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Java编程语言外文翻译、英汉互译、中英对照

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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Java(programming language)Java is a general-purpose, concurrent, class-based, object-oriented computer program- -ming language that is specifically designed to have as few implementation dependencies as possible. It is intended to let application developers "write once, run anywhere" (WORA), meaning that code that runs on one platform does not need to be recompiled to run on another. Java applications are typically compiled to byte code (class file) that can run on any Java virtual machine(JVM) regardless of computer architecture. Java is, as of 2012, one of the most popular programming languages in use, particularly for client-server web applications, with a reported 10 million users. Java was originally developed by James Gosling at Sun Microsystems (which has since merged into Oracle Corporation) and released in 1995 as a core component of Sun Microsystems' Java platform. The language derives much of its syntax from C and C++, but it has fewer low-level facilities than either of them.The original and reference implementation Java compilers, virtual machines, and class libraries were developed by Sun from 1991 and first released in 1995. As of May 2007, in compliance with the specifications of the Java Community Process, Sun relicensed most of its Java technologies under the GNU General Public License. Others have also developed alternative implementations of these Sun technologies, such as the GNU Compiler for Java and GNU Classpath.Java is a set of several computer software products and specifications from Sun Microsystems (which has since merged with Oracle Corporation), that together provide a system for developing application software and deploying it in across-platform computing environment. Java is used in a wide variety of computing platforms from embedded devices and mobile phones on the low end, to enterprise servers and supercomputers on the high end. While less common, Java appletsare sometimes used to provide improved and secure functions while browsing the World Wide Web on desktop computers.Writing in the Java programming language is the primary way to produce code that will be deployed as Java bytecode. There are, however, byte code compilers available forother languages such as Ada, JavaScript, Python, and Ruby. Several new languages have been designed to run natively on the Java Virtual Machine (JVM), such as Scala, Clojure and Groovy.Java syntax borrows heavily from C and C++, but object-oriented features are modeled after Smalltalk and Objective-C. Java eliminates certain low-level constructs such as pointers and has a very simple memory model where every object is allocated on the heap and all variables of object types are references. Memory management is handled through integrated automatic garbage collection performed by the JVM.An edition of the Java platform is the name for a bundle of related programs from Sun that allow for developing and running programs written in the Java programming language. The platform is not specific to any one processor or operating system, but rather an execution engine (called a virtual machine) and a compiler with a set of libraries that are implemented for various hardware and operating systems so that Java programs can run identically on all of them. The Java platform consists of several programs, each of which provides a portion of its overall capabilities. For example, the Java compiler, which converts Java source code into Java byte code (an intermediate language for the JVM), is provided as part of the Java Development Kit (JDK). The Java Runtime Environment(JRE), complementing the JVM with a just-in-time (JIT) compiler, converts intermediate byte code into native machine code on the fly. An extensive set of libraries are also part of the Java platform.The essential components in the platform are the Java language compiler, the libraries, and the runtime environment in which Java intermediate byte code "executes" according to the rules laid out in the virtual machine specification.In most modern operating systems (OSs), a large body of reusable code is provided to simplify the programmer's job. This code is typically provided as a set of dynamically loadable libraries that applications can call at runtime. Because the Java platform is not dependent on any specific operating system, applications cannot rely on any of the pre-existing OS libraries. Instead, the Java platform provides a comprehensive set of its own standard class libraries containing much of the same reusable functions commonly found in modern operating systems. Most of the system library is also written in Java. For instance, Swing library paints the user interface and handles the events itself, eliminatingmany subtle differences between how different platforms handle even similar components.The Java class libraries serve three purposes within the Java platform. First, like other standard code libraries, the Java libraries provide the programmer a well-known set of functions to perform common tasks, such as maintaining lists of items or performing complex string parsing. Second, the class libraries provide an abstract interface to tasks that would normally depend heavily on the hardware and operating system. Tasks such as network access and file access are often heavily intertwined with the distinctive implementations of each platform. The and java.io libraries implement an abstraction layer in native OS code, then provide a standard interface for the Java applications to perform those tasks. Finally, when some underlying platform does not support all of the features a Java application expects, the class libraries work to gracefully handle the absent components, either by emulation to provide a substitute, or at least by providing a consistent way to check for the presence of a specific feature.The success of Java and its write once, run anywhere concept has led to other similar efforts, notably the .NET Framework, appearing since 2002, which incorporates many of the successful aspects of Java. .NET in its complete form (Microsoft's implementation) is currently only fully available on Windows platforms, whereas Java is fully available on many platforms. .NET was built from the ground-up to support multiple programming languages, while the Java platform was initially built to support only the Java language, although many other languages have been made for JVM since..NET includes a Java-like language called Visual J# (formerly named J++) that is incompatible with the Java