initiate, the many companies the participate to the build up the together of the a kind the of dynamic the state web the page technique standard, the it have the it in the construction the of the dynamic state the web page the strong but the do not the especially of the function. JSP and the technique of ASP of the Microsoft is very alike. Both all provide the ability that mixes with a certain procedure code and is explain by the language engine to carry out the procedure code in the code of HTML. Underneath we are simple of carry on the introduction to it.JSP pages are translated into servlets. So, fundamentally, any task JSP pages canperform could also be accomplished by servlets. However, this underlying equivalence does not mean that servlets and JSP pages are equally appropriate in all scenarios. The issue is not the power of the technology, it is the convenience, productivity, and maintainability of one or the other. After all, anything you can do on a particular computer platform in the Java programming language you could also do in assembly language. But it still matters which you choose.JSP provides the following benefits over servlets alone:• It is easier to write and maintain the HTML. Your static code is ordinary HTML: no extra backslashes, no double quotes, and no lurking Java syntax.• You can use standard Web-site development tools. Even HTML tools that know nothing about JSP can be used because they simply ignore the JSP tags.• You can divide up your development team. The Java programmers can work on the dynamic code. The Web developers can concentrate on the presentation layer. On large projects, this division is very important. Depending on the size of your team and the complexity of your project, you can enforce a weaker or stronger separation between the static HTML and the dynamic content.Now, this discussion is not to say that you should stop using servlets and use only JSP instead. By no means. Almost all projects will use both. For some requests in your project, you will use servlets. For others, you will use JSP. For still others, you will combine them with the MVC architecture . You want the appropriate tool for the job, and servlets, by themselves, do not complete your toolkit.1.1.2 SOURCE OF JSPThe technique of JSP of the company of Sun, making the page of Web develop the personnel can use the HTML perhaps marking of XML to design to turn the end page with format. Use the perhaps small script future life of marking of JSP becomes the dynamic state on the page contents.( the contents changes according to the claim of)The Java Servlet is a technical foundation of JSP, and the large Web applies the development of the procedure to need the Java Servlet to match with with the JSP and then can complete, this name of Servlet comes from the Applet, the local translation method of now is a lot of, this book in order not to misconstruction, decide the direct adoption Servlet but don't do any translation, if reader would like to, can call it as" small service procedure". The Servlet is similar to traditional CGI, ISAPI, NSAPI etc. Web procedure development the function of the tool in fact, at use the Java Servlethereafter, the customer need not use again the lowly method of CGI of efficiency, also need not use only the ability come to born page of Web of dynamic state in the method of API that a certain fixed Web server terrace circulate. Many servers of Web all support the Servlet, even not support the Servlet server of Web directly and can also pass the additional applied server and the mold pieces to support the Servlet. Receive benefit in the characteristic of the Java cross-platform, the Servlet is also a terrace irrelevant, actually, as long as match the norm of Java Servlet, the Servlet is complete to have nothing to do with terrace and is to have nothing to do with server of Web. Because the Java Servlet is internal to provide the service by the line distance, need not start a progress to the each claimses, and make