JSP外文文献原稿和译

外文文献原稿和译文
原稿
JSP
JSP (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 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 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.
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.
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 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.
Versus JavaScript
JavaScript, 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 object
1. 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 target
1. 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 targets
out as a target output flow, used to client output data. out targets for the output data.
SIX. Cookie
1. 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.
译文
JSP
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技术有点类似ASP技术，它是在传统的网页HTML 文件(*.htm,*.html)中插入Java程序段(Scriptlet)和JSP标记(tag)，从而形成JSP 文件(*.jsp)。

用JSP开发的Web应用是跨平台的，即能在Linux下运行，也能在其他操作系统上运行。

JSP技术使用Java编程语言编写类XML的tags和scriptlets，来封装产生动态网页的处理逻辑。

网页还能通过tags和scriptlets访问存在于服务端的资源的应用逻辑。

JSP将网页逻辑与网页设计和显示分离，支持可重用的基于组件的设计，使基于Web的应用程序的开发变得迅速和容易。

Web服务器在遇到访问JSP网页的请求时，首先执行其中的程序段，然后将执行结果连同JSP文件中的HTML代码一起返回给客户。

插入的Java程序段可以操作数据库、重新定向网页等，以实现建立动态网页所需要的功能。

JSP与Java Servlet一样，是在服务器端执行的，通常返回该客户端的就是一个HTML文本，因此客户端只要有浏览器就能浏览。

JSP页面由HTML代码和嵌入其中的Java代码所组成。

服务器在页面被客户端请求以后对这些Java代码进行处理，然后将生成的HTML页面返回给客户端的浏览器。

Java Servlet 是JSP的技术基础，而且大型的Web应用程序的开发需要Java Servlet 和JSP配合才能完成。

JSP具备了Java技术的简单易用，完全的面向对象，具有平台无关性且安全可靠，主要面向因特网的所有特点。

JavaScript，这是完全不同于Java的编程语言,通常用于在客户机上动态生成HTML,构建部分的Web页面作为浏览器加载文档。

这是一个有用的功能，并且通常与JSP(仅运行在服务器上)的功能不重叠。

JSP页面还包括对JavaScript脚本标签处理,就像正常的HTML页面做的。

事实上，JSP甚至可以被用来动态地生成JavaScript，将被发送到客户端。

因此，JavaScript并不是一个竞争的技术，它是互补的。

还可以使用JavaScript在服务器上，最显著的是在sun一(原iPlanet)，IIS,BroadVision 服务器。

并且，Java将更强大、灵活、可靠、轻便。

JSP(递归缩写“JSP:超文本预处理器”)是一个免费的、开源的、html嵌入式脚本语言，有点类似于ASP。

JSP动态的部分是用Java编写的,它已经有了一个广泛的API，用于网络、数据库访问、分布式对象,等等,而PHP需要学习一种全新的,更少的
广泛使用的语言。

第二个好处是, 与纯servlet相比，JSP是更广泛的支持，工具和服务器供应商。

JSP提供任何原则上servlet可完成的功能。

事实上，在幕后JSP文件会自动翻译成servlet。

但是它更方便的写(和修改!)普通HTML比使用一个庞大的数字println 语句来生成HTML。

另外,通过将表示从内容，你可以把不同的人分配在不同的任务:你的网页设计专家可以构建HTML通过使用熟悉的工具，你的servlet程序员间接通过XML标签插入动态内容或调用动态内容。

JSP技术的强势
(1)一次编写，到处运行。

在这一点上Java比PHP更出色，除了系统之外，代码不用做任何更改。

(2)系统的多平台支持。

基本上可以在所有平台上的任意环境中开发，在任意环境中进行系统部署，在任意环境中扩展。

相比ASP/PHP的局限性是显而易见的。

(3)强大的可伸缩性。

从只有一个小的Jar文件就可以运行Servlet/JSP，到由多台服务器进行集群和负载均衡，到多台Application进行事务处理，消息处理，一台服务器到无数台服务器，Java显示了一个巨大的生命力。