specification, and the associated class library mostly dates to the old JDK 1.1 version of the language. For these reasons, it is more a transitional language to switch from Java to the .NET platform, than a first class .NET language. Visual J# was discontinued with the release of Microsoft Visual Studio 2008. The existing version shipping with Visual Studio 2005will be supported until 2015 as per the product life-cycle strategy.In June and July 1994, after three days of brainstorming with John Gage, the Director of Science for Sun, Gosling, Joy, Naughton, Wayne Rosing, and Eric Schmidt, the team re-targeted the platform for the World Wide Web. They felt that with the advent of graphical web browsers like Mosaic, the Internet was on its way to evolving into the samehighly interactive medium that they had envisioned for cable TV. As a prototype, Naughton wrote a small browser, Web Runner (named after the movie Blade Runner), later renamed Hot Java.That year, the language was renamed Java after a trademark search revealed that Oak was used by Oak Technology. Although Java 1.0a was available for download in 1994, the first public release of Java was 1.0a2 with the Hot Java browser on May 23, 1995, announced by Gage at the Sun World conference. His announcement was accompanied by a surprise announcement by Marc Andreessen, Executive Vice President of Netscape Communications Corporation, that Netscape browsers would be including Java support. On January 9, 1996, the Java Soft group was formed by Sun Microsystems to develop the technology.Java编程语言Java是一种通用的，并发的，基于类的并且是面向对象的计算机编程语言，它是为实现尽可能地减少执行的依赖关系而特别设计的。

java英文参考文献

三一文库（）〔java英文参考文献〕*篇一：外文参考文献译文及原文本科毕业设计（论文）外文参考文献译文及原文学院_____计算机学院______专业___计算机科学与技术___年级班别____2009级（1）班__学号学生姓名_______________指导教师______________2013年5月目录译文：C#.NET开发者指南前言................................................. ................................................... . (1)第一章微软.NET平台的介绍................................................. (3)1.1简介................................................. ................................................... . (3)平台简介................................................. .. (3)1.1.2微软的.NET和WINDOWS的基因................................................. . (4)1.1.3微软.NET体系结构................................................. (4)平台的特点................................................. . (4)1.1.5多国语言的发展................................................. .. (5)1.1.6平台和处理器独立性................................................. .. (6)1.1.7自动内存管理................................................. (7)1.1.8支持的版本................................................. ................................................... ..71.1.9支持的开放标准................................................. .. (8)1.1.10配置简单................................................. ................................................... . (8)1.1.11分布式体系结构................................................. (9)1.1.12与非托管代码的互用................................................. (9)原文：C#.NETWebDevelopersGuideForeword........................................... ................................................... ........................................11Chapter1I Platform.............. .. (13)1.1Introduction.................................... ................................................... (13)Platform................. . (13)andWindowsDNA.................... . (15)ArchitectureHierarchy............ (15)Platform..................... (16)1.1.5MultilanguageDevelopment...................... .. (17)1.1.6PlatformandProcessorIndependence.............. .. (18)1.1.7AutomaticMemoryManagement..................... . (19)1.1.8VersioningSupport............................. ................................................... ..201.1.9SupportforOpenStandards....................... .. (21)1.1.10EasyDeployment............................... ................................................... . (22)1.1.11DistributedArchitecture...................... .. (23)1.1.12InteroperabilitywithUnmanagedCode............ (23)译文：C#.NET开发者指南前言在电脑软件的历史上，很少有一种技术能够得到开发者和业界如此强烈的正面响应。

关于java英文参考文献

关于java英文参考文献Java, a versatile programming language, has been a cornerstone of software development since its inception in the mid-1990s. Its object-oriented nature and platform independence make it a popular choice for developers worldwide.The language's extensive ecosystem is well-documented in numerous scholarly articles and books, offering insights into its design principles and practical applications. For beginners, "Head First Java" by Kathy Sierra and Bert Batesis a recommended starting point, blending engaging narratives with technical explanations.As one progresses, "Effective Java" by Joshua Bloch provides a more in-depth look at the language's best practices, catering to intermediate and advanced programmers. It covers topics such as exception handling and concurrency, which are crucial for writing robust Java applications.For a comprehensive understanding of Java's underlying mechanisms, "Java Concurrency in Practice" by Brian Goetz et al. is an invaluable resource. It delves into the complexities of multi-threading, a critical aspect of modern software development.When exploring Java's integration with web technologies, "Java Web Services" by William C. Crawford provides a clearguide to building and consuming web services, a common requirement in today's interconnected applications.Lastly, for those interested in the broader implications of Java in enterprise environments, "Enterprise Integration Patterns" by Gregor Hohpe and Bobby Woolf offers a collection of design patterns that facilitate the building ofdistributed systems.These references not only serve as educational tools but also as a testament to the enduring influence of Java in the field of computer science.。

java JDBC 外文翻译外文文献英文文献