use of the multi-threading mechanism can at the same time for several claim service, therefore the efficiency of Java Servlet is very high.But the Java Servlet also is not to has no weakness, similar to traditional CGI, ISAPI, the NSAPI method, the Java Servlet is to make use of to output the HTML language sentence to carry out the dynamic state web page of, if develop the whole website with the Java Servlet, the integration process of the dynamic state part and the static state page is an evil-foreboding dream simply. For solving this kind of weakness of the Java Servlet, the SUN released the JSP.A number of years ago, Marty was invited to attend a small 20-person industry roundtable discussion on software technology. Sitting in the seat next to Marty was James Gosling, inventor of the Java programming language. Sitting several seats away was a high-level manager from a very large software company in Redmond, Washington. During the discussion, the moderator brought up the subject of Jini, which at that time was a new Java technology. The moderator asked the manager what he thought of it, and the manager responded that it was too early to tell, but that it seemed to be an excellent idea. He went on to say that they would keep an eye on it, and if it seemed to be catching on, they would follow his company's usual "embrace and extend" strategy. At this point, Gosling lightheartedly interjected "You mean disgrace and distend."Now, the grievance that Gosling was airing was that he felt that this company would take technology from other companies and suborn it for their own purposes. But guess what? The shoe is on the other foot here. The Java community did not invent the idea of designing pages as a mixture of static HTML and dynamic code marked with special tags. For example, Cold Fusion did it years earlier. Even ASP (aproduct from the very software company of the aforementioned manager) popularized this approach before JSP came along and decided to jump on the bandwagon. In fact, JSP not only adopted the general idea, it even used many of the same special tags as ASP did.The JSP is an establishment at the model of Java servlets on of the expression layer technique, it makes the plait write the HTML to become more simple.Be like the SSJS, it also allows you carry the static state HTML contents and servers the script mix to put together the born dynamic state exportation. JSP the script language that the Java is the tacit approval, however, be like the ASP and can use other languages( such as JavaScript and VBScript), the norm of JSP also allows to use other languages.1.1.3 JSP CHARACTERISTICSIs a service according to the script language in some one language of the statures system this kind of discuss, the JSP should be see make is a kind of script language. However, be a kind of script language, the JSP seemed to be too strong again, almost can use all Javas in the JSP.Be a kind of according to text originally of, take manifestation as the central development technique, the JSP provided all advantages of the Java Servlet, and, when combine with a JavaBeans together, providing a kind of make contents and manifestation that simple way that logic separate. Separate the contents and advantage of logical manifestations is, the personnel who renews the page external appearance need not know the code of Java, and renew the JavaBeans personnel also need not be design the web page of expert in hand, can use to take the page of JavaBeans JSP to define the template of Web, to build up a from have the alike external appearance of the website that page constitute. JavaBeans completes the data to provide, having no code of Java in the template thus, this means that these templates can be written the personnel by a HTML plait to support. Certainly, can also make use of the Java Servlet to control the logic of the website, adjust through the Java Servlet to use the way of the document of JSP to separate website of logic and contents.Generally speaking, in