(4)多样化和功能强大的开发工具支持。

这一点与ASP很像，Java已经有了许多非常优秀的开发工具，而且许多可以免费得到，并且其中许多已经可以顺利的运行于多种平台之下。

JSP技术的弱势：
(1)与ASP一样，Java的一些优势正是它致命的问题所在。

正是由于为了跨平台的功能，为了极度的伸缩能力，所以极大的增加了产品的复杂性。

(2) Java的运行速度是用class常驻内存来完成的，所以它在一些情况下所使用的内存比起用户数量来说确实是“最低性能价格比”了。

从另一方面，它还需要硬盘空间来储存一系列的.java文件和.class文件，以及对应的版本文件。

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。

JSP绝不是完美的。

许多人指出，可以改进。

这是一件好事，优点之一是,该规范是JSP由社区，吸引了来自许多不同的公司。

因此，这种技术可以将改善连续版本。

然而，一些组织已经开发出替代基于java技术来试图解决这些缺陷。

这一点,在我们的判断，是一个错误。

使用第三方工具像Apache Struts，增强JSP和servlet技术是一个好主意当工具添加足够的好处来弥补额外的复杂性。

但是使用一个非标准的工具，试图取代JSP是一个坏主意。

当选择一个技术，你需要权衡许多因素:标准化、可移植性、集成、行业的支持，和技术特点。

对于JSP的参数选择已经几乎只关注技术特征的部分。

但可移植性、标准化和集成也很重要。

例如,servlet和JSP规范定义一个标准为Web应用程序的目录结构,并提供标准的文件(.war文件部署Web应用程序)。

所有jsp兼容的服务器必须支持这些标准。

过滤器可以设置适用于任意数量的servlet或JSP页面,但不非标准的资源。

同样适用于Web应用程序的安全设置。

JSP六种内置对象：
Request，response，out，session，application，config，pagecontext，page，exception。

一. request对象：
该对象封装了用户提交的信息，通过调用该对象相应的方法可以获取封装的信息，即使用该对象可以获取用户提交信息。

二. response对象：
对客户的请求做出动态的响应，向客户端发送数据。

三. session对象
1. 什么是session：session对象是一个JSP内置对象，它在第一个JSP页面被装载时自动创建，完成会话期管理。

从一个客户打开浏览器并连接到服务器开始，到客户关闭浏览器离开这个服务器结束，被称为一个会话。

当一个客户访问一个服务器时，可能会在这个服务器的几个页面之间反复连接，反复刷新一个页面，服务器应当通过某种办法知道这是同一个客户，这就需要session对象。

2. session对象的ID：当一个客户首次访问服务器上的一个JSP页面时，JSP 引擎产生一个session对象，同时分配一个String类型的ID号，JSP引擎同时将这个ID号发送到客户端，存放在Cookie中，这样session对象和客户之间就建立了一一对应的关系。

当客户再访问连接该服务器的其他页面时，不再分配给客户新的session对象，直到客户关闭浏览器后，服务器端该客户的session对象才取消，并且和客户的会话对应关系消失。

当客户重新打开浏览器再连接到该服务器时，服务器为该客户再创建一个新的session对象。

四. aplication对象
1. 什么是application:
服务器启动后就产生了这个application对象，当客户再所访问的网站的各个页面之间浏览时，这个application对象都是同一个，直到服务器关闭。

但是与session 不同的是，所有客户的application对象都是同一个，即所有客户共享这个内置的application对象。

2. application对象常用方法:
(1) public void setAttribute(String key，Object obj)：将参数Object指定的对象obj添加到application对象中，并为添加的对象指定一个索引关键字。

(2) public Object getAttribute(String key)：获取application对象中含有关键字的对象。

五. out对象
out对象是一个输出流，用来向客户端输出数据。

out对象用于各种数据的输出。

六. Cookie
1. 什么是Cookie：
Cookie是Web服务器保存在用户硬盘上的一段文本。

Cookie允许一个Web站点在用户的电脑上保存信息并且随后再取回它。

举例来说，一个Web站点可能会为每一个访问者产生一个唯一的ID，然后以Cookie文件的形式保存在每个用户的机器上。

如果您使用IE浏览器访问Web，您会看到所有保存在您的硬盘上的Cookie。

它们最常存放的地方是：c:\windows\cookies(在Window2000中则是C:\Documents and Settings\您的用户名\Cookies )Cookie是以“关键字key=值value“的格式来保存纪录的.
2. 创建一个Cookie对象，调用Cookie对象的构造函数可以创建Cookie。

Cookie 对象的构造函数有两个字符串参数：Cookie名字和Cookie值。

Cookie c=new Cookie(“username”,”john”);
3. JSP中如果要将封装好的Cookie对象传送到客户端，使用response的addCookie()方法。

格式：response.addCookie(c)
4. 读取保存到客户端的Cookie,使用request对象的getCookies()方法，执行时将所有客户端传来的Cookie对象以数组的形式排列，如果要取出符合需要的Cookie对象，就需要循环比较数组内每个对象的关键字。