java JDBC 外文翻译外文文献英文文献原文一:Java Programming with Oracle JDBC:PerformancePerformance is usually considered an issue at the end of a development cycle when it should really be considered from thestart.Often, a task called "performance tuning" is done after the coding is complete, and the end user of a program complains about how long it takes the program to complete a particular task.The net result of waiting until the end of the development cycle to consider performance includes the expense of the additional time required to recode a program to improve its performance.It's my opinion that performance is something that is best considered at the start of a project.When it comes to performance issues concerning JDBC programmingthere are two major factors to consider. The first is the performance of the database structure and the SQL statements used against it. The second is the relative efficiency of the different ways you can use the JDBC interfaces to manipulate a database.In terms of the database's efficiency, you can use the EXPLAIN PLAN facility to explain how the database's optimizer plans to execute your SQL statements. Armed with this knowledge, you may determine that additional indexes are needed, or that you require an alternative means of selecting the data you desire.On the other hand, when it comes to using JDBC, you need to know ahead of time the relative strengths and weaknesses of using auto-commit, SQL92 syntax, and a Statement versus a PreparedStatement versus a CallableStatement object. In this chapter, we'll examine the relative performance of various JDBC objects using example programs that report the amount of time it takes to accomplish a given task. We'll first look at auto-commit. Next, we'll look at the impact of the SQL92 syntax parser. Then we'll start a series of comparisons of the Statement object versus the PreparedStatement object versus the CallableStatement object. At the same time we'll also examine the performance of the OCI versusthe Thin driver in each situation to see if, as Oracle's claims, thereis a significant enough performance gain with the OCI driver that you should use it instead of the Thin driver. For the most part, our discussions will be based on timing data for 1,000 inserts into the test performance table TESTXXXPERF. There are separate programs forperforming these 1,000 inserts using the OCI driver and the Thin driver.The performance test programs themselves are very simple and are available online with the rest of the examples in this book. However,for brevity, I'll not show the code for the examples in this chapter.I'll only talk about them. Although the actual timing values change from system to system, their relative values, or ratios from one system to another, remain consistent. The timings used in this chapter were gathered using Windows 2000. Using objective data fromthese programs allows us to come to factual conclusions on which factors improve performance, rather than relying on hearsay.I'm sure you'll be surprised at the reality of performance for these objects, and I hope you'll use this knowledge to your advantage. Let's get started with a look at the testing framework used in this chapter.A Testing FrameworkFor the most part, the test programs in this chapter report the timings for inserting data into a table. I picked an INSERT statement because it eliminates the performance gain of the database block buffers that may skew timings for an UPDATE, DELETE, or SELECT .The test table used in the example programs in this chapter is a simple relational table. I wanted it to have a NUMBER, a small VARCHAR2, a large VARCHAR2, and a DATE column. Table TESTXXXPERF is defined as:create table TestXXXPerf (id number,code varchar2(30),descr varchar2(80),insert_user varchar2(30),insert_date date )tablespace users pctfree 20storage( initial 1 M next 1 M pctincrease 0 );alter table TestXXXPerfadd constraint TestXXXPerf_Pkprimary key ( id )using indextablespace users pctfree 20storage( initial 1 M next 1 M pctincrease 0 );The initial extent size used for the table makes it unlikely thatthe database will need to take the time to allocate another extentduring the execution of one of the test programs. Therefore, extent allocation will not impact the timings. Given this background, youshould have a context to understand what is done in each section by each test program. Auto-CommitBy default, JDBC's auto-commit feature is on, which means that each SQL statement is committed as it is executed. If more than one SQL statement is executed by yourprogram, then a small performance increase can be achieved byturning off auto-commit.Let's take a look at some numbers. Table 19-1 shows the average time, in milliseconds, needed to insert 1,000 rows into the TESTXXXPERF table using a Statement object. The timings represent the average from three runs of the program. Both drivers experience approximately a one-second loss as overhead for committing between each SQL statement. When you divide that one second by 1,000 inserts, you can see that turning off auto-commit saves approximately 0.001 seconds (1 millisecond) per SQL statement. While that's not interesting enough to write home about, it does demonstrate how auto-commit can impact performance.Table 19-1: Auto-commit timings (in milliseconds)Auto-commit OCI ThinOn 3,712 3,675Off 2,613 2,594Clearly, it's more important to turn off auto-commit for managing multistep transactions than for gaining performance. But on a heavily loaded system where many users are committing transactions, the amountof time it takes to perform commits can become quite significant. So my recommendation is to turn off auto-commit and manage your transactions manually. The rest of the tests in this chapter are performed with auto-commit turned off.SQL92 Token ParsingLike auto-commit, SQL92 escape syntax token parsing is on by default. In case you don't recall, SQL92 token parsing allows you to embed SQL92 escape syntax in your SQL statements (see "Oracle and SQL92 Escape Syntax" in Chapter 9). These standards-based snippets of syntax are parsed by a JDBC driver transforming the SQL statement into its native syntax for the target database. SQL92 escape syntax allows you to make your code more portable--but does this portability come with a cost in terms of performance?Table 19-2 shows the number of milliseconds needed to insert 1,000 rows into the TESTXXXPERF table. Timings are shown with the SQL92 escape syntax parser on and off for both the OCI and Thin drivers. As before, these timings represent the result of three program runs averaged together.Table 19-2: SQL92 token parser timings (in milliseconds)SQL92 parser OCI ThinOn 2,567 2,514Off 2,744 2,550Notice from Table 19-2 that with the OCI driver we lose 177 milliseconds when escape syntax parsing is turned off, and we lose only 37 milliseconds when the parser is turned off with the Thin driver. These results are the opposite of what you might intuitively expect. It appears that both drivers have been optimized for SQL92 parsing, so you should leave it on for best performance.Now that you know you never have to worry about turning the SQL92 parser off, let's move on to something that has some potential for providing a substantial performance improvement.Statement Versus PreparedStatementThere's a popular belief that using a PreparedStatement object is faster than using a Statement object. After all, a prepared statement has to verify its metadata against the database only once, while a statement has to do it every time. So