actual engine of JSP, the page of JSP is the edit and translate type while carry out, not explain the type of. Explain the dynamic state web page development tool of the type, such as ASP, PHP3 etc., because speed etc. reason, have already can't satisfy current the large electronic commerce needsappliedly, traditional development techniques are all at to edit and translate the executive way change, such as the ASP → ASP+;PHP3 → PHP4.In the JSP norm book, did not request the procedure in the JSP code part( be called the Scriptlet) and must write with the Java definitely. Actually, have some engines of JSP are adoptive other script languages such as the EMAC- Script, etc., but actually this a few script languages also are to set up on the Java, edit and translate for the Servlet to carry out of. Write according to the norm of JSP, have no Scriptlet of relation with Java also is can of, however, mainly lie in the ability and JavaBeans, the Enterprise JavaBeanses because of the JSP strong function to work together, so even is the Scriptlet part not to use the Java, edit and translate of performance code also should is related with Java.1.1.4 JSP MECHANISMTo comprehend the JSP how unite the technical advantage that above various speak of, come to carry out various result easily, the customer must understand the differentiation of" the module develops for the web page of the center" and" the page develops for the web page of the center" first.The SSJS and ASP are all in several year ago to release, the network of that time is still very young, no one knows to still have in addition to making all business, datas and the expression logic enter the original web page entirely heap what better solve the method. This kind of model that take page as the center studies and gets the very fast development easily. However, along with change of time, the people know that this kind of method is unwell in set up large, the Web that can upgrade applies the procedure. The expression logic write in the script environment was lock in the page, only passing to shear to slice and glue to stick then can drive heavy use. Express the logic to usually mix together with business and the data logics, when this makes be the procedure member to try to change an external appearance that applies the procedure but do not want to break with its llied business logic, apply the procedure of maintenance be like to walk the similar difficulty on the eggshell. In fact in the business enterprise, heavy use the application of the module already through very mature, no one would like to rewrite those logics for their applied procedure.HTMLand sketch the designer handed over to the implement work of their design the Web plait the one who write, make they have to double work- Usually is the handicraft plait to write, because have no fit tool and can carry the script and the HTML contents knot to the server to put together. Chien but speech, apply the complexity of the procedure along with the Web to promote continuously, the development method that take page as the center limits sex to become to get up obviously.At the same time, the people always at look for the better method of build up the Web application procedure, the module spreads in customer's machine/ server the realm. JavaBeans and ActiveX were published the company to expand to apply the procedure developer for Java and Windows to use to come to develop the complicated procedure quickly by" the fast application procedure development"( RAD) tool. These techniques make the expert in the some realm be able to write the module for the perpendicular application plait in the skill area, but the developer can go fetch the usage directly but need not control the expertise of this realm.Be a kind of take module as the central development terrace, the JSP appeared. It with the JavaBeans and Enterprise JavaBeans( EJB) module includes the model of the business and the data logic for foundation, provide a great deal of label and a