how could it be any other way? Well, the truth of the matter is that it takes about 65 iterations of a prepared statement before its total time for execution catches up with a statement. When it comes to which SQL statement object performs better under typical use, a Statement or aPreparedStatement, the truth is that the Statement object yields the best performance. When you consider how SQL statements are typicallyused in an application--1 or 2 here, maybe 10-20 (rarely more) per transaction--you realize that a Statement object will perform them in less time than a PreparedStatement object. In the next two sections,we'll look at this performance issue with respect to both the OCI driver and the Thin driver. The OCI DriverTable 19-3 shows the timings in milliseconds for 1 insert and 1,000 inserts in the TESTXXXPERF table. The inserts are done first using a Statement object and then a PreparedStatement object. If you look at the results for 1,000 inserts, you may think that a prepared statement performs better. After all, at 1,000 inserts, the PreparedStatement object is almost twice as fast as the Statement object, but if you examine Figure 19-1, you'll see a different story.Table 19-3: OCI driver timings (in milliseconds)Inserts Statement PreparedStatement1 10 1131,000 2,804 1,412Figure 19-1 is a graph of the timings needed to insert varying numbers of rows using both a Statement object and a PreparedStatement object. The number of inserts begins at 1 and climbs in intervals of 10 up to a maximum of 150 inserts. For this graph and for those that follow, the lines themselves are polynomial trend lines with a factor of 2. I chose polynomial lines instead of straight trend lines so you can better see a change in the performance as the number of inserts increases. I chose a factor of 2 so the lines have only one curve inthem. The important thing to notice about the graph is that it's not until about 65 inserts that the PreparedStatement object outperforms the Statement object. 65 inserts! Clearly, the Statement object is more efficient under typical use when using the OCI driver.Figure 19-1The Thin DriverIf you examine Table 19-4 (which shows the same timings as for Table 19-3, but for the Thin driver) and Figure 19-2 (which shows the data incrementally), you'll see that the Thin driver follows the same behavior as the OCI driver. However, since the Statement object starts out performing better than the PreparedStatement object, it takes about 125 inserts for the PreparedStatement to outperform Statement.Table 19-4: Thin driver timings (in milliseconds)Inserts Statement PreparedStatement1 10 1131,000 2,583 1,739Figure 19-2When you consider typical SQL statement usage, even with the Thin driver, you'll get better performance if you execute your SQL statements using a Statement object instead of a PreparedStatement object. Given that, you may ask: why use a PreparedStatement at all? It turns out that there are some reasons why you might use a PreparedStatement object to execute SQL statements. First, there are several types of operationsthat you simply can't perform without PreparedStatement object.For example,you must use a PreparedStatement object if you want to use large objects like BLOBs or CLOBs or if you wish to use object SQL. Essentially, you trade some loss of performance for the added functionality ofusing these object technologies.A second reason to use a PreparedStatement is its support for batching.BatchingAs you saw in the previous section, PreparedStatement objects eventually become more efficient than their Statement counterparts after 65-125 executions of the same statement. If you're going to execute a given SQL statement a large number of times, it makes sense from aperformance standpoint to use a PreparedStatement object. But if you're really going to do that many executions of a statement, or perhaps more than 50, you should consider batching. Batching is more efficient because it sends multiple SQL statements to the server at one time. Although JDBC defines batching capability for Statement objects, Oracle supports batching only when Prepared-Statement objects are used. This makes some sense. A SQL statement in a PreparedStatement object is parsed once and can be reused many times. This naturally lends itself to batching. The OCI DriverTable 19-5 lists Statement and batched PreparedStatement timings, in milliseconds, for 1 insert and for 1,000 inserts. At the low end, one insert, you take a small performance hit for supporting batching. At the high end, 1,000 inserts, you've gained 75% throughput.Table 19-5: OCI driver timings (in milliseconds)Inserts Statement Batched1 10 1171,000 2,804 691If you examine Figure 19-3, a trend line analysis of the Statement object versus the batched PreparedStatement object, you'll see that this time, the batched Prepared-Statement object becomes more efficient than the Statement object at about 50 inserts. This is an improvement over the prepared statement without batching.Figure 19-3WARNING: There's a catch here. The 8.1.6 OCI driver has a defect by which it does not support standard Java batching, so the numbers reported here were derived using Oracle's proprietary batching.Now, let's take a look at batching in conjunction with the Thin driver. The Thin DriverThe Thin driver is even more efficient than the OCI driver when it comes to using batched prepared statements. Table 19-6 shows the timings for the Thin driver using a Statement object versus a batched PreparedStatement object in milliseconds for the specified number of inserts.Table 19-6: Thin driver timings (in milliseconds)Inserts Statement Batched1 10 1171,000 2,583 367The Thin driver takes the same performance hit on the low end, one insert, but gains a whopping 86% improvement on the high end. Yes, 1,000 inserts in less than a second! If you examine Figure 19-4, you'll see that with the Thin driver, the use of a batched PreparedStatement objectbecomes more efficient than a Statement object more quickly than with the OCI driver--at about 40 inserts.Figure 19-4If you intend to perform many iterations of the same SQL statement against a database, you should consider batching with a PreparedStatement object.We've finished looking at improving the performance of inserts, updates, and deletes. Now let's see what we can do to squeak out alittle performance while selecting data. Predefined SELECT Statements Every time you execute a SELECT statement, the JDBC driver makes two round trips to the database. On the first round trip, it retrieves the metadata for the columns you are selecting. On the second round trip, it retrieves the actual data you selected. With this in mind, you can improve the performance of a SELECT statement by 50% if you predefine the Selecstatement by using Oracle's defineColumnType()method with an OracleStatement object (see "Defining Columns" in Chapter 9). When you predefine a SELECT statement, you provide the JDBC driver with the column metadata using the defineColumnType() method, obviating the needfor the driver to make a round trip to the database for that information. Hence, for a singleton SELECT, you eliminate half the work when you predefine the statement.Table 19-7 shows the timings in milliseconds required to select a single row from the TESTXXXPERF table. Timings are shown for when the column type has been predefined and when it has not been predefined. Timings are shown for both the OCI and Thin drivers. Although the defineColumnType() method shows little improvement with either driver in my test, on a loaded network, you'll see a differentiation in thetimings of about 50%. Given a situation in which you need to makeseveral tight calls to the database using a Statement, a predefined SELECT statement can save you a significant amount of time.Table 19-7: Select timings (in milliseconds)Driver Statement defineColumnType( )OCI 13 10Thin 13 10Now that we've looked at auto-commit, SQL92 parsing, prepared statements, and a predefined SELECT, let's take a look at the performance of callable statements. CallableStatementsAs you may recall, CallableStatement objects are used to execute database stored procedures. I've saved CallableStatement objects until last, because they are the slowest performers of all the JDBC SQL execution interfaces. This may sound counterintuitive, because it's commonly believed that calling stored procedures is faster than usingSQL, but that's simply not true. Given a simple SQL statement, and a stored procedure call thataccomplishes the same task, the simple SQL statement will always execute faster. Why? Because with the stored procedure, you not only have the time needed to execute the SQL statement but also the time needed to deal with the overhead of the procedure call itself.Table 19-8 lists the relative time, in milliseconds, needed to call the stored procedure TESTXXXPERF$.SETTESTXXXPERF(). This stored procedure inserts one row into thetable TESTXXXPERF. Timings are provided for both the OCI and Thin drivers. Notice that both drivers are slower when inserting a row this way than when using either a statement or a batched prepared statement (refer to Tables 19-3 through 19-6). Common sense will tell you why. The SETTESTXXXPERF()procedure inserts a row into thedatabase. It does exactly the same thing that the other JDBC objects did but with the added overhead of a round trip for executing the remote procedure call.Table 19-8: Stored procedure call timings (in milliseconds)Inserts OCI Thin1 113 1171,000 1,723 1,752Stored procedures do have their uses. If you have a complex taskthat requires several SQL statements to complete, and you encapsulate those SQL statements into a stored procedure that you then call onlyonce, you'll get better performance than if you executed each SQL statement separately from your program. This performance gain is the result of your program not having to move all the related data back and forth over the network, which is often the slowest part of the data manipulation process. This is how stored procedures are supposed to be used with Oracle--not as a substitute for SQL, but as a means to perform work where it can be done most efficiently.OCI Versus Thin DriversOracle's documentation states that you should use the OCI driver for maximum performance and the Thin driver for maximum portability. However, I recommend using the Thin driver all the time. Let's take a look at some numbers from Windows 2000. Table 19-9 lists all the statisticswe've covered in this chapter.Table 19-9: OCI versus Thin driver timings (in milliseconds)Metric OCI Thin1,000 inserts with auto-commit 3,712 3,6751,000 inserts with manual commit 2,613 2,5941 insert with Statement 10 101,000 inserts with Statement 2,804 2,5831 insert with PreparedStatement 113 1131,000 inserts batched 1,482 367SELECT 10 10Predefined SELECT 10 101 insert with CallableStatement 113 1171,000 inserts with CallableStatement 1,723 1,752Totals 12,590 11,231As you can see from Table 19-9, the Thin driver clearly outperforms the OCI driver for every type of operation except executions of CallableStatement objects. On a Unix platform, my experience has been that the CallableStatement numbers are tilted even more in favor of the OCI driver. Nonetheless, you can feel completely comfortable using the Thin driver in almost any setting. The Thin driver has been well-tuned by Oracle's JDBC development team to perform better than its OCI counterpart.原文二:Extending StrutsIntroductionI have seen lot of projects where the developers implemented a proprietary MVC framework, not because they wanted to do something fundamentally different from Struts, but because they were not aware of how to extend Struts. You can get total control by developing your own MVC framework, but it also means you have to commit a lot of resources to it, something that may not be possible in projects with tight schedules.Struts is not only a very powerful framework, but also very extensible. You can extend Struts in three ways.PlugIn: Create your own PlugIn class if you want to execute some business logic at application startup or shutdown.RequestProcessor: Create your own RequestProcessor if you want to execute some business logic at a particular point during the request-processing phase. For example, you might extend RequestProcessor tocheck that the user is logged in and he has one of the roles to executea particular action before executing every request.ActionServlet: You can extend the ActionServlet class if you want to execute your business logic at either application startup or shutdown,or during request processing. But you should use it only in cases where neither PlugIn nor RequestProcessor is able to fulfill your requirement.In this article, we will use a sample Struts application to demonstrate how to extend Struts using each of these three approaches. Downloadable sample code for each is available below in the Resources section at the end of this article. Two of the most successful examples of Struts extensions are the Struts Validation framework and the Tiles framework.I assume that you are already familiar with the Struts framework and know how to create simple applications using it. Please see the Resources section if you want to know more about Struts.PlugInAccording to the Struts documentation "A plugin is a configuration wrapper for a