script terraces to use to come to show in the HTML page from the contents of JavaBeans creation or send a present in return. Because of the property that regards the module as the center of the JSP, it can drive Java and not the developer of Java uses equally. Not the developer of Java can pass the JSP label( Tags) to use the JavaBeans that the deluxe developer of Java establish. The developer of Java not only can establish and use the JavaBeans, but also can use the language of Java to come to control more accurately in the JSP page according to the expression logic of the first floor JavaBeans.See now how JSP is handle claim of HTTP. In basic claim model, a claim directly was send to JSP page in. The code of JSP controls to carry on hour of the logic processing and module of JavaBeanses' hand over with each other, and the manifestation result in dynamic state bornly, mixing with the HTML page of the staticstate HTML code. The Beans can be JavaBeans or module of EJBs. Moreover, the more complicated claim model can see make from is request other JSP pages of the page call sign or Java Servlets.The engine of JSP wants to chase the code of Java that the label of JSP, code of Java in the JSP page even all converts into the big piece together with the static state HTML contents actually. These codes piece was organized the Java Servlet that customer can not see to go to by the engine of JSP, then the Servlet edits and translate them automatically byte code of Java.Thus, the visitant that is the website requests a JSP page, under the condition of it is not knowing, an already born, the Servlet actual full general that prepared to edit and translate completes all works, very concealment but again and efficiently. The Servlet is to edit and translate of, so the code of JSP in the web page does not need when the every time requests that page is explain. The engine of JSP need to be edit and translate after Servlet the code end is modify only once, then this Servlet that editted and translate can be carry out. The in view of the fact JSP engine auto is born to edit and translate the Servlet also, need not procedure member begins to edit and translate the code, so the JSP can bring vivid sex that function and fast developments need that you are efficiently.Compared with the traditional CGI, the JSP has the equal advantage. First, on the speed, the traditional procedure of CGI needs to use the standard importation of the system to output the equipments to carry out the dynamic state web page born, but the JSP is direct is mutually the connection with server. And say for the CGI, each interview needs to add to add a progress to handle, the progress build up and destroy by burning constantly and will be a not small burden for calculator of be the server of Web. The next in order, the JSP is specialized to develop but design for the Web of, its purpose is for building up according to the Web applied procedure, included the norm and the tool of a the whole set. Use the technique of JSP can combine a lot of JSP pages to become a Web application procedure very expediently.1.2 A Servlet's JobServlets are Java programs that run on Web or application servers, acting as a middle layer between requests coming from Web browsers or other HTTP clients and databases or applications on the HTTP server. Their job is to perform the following tasks, as illustrated in Figure 1-1.Figure 1-11．Read the explicit data sent by the client.The end user normally enters this data in an HTML form on a Web page. However, the data could also come from an applet or a custom HTTP client program.2．Read the implicit HTTP request data sent by the browser.Figure 1-1 shows a single arrow going from the client to the Web server (the layer where servlets and JSP execute), but there are really two varieties of data: the explicit data that the end user enters in a form and the behind-the-scenes HTTP information. Both varieties are critical. The HTTP information includes cookies, information about media types and compression schemes the browser understands, and so on. 3．