module-specific resource or service that needs to be notified about application startup and shutdown events." What this means is that you can create a class implementing the PlugIn interface to do something at application startup or shutdown.Say I am creating a web application where I am using Hibernate asthe persistencemechanism, and I want to initialize Hibernate as soon as the application starts up, so that by the time my web application receives the first request, Hibernate is already configured and ready to use. We also want to close down Hibernate when the application is shutting down. We can implement this requirement with a Hibernate PlugIn by following two simple steps.Create a class implementing the PlugIn interface, like this:public class HibernatePlugIn implements PlugIn{private String configFile;// This method will be called at application shutdown timepublic void destroy() {System.out.println("Entering HibernatePlugIn.destroy()");//Put hibernate cleanup code hereSystem.out.println("Exiting HibernatePlugIn.destroy()");}//This method will be called at application startup timepublic void init(ActionServlet actionServlet, ModuleConfig config) throws ServletException {System.out.println("Entering HibernatePlugIn.init()");System.out.println("Value of init parameter " +getConfigFile());System.out.println("Exiting HibernatePlugIn.init()");}public String getConfigFile() {return name;}public void setConfigFile(String string) {configFile = string;}}The class implementing PlugIn interface must implement two methods: init() and destroy(). init() is called when the application starts up, and destroy() is called at shutdown. Struts allows you to pass init parameters to your PlugIn class. For passing parameters, you have to create JavaBean-type setter methods in your PlugIn class for every parameter. In our HibernatePlugIn class, I wanted to pass the name of the configFile instead of hard-coding it in the application.Inform Struts about the new PlugIn by adding these lines to struts-config.xml:<struts-config><message-resources parameter="sample1.resources.ApplicationResources"/><plug-in className="com.sample.util.HibernatePlugIn"><set-property property="configFile"value="/hibernate.cfg.xml"/></plug-in></struts-config>The className attribute is the fully qualified name of the class implementing the PlugIn interface. Add a <set-property> element for every initialization parameter which you want to pass to your PlugIn class. In our example, I wanted to pass the name of the config file, so I added the <set-property> element with the value of config file path.Both the Tiles and Validator frameworks use PlugIns forinitialization by reading configuration files. Two more things which you can do in your PlugIn class are:If your application depends on some configuration files, then youcan check their availability in the PlugIn class and throw a ServletException if the configuration file is not available. This will result in ActionServlet becoming unavailable.The PlugIn interface's init() method is your last chance if you want to change something in ModuleConfig, which is a collection of static configuration information that describes a Struts-based module. Struts will freeze ModuleConfig once all PlugIns are processed.How a Request is ProcessedActionServlet is the only servlet in Struts framework, and is responsible for handling all of the requests. Whenever it receives a request, it first tries to find a sub-application for the current request. Once a sub-application is found, it creates a RequestProcessorobject for that sub-application and calls its process() method bypassing it HttpServletRequest and HttpServletResponse objects.The RequestProcessor.process() is where most of the request processing takes place. The process() method is implemented using the Template Method design pattern, in which there is a separate method for performing each step of request processing, and all of those methods are called in sequence from the process() method. For example, there are separate methods for finding the ActionForm class associated with the current request, and checking if the current user has one of therequired roles to execute action mapping. This gives ustremendous flexibility. The RequestProcessor class in the Struts distribution provides a default implementation for each of the request-processing steps. That means you can override only the methods that interest you, and use default implementations for rest of the methods. For example, by default Struts calls request.isUserInRole() to find out if the user has one of the roles required to execute the current ActionMapping, but if you want to query a database for this, then thenall you have to do is override the processRoles() method and return true or false, based whether the user has the required role or not.First we will see how the process() method is implemented by default, and then I will explain what each method in the default RequestProcessor class does, so that you can decide what parts of request processing you want to change.public void process(HttpServletRequest request,HttpServletResponse response)throws IOException, ServletException {// Wrap multipart requests with a special wrapper request = processMultipart(request);// Identify the path component we will// use to select a mappingString path = processPath(request, response);if (path == null) {return;}if (log.isDebugEnabled()) {log.debug("Processing a '" + request.getMethod() + "' for path '" + path + "'");}// Select a Locale for the current user if requested processLocale(request, response);// Set the content type and no-caching headers// if requestedprocessContent(request, response);processNoCache(request, response);// General purpose preprocessing hookif (!processPreprocess(request, response)) {return;}。

JAVA外文文献+翻译