Generate the results.This process may require talking to a database, executing an RMI or EJB call, invoking a Web service, or computing the response directly. Your real data may be in a relational database. Fine. But your database probably doesn't speak HTTP or return results in HTML, so the Web browser can't talk directly to the database. Even if it could, for security reasons, you probably would not want it to. The same argument applies to most other applications. You need the Web middle layer to extract the incoming data from the HTTP stream, talk to the application, and embed the results inside a document.4．Send the explicit data (i.e., the document) to the client.This document can be sent in a variety of formats, including text (HTML or XML), binary (GIF images), or even a compressed format like gzip that is layered on top of some other underlying format. But, HTML is by far the most common format, so an important servlet/JSP task is to wrap the results inside of HTML.5．Send the implicit HTTP response data.Figure 1-1 shows a single arrow going from the Web middle layer (the servlet or JSP page) to the client. But, there are really two varieties of data sent: the document itself and the behind-the-scenes HTTP information. Again, both varieties are critical to effective development. Sending HTTP response data involves telling the browser or other client what type of document is being returned (e.g., HTML), setting cookies and caching parameters, and other such tasks.1.3 Why Build Web Pages Dynamically?many client requests can be satisfied by prebuilt documents, and the server would handle these requests without invoking servlets. In many cases, however, a static result is not sufficient, and a page needs to be generated for each request. There are a number of reasons why Web pages need to be built on-the-fly:1．The Web page is based on data sent by the client.For instance, the results page from search engines and order-confirmation pages at online stores are specific to particular user requests. You don't know what to display until you read the data that the user submits. Just remember that the user submits two kinds of data: explicit (i.e., HTML form data) and implicit (i.e., HTTP request headers). Either kind of input can be used to build the output page. In particular, it is quite common to build a user-specific page based on a cookie value.2．The Web page is derived from data that changes frequently.If the page changes for every request, then you certainly need to build the response at request time. If it changes only periodically, however, you could do it two ways: you could periodically build a new Web page on the server (independently of client requests), or you could wait and only build the page when the user requests it.The right approach depends on the situation, but sometimes it is more convenient to do the latter: wait for the user request. For example, a weather report or news headlines site might build the pages dynamically, perhaps returning a previously built page if that page is still up to date.3．The Web page uses information from corporate databases or other server-side sources.If the information is in a database, you need server-side processing even if the client is using dynamic Web content such as an applet. Imagine using an applet by itself for a search engine site:"Downloading 50 terabyte applet, please wait!" Obviously, that is silly; you need to talk to the database. Going from the client to the Web tier to the database (a three-tier approach) instead of from an applet directly to a database (a two-tier approach) provides increased flexibility and security with little or no performance penalty. After all, the database call is usually the rate-limiting step, so going through the Web server does not slow things down. In fact, a three-tier approach is often faster because the middle tier can perform caching and connection pooling.In