Java and the InternetIf Java is, in fact, yet another computer programming language, you may question why it is so important and why it is being promoted as a revolutionary step in computer programming. The answer isn’t immediately obvious if you’re coming from a traditional programming perspective. Although Java is very useful for solving traditional stand-alone programming problems, it is also important because it will solve programming problems on the World Wide Web.1.Client-side programmingThe Web’s initial server-browser design provided for interactive content, but the interactivity was completely provided by the server. The server produced static pages for the client browser, which would simply interpret and display them. Basic HTML contains simple mechanisms for data gathering: text-entry boxes, check boxes, radio boxes, lists and drop-down lists, as well as a button that can only be programmed to reset the data on the form or “submit” the data on the form back to the server. This submission passes through the Common Gateway Interface (CGI) provided on all Web servers. The text within the submission tells CGI what to do with it. The most common action is to run a program located on the server in a directory that’s typically called “cgi-bin.” (If you watch the address window at the top of your browser when you push a button on a Web page, you can sometimes see “cgi-bin” within all the gobbledygook there.) These programs can be written in most languages. Perl is acommon choice because it is designed for text manipulation and is interpreted, so it can be installed on any server regardless of processor or operating system. Many powerful Web sites today are built strictly on CGI, and you can in fact do nearly anything with it. However, Web sites built on CGI programs can rapidly become overly complicated to maintain, and there is also the problem of response time. The response of a CGI program depends on how much data must be sent, as well as the load on both the server and the Internet. (On top of this, starting a CGI program tends to be slow.) The initial designers of the Web did not foresee how rapidly this bandwidth would be exhausted for the kinds of applications people developed. For example, any sort of dynamic graphing is nearly impossible to perform with consistency because a GIF file must be created and moved from the server to the client for each version of the graph. And you’ve no doubt had direct experience with something as simple as validating the data on an input form. You press the submit button on a page; the data is shipped back to the server; the server starts a CGI program that discovers an error, formats an HTML page informing you of the error, and then sends the page back to you; you must then back up a page and try again. Not only is this slow, it’s inelegant.The solution is client-side programming. Most machines that run Web browsers are powerful engines capable of doing vast work, and with the original static HTML approach they are sitting there, just idly waiting for the server to dish up the next page. Client-side programming means that the Web browser is harnessed to do whatever work it can, and the result for the user is a much speedier and more interactive experience at your Web site.The problem with discussions of client-side programming is that they aren’t very different from discussions of programming in general. The parameters are almost the same, but the platform is different: a Web browser is like a limited operating system. In the end, you must still program, and this accounts for the dizzying array of problems and solutions produced by client-side programming. The rest of this section provides an overview of the issues and approaches in client-side programming.2.Plug-insOne of the most significant steps forward in client-side programming is the development of the plug-in. This is a way for a programmer to add new functionality to the browser by downloading a piece of code that plugs itself into the appropriate spot in the browser. It tells the browser “from now on you can perform this new activity.” (You ne ed to download the plug-in only once.) Some fast and powerful behavior is added to browsers via plug-ins, but writing a plug-in is not a trivial task, and isn’t something you’d want to do as part of the process of building a particular site. The value of the plug-in for client-side programming is that it allows an expert programmer to develop a new language and add that language to a browser without the permission of the browser manufacturer. Thus, plug-ins provide a “back door” that allows the creation of new client-side programming languages (although not all languages are implemented as plug-ins).3.Scripting languagesPlug-ins resulted in an explosion of scripting languages. With a scripting language you embed the source code for your client-side program directly into the HTML page, and the plug-in that interprets that language is automatically activated while the HTML page is being displayed. Scripting languages tend to be reasonably easy to understand and, because they are simply text that is part of an HTML page, they load very quickly as part of the single server hit required to procure that page. The trade-off is that your code is exposed for everyone to see (and steal). Generally, however, you aren’t doing amazingly sophisticated things with scripting languages so this is not too much of a hardship.This points out that the scripting languages used inside Web browsers are really intended to solve specific types of problems, primarily the creation of richer and more interactive graphical user interfaces (GUIs). However, a scripting language might solve 80 percent of the problems encountered in client-side programming. Your problems might very well fit completely withinthat 80 percent, and since scripting languages can allow easier and faster development, you should probably consider a scripting language before looking at a more involved solution such as Java or ActiveX programming.The most commonly discussed browser scripting languages are JavaScript (which has nothing to do with Java; it’s named that way just to grab some of Java’s marketing momentum), VBScript (which looks like Visual Basic), and Tcl/Tk, which comes from the popular cross-platform GUI-building language. There are others out there, and no doubt more in development.JavaScript is probably the most commonly supported. It comes built into both Netscape Navigator and the Microsoft Internet Explorer (IE). In addition, there are probably more JavaScript books available than there are for the other browser languages, and some tools automatically create pages using JavaScript. However, if you’re already fluent in Visual Basic or Tcl/Tk, you’ll be more productive using those scripting languages rather than learning a new one. (You’ll have your hands full dealing with the Web issues already.)4.JavaIf a scripting language can solve 80 percent of the client-side programming problems, what about the other 20 percent—the “really hard stuff?” The most popular solution today is Java. Not only is it a powerful programming language built to be secure, cross-platform, and international, but Java is being continually extended to provide language features and libraries that elegantly handle problems that are difficult in traditional programming languages, such as multithreading, database access, network programming, and distributed computing. Java allows client-side programming via the applet.An applet is a mini-program that will run only under