principle, servlets are not restricted to Web or application servers that handle HTTP requests but can be used for other types of servers as well. For example, servlets could be embedded in FTP or mail servers to extend their functionality. And, a servlet API for SIP (Session Initiation Protocol) servers was recently standardized (see /en/jsr/detail?id=116). In practice, however, this use of servlets has not caught on, and we'll only be discussing HTTP servlets.1.4 The Advantages of Servlets Over "Traditional" CGIJava servlets are more efficient, easier to use, more powerful, more portable, safer, and cheaper than traditional CGI and many alternative CGI-like technologies. 1．EfficientWith traditional CGI, a new process is started for each HTTP request. If the CGI program itself is relatively short, the overhead of starting the process can dominate theexecution time. With servlets, the Java virtual machine stays running and handles each request with a lightweight Java thread, not a heavyweight operating system process. Similarly, in traditional CGI, if there are N requests to the same CGI program, the code for the CGI program is loaded into memory N times. With servlets, however, there would be N threads, but only a single copy of the servlet class would be loaded. This approach reduces server memory requirements and saves time by instantiating fewer objects. Finally, when a CGI program finishes handling a request, the program terminates. This approach makes it difficult to cache computations, keep database connections open, and perform other optimizations that rely on persistent data. Servlets, however, remain in memory even after they complete a response, so it is straightforward to store arbitrarily complex data between client requests. 2．ConvenientServlets have an extensive infrastructure for automatically parsing and decoding HTML form data, reading and setting HTTP headers, handling cookies, tracking sessions, and many other such high-level utilities. In CGI, you have to do much of this yourself. Besides, if you already know the Java programming language, why learn Perl too? You're already convinced that Java technology makes for more reliable and reusable code than does Visual Basic, VBScript, or C++. Why go back to those languages for server-side programming?3．PowerfulServlets support several capabilities that are difficult or impossible to accomplish with regular CGI. Servlets can talk directly to the Web server, whereas regular CGI programs cannot, at least not without using a server-specific API. Communicating with the Web server makes it easier to translate relative URLs into concrete path names, for instance. Multiple servlets can also share data, making it easy to implement database connection pooling and similar resource-sharing optimizations. Servlets can also maintain information from request to request, simplifying techniques like session tracking and caching of previous computations.4．PortableServlets are written in the Java programming language and follow a standard API.Servlets are supported directly or by a plugin on virtually every major Web server. Consequently, servlets written for, say, Macromedia JRun can run virtually unchanged on Apache Tomcat, Microsoft Internet Information Server (with a separate plugin), IBM WebSphere, iPlanet Enterprise Server, Oracle9i AS, or StarNine WebStar. They are part of the Java 2 Platform, Enterprise Edition (J2EE; see /j2ee/), so industry support for servlets is becoming even more pervasive.5．InexpensiveA number of free or very inexpensive Web servers are good for development use or deployment of low- or medium-volume Web sites. Thus, with servlets and JSP you can start with a free or inexpensive server and migrate to more expensive servers with high-performance capabilities or advanced administration utilities only after your project meets initial success. This is in contrast to many of the other CGI alternatives, which require a significant initial investment for the purchase of a proprietary package.Price and portability are somewhat connected. For example, Marty tries to keep track of the countries of readers that send him questions by email. India was near the top of the list, probably #2 behind the U.S. Marty also taught one of his JSP and servlet training courses (see /) in Manila, and there was great interest in servlet and JSP technology there.Now, why are India and the Philippines both so interested? We surmise that the answer is twofold. First, both countries have large pools of well-educated software developers. Second, both countries have (or had, at that time) highly unfavorable currency exchange rates against the U.S. dollar. So, buying a special-purpose Web server from a U.S. company consumed a large part of early project funds.But, with servlets and JSP, they could start with a free server: Apache Tomcat (either standalone, embedded in the regular Apache Web server, or embedded in Microsoft IIS). Once the project starts to become successful, they could move to a server like Caucho Resin that had higher performance and easier administration but that is not free. But none of their servlets or JSP pages have to be rewritten. If theirproject becomes even larger, they might want to move to a distributed (clustered) environment. No problem: they could move to Macromedia JRun Professional, which supports distributed applications (Web farms). Again, none of their servlets or JSP pages have to be rewritten. If the project becomes quite large and complex, they might want to use Enterprise JavaBeans (EJB) to encapsulate their business logic. So, they might switch to BEA WebLogic or Oracle9i AS. Again, none of their servlets or JSP pages have to be rewritten. Finally, if their project becomes even bigger, they might move it off of their Linux box and onto an IBM mainframe running IBM WebSphere. But once again, none of their servlets or JSP pages have to be rewritten.6．SecureOne of the main sources of vulnerabilities in traditional CGI stems from the fact that the programs are often executed by general-purpose operating system shells. So, the CGI programmer must be careful to filter out characters such as backquotes and semicolons that are treated specially by the shell. Implementing this precaution is harder than one might think, and weaknesses stemming from this problem are constantly being uncovered in widely used CGI libraries.A second source of problems is the fact that some CGI programs are processed by languages that do not automatically check array or string bounds. For example, in C and C++ it is perfectly legal to allocate a 100-element array and then write into the 999th "element," which is really some random part of program memory. So, programmers who forget to perform this check open up their system to deliberate or accidental buffer overflow attacks.Servlets suffer from neither of these problems. Even if a servlet executes a system call (e.g., with Runtime.exec or JNI) to invoke a program on the local operating system, it does not use a shell to do so. And, of course, array bounds checking and other memory protection features are a central part of the Java programming language.7．MainstreamThere are a lot of good technologies out there. But if vendors don't support them and developers don't know how to use them, what good are they? Servlet and JSP。
- 1、下载文档前请自行甄别文档内容的完整性，平台不提供额外的编辑、内容补充、找答案等附加服务。
- 2、"仅部分预览"的文档,不可在线预览部分如存在完整性等问题,可反馈申请退款(可完整预览的文档不适用该条件!)。
- 3、如文档侵犯您的权益，请联系客服反馈,我们会尽快为您处理(人工客服工作时间：9:00-18:30)。
JSP技术概述一、JSP的好处二、JSP页面最终会转换成servler。
因而，从根本上，JSP页面能够执行的任何任务都可以用servler来完成。
然而，这种底层的等同性并不意味着servler和JSP页面对于所有的情况都等同适用。
问题不在于技术的能力，而是二者在便利性、生产率和可维护性上的不同。
毕竟，在特定平台上能够用Java编程语言完成的事情，同样可以用汇编语言来完成，但是选择哪种语言依旧十分重要。
和单独使用servler相比，JSP提供下述好处：三、λJSP中HTML的编写与维护更为简单。
JSP中可以使用常规的HTML：没有额外的反斜杠，没有额外的双引号，也没有暗含的Java语法。
四、λ能够使用标准的网站开发工具。
即使对那些对JSP一无所知的HTML工具，我们也可以使用，因为它们会忽略JSP标签（JSP tags）。
五、λ可以对开发团队进行划分。
Java程序员可以致力于动态代码。
Web开发人员可以将经理集中在表示层（presentation layer）上。
对于大型的项目，这种划分极为重要。
依据开发团队的大小，及项目的复杂程度，可以对静态HTML和动态内容进行弱分离（weaker separation）和强分离（stronger separation）。
六、在此，这个讨论并不是让您停止使用servlets，只使用JSP。
几乎所有的项目都会同时用到这两种技术。
针对项目中的某些请求，您可能会在MVC构架下组合使用这两项技术。
我们总是希望用适当的工具完成相对应的工作，仅仅是servlet并不能填满您的工具箱。
二、JSP相对于竞争技术的优势许多年前，Marty受到邀请,参加一个有关软件技术的小型(20个人)研讨会.做在Marty旁边的人是James Gosling--- Java编程语言的发明者。
隔几个位置,是来自华盛顿一家大型软件公司的高级经理。
在讨论过程中,研讨会的主席提出了Jini的议题,这在当时是一项新的Java技术.主席向该经理询问他的想法.他继续说,他们会持续关注这项技术,如果这项技术变得流行起来,他们会遵循公司的“接受并扩充(embrace and extend)”的策略.此时, Gosling随意地插话说“你的意思其实就是不接受且不扩充(disgrace and distend)。
”在此, Gosling的抱怨显示出，他感到这个公司会从其他公司那里拿走技术,用于他们自己的目的.但你猜这次怎么样?这次鞋子穿在了另一只脚上。
Java社团没有发明这一思想----将页面设计成由静态HTML和用特殊标签标记的动态代码混合组成.。
ColdFusion多年前就已经这样做了。
甚至ASP(来自于前述经理所在公司的一项产品)都在JSP出现之前推广了这种方式。
实际上,JSP不只采用了这种通用概念,它甚至使用许多和ASP相同的特殊标签。
因此,问题变成:为什么使用JSP,而不使用其他技术呢?我们的第一反应是我们不是在争论所有的人应该做什么。
其他这些技术中,有一些也很不错,在某些情况下也的确是合情合理的选择.然而,在其他情形中,JSP明显要更好一些。
下面给出几个理由。
与.NET和Active Server Pages (ASP)相比.NET是Microsoft精心设计的一项技术。
是与servlets和JSP 直接竞争的技术。
JSP的优势体现在两个方面。
首先,JSP可以移植到多种操作系统和Web服务器,您不必仅仅局限于部署在Windows 和IIS上尽管核心.NET平台可以在好几种非Windows平台上运行，但ASP这一部分不可以。
您不能期望可以将重要的应用部署到多种服务器和操作系统。
对于某些应用，这种差异没有什么影响。
但有些应用，这种差异却非常重要。
其次，对于某些应用，底层语言的选择至关重要。
例如，尽管.NET的C#语言设计优良，且和Java类似，但熟悉核心C#语法和众多工具库的程序员很少。
此外,许多开发者依旧使用最初版本的ASP。
相对于这个版本,JSP 在动态代码方面拥有明显的优势。
使用JSP,动态部分是用Java编写的,而非VBScript过其他ASP专有的语言,因此JSP更为强劲,更适合于要求组件重用的复杂应用。
当将JSP与之前版本的ColdFusion对比时，您可能会得到相同的结论。
应用JSP，您可以使用Java编写“真正的代码”，不必依赖于特定的服务器产品。
然而，当前版本的ColdFusion满足J2EE服务器的环境，允许开发者容易的混合使用ColdFusion和Servlet/JSP代码。
与PHP相比PHP（“PHP：Hypertext Preprocessor”的递归字母缩写词）是免费的、开放源代码的、HTML嵌入其中的脚本语言，与ASP和JSP都有某种程度的类似。
JSP的一项优势是动态部分用Java编写，而Java已经在联网、数据库访问、分布式对象等方面拥有广泛的API，而PHP需要学习全新的、应用相对广泛的语言。
JSP的第二项优势是，和PHP相比，JSP拥有极为广泛的工具和服务器提供商的支持。
与纯Servlet相比原则上，JSP并没有提供Servlet不能完成的功能。
实际上，JSP文档在后台被自动转换成Servlet。
但是编写（和修改）常规的HTML，要比无数println语句生成HTML要方便得多。
另外，通过将表示与内容分离，可以为不同的人分配不同的任务：网页设计人员使用熟悉的工具构建HTML，要么为Servlet程序员留出空间插入动态内容，要么通过XML标签间接调用动态内容。
这是否表示您只可以学习JSP，将Servlet丢到一边呢？当然不是！由于以下4种原因，JSP开发人员需要了解Servlet：（1）JSP页面会转换成Servlet。
不了解Servlet就无法知道JSP如何工作。
（2）JSP由静态HTML、专用的JSP标签和Java代码组成。
哪种类型的Java代码呢？当然是Servlet代码！如果不了解Servlet编程，那么就无法编写这种代码。
（3）一些任务用Servlet完成比用JSP来完成要好。
JSP擅长生成由大量组织有序的结构化HTML或其他字符数据组成的页面。
Servlet擅长生成二进制数据，构建结构多样的页面，以及执行输出很少或者没有输出的任务（比如重定向）。
（4）有些任务更适合于组合使用Servlet和JSP来完成，而非单独使用Servlet或JSP。
与JavaScript相比JavaScript和Java编程语言完全是两码事，前者一般用于在客户端动态生成HTML，在浏览器载入文档时构建网页的部分内容。
这是一项有用的功能，一般与JSP的功能（只在服务器端运行）并不发生重叠。
和常规HTML页面一样，JSP页面依旧可以包括用于JavaScript的SCRIPT标签。
实际上，JSP甚至能够用来动态生成发送到客户端的JavaScript。
因此，JavaScript不是一项竞争技术，它是一项补充技术。
JavaScript也可以用在服务器端，最因人注意的是SUN ONE（以前的iPlanet）、IIS和BroadVision服务器。
然而，Java更为强大灵活、可靠且可移植。
与WebMacro和Velocity相比JSP决非完美。
许多人都曾指出过JSP中能够改进的功能。
这是一件好事，JSP的优势之一是该规范由许多不同公司组成的社团控制。
因此，在后续版本中，这项技术能够得到协调的改进。
但是，一些组织已经开发出了基于Java的替代技术，试图弥补这些不足。
据我们的判断，这样做是错误的。
使用扩充JSP和Servlet技术的第三方工具，如Apache Structs，是一种很好的思路，只要该工具带来的好处能够补偿工具带来的额外复杂性。
但是，试图使用非标准的工具代替JSP则不理想。
在选择一项技术时，需要权衡许多方面的因素：标准化、可移植性、集成性、行业支持和技术特性。
对于JSP替代技术的争论几乎只是集中在技术特性上，而可移植性、标准化和集成性也十分重要。
例如，Servlet和JSP规范为Web应用定义了一个标准的目录结构，并提供用于部署Web应用的标准文件（.war文件）。
所有JSP兼容的服务器必须支持这些标准。
我们可以建立过滤器作用到任意树木的Servlet和JSP页面上，但不能用于非标准资源。
Web应用安全设置也同样如此。
此外，业界对JSP和Servlet技术的巨大支持使得这两项技术都有了巨大的进步，从而减轻了对JSP的许多批评。
例如，JSP标准标签库和JSP 2.0表达式语言解决了两种最广泛的批评：缺乏良好的迭代结构；不使用显式的Java代码或冗长的jsp:useBean元素难以访问动态结果。
三、对JSP的误解忘记JSP技术是服务器端技术下面是Marty收到的一些典型问题（大部分问题不止一次的出现）。
λ我们的服务器正在运行JDK1.4。
我如何将Swing组件用到JSP页面中呢？我如何将图像放到JSP页面中？我不知道读取图像文件应该使用哪些Javaλ I/O命令。
Tomcat不支持JavaScript，当用户在图像上移动鼠标时，我如何使图像突出显示呢？λλ我们的客户使用不理解JSP的旧浏览器。
我应该怎么做？当我们的客户在浏览器中使用“Vi ewλSource”（查看源代码）时，如何阻止他们看到JSP标签？所有这些问题都基于浏览器对服务器端的过程在有所了解的假定之上。
但事实上浏览器并不了解服务器端的过程。
因此：λ如果要将使用Swing组件的applet放到网页中，重要的是浏览器的Java版本，和服务器的Java版本无关。
如果浏览器支持Java 2平台，您可以使用正常的APPLET（或Java插件）标签，即使在服务器上使用了非Java技术也须如此。
您不需要JavaλI/O来读取图像文件，您只需将图像放在存储Web资源的目录中（即WEB-INF/classes向上两级的目录），并输出一个正常的IMG标签。
λ您应该用SCRIPT标签，使用客户端JavaScript创建在鼠标下会更改的图像，这不会由于服务器使用JSP而改变。
λ浏览器根本不“支持”JSP----它们看到的只是JSP页面的输出。
因此，如同对待静态HTML页面一样，只需确保JSP输出的HTML与浏览器兼容。
λ当然，您不需要采取什么措施来阻止客户看到JSP标签，这些标签在服务器上进行处理，发送给客户的输出中并不出现。
混淆转换期间和请求期间JSP页面需要转换成servlet。
Servlet在编译后，载入到服务器的内容中，初始化并执行。
但是每一步发生在什么时候呢？要回答这个问题，要记住以下两点：λJSP页面仅在修改后第一次被访问时，才会被转换成servlet并进行编译；λ载入到内存中、初始化和执行遵循servlet的一般规则。