a Web browser. The applet is downloaded automatically as part of a Web page (just as, for example, a graphic is automatically downloaded). When the applet is activated it executes a program. This is part of its beauty—it provides you with a way to automatically distribute the client software from the server at the time the user needs the client software, and no sooner. The user gets the latest version of the client software without fail and without difficult reinstallation. Because of theway Java is designed, the programmer needs to create only a single program, and that program automatically works with all computers that have browsers with built-in Java interpreters. (This safely includes the vast majority of machines.) Since Java is a full-fledged programming language, you can do as much work as possible on the client before and after making requests of the server. F or example, you won’t need to send a request form across the Internet to discover that you’ve gotten a date or some other parameter wrong, and your client computer can quickly do the work of plotting data instead of waiting for the server to make a plot and ship a graphic image back to you. Not only do you get the immediate win of speed and responsiveness, but the general network traffic and load on servers can be reduced, preventing the entire Internet from slowing down.One advantage a Java applet has ove r a scripted program is that it’s in compiled form, so the source code isn’t available to the client. On the other hand, a Java applet can be decompiled without too much trouble, but hiding your code is often not an important issue. Two other factors can be important. As you will see later in this book, a compiled Java applet can comprise many modules and take multiple server “hits” (accesses) to download. (In Java 1.1 and higher this is minimized by Java archives, called JAR files, that allow all the required modules to be packaged together and compressed for a single download.) A scripted program will just be integrated into the Web page as part of its text (and will generally be smaller and reduce server hits). This could be important to the responsiveness of your Web site. Another factor is the all-important learning curve. Regardless of what you’ve heard, Java is not a trivial language to learn. If you’re a Visual Basic programmer, moving to VBScript will be your fastest solution, and since it will probably solve most typical client/server problems you might be hard pressed to justify learning Java. If you’re experienced with a scripting language you will certainly benefit from looking at JavaScript or VBScript before committing to Java, since they might fit your needs handily and you’ll be more productive sooner.to run its applets withi5.ActiveXTo some degree, the competitor to Java is Microsoft’s ActiveX, although it takes a completely different approach. ActiveX was originally a Windows-only solution, although it is now being developed via an independent consortium to become cross-platform. Effectively, ActiveX says “if your program connects to its environment just so, it can be dropped into a Web page and run under a browser that supports ActiveX.” (I E directly supports ActiveX and Netscape does so using a plug-in.) Thus, ActiveX does not constrain you to a particular language. If, for example, you’re already an experienced Windows programmer using a language such as C++, Visual Basic, or Borland’s Del phi, you can create ActiveX components with almost no changes to your programming knowledge. ActiveX also provides a path for the use of legacy code in your Web pages.6.SecurityAutomatically downloading and running programs across the Internet can sound like a virus-builder’s dream. ActiveX especially brings up the thorny issue of security in client-side programming. If you click on a Web site, you might automatically download any number of things along with the HTML page: GIF files, script code, compiled Java code, and ActiveX components. Some of these are benign; GIF files can’t do any harm, and scripting languages are generally limited in what they can do. Java was also designed to run its applets within a “sandbox” of safety, which prevents it from wri ting to disk or accessing memory outside the sandbox.ActiveX is at the opposite end of the spectrum. Programming with ActiveX is like programming Windows—you can do anything you want. So if you click on a page that downloads an ActiveX component, that component might cause damage to the files on your disk. Of course, programs that you load onto your computer that are not restricted to running inside a Web browser can do the same thing. Viruses downloaded from Bulletin-Board Systems (BBSs) have long been a problem, but the speed of the Internet amplifies the difficulty.The solution seems to be “digital signatures,” whereby code is verified to show who the author is. This is based on the idea that a virus works because its creator can be anonymous, so if you remove the anonymity individuals will be forced to be responsible for their actions. This seems like a good plan because it allows programs to be much more functional, and I suspect it will eliminate malicious mischief. If, however, a program has an unintentional destructive bug it will still cause problems.The Java approach is to prevent these problems from occurring, via the sandbox. The Java interpreter that lives on your local Web browser examines the applet for any untoward instructions as the applet is being loaded. In particular, the applet cannot write files to disk or erase files (one of the mainstays of viruses). Applets are generally considered to be safe, and since this is essential for reliable client/server systems, any bugs in the Java language that allow viruses are rapidly repaired. (It’s worth noting that the browser software actually enforces these security restrictions, and some browsers allow you to select different security levels to provide varying degrees of access to your system.) You might be skeptical of this rather draconian restriction against writing files to your local disk. For example, you may want to build a local database or save data for later use offline. The initial vision seemed to be that eventually everyone would get online to do anything important, but that was soon seen to be impractical (although low-cost “Internet appliances” might someday satisfy the needs of a significant segment of users). The solution is the “signed applet” that uses public-key encryption to verify that an applet does indeed come from where it claims it does. A signed applet can still trash your disk, but the theory is that since you can now hold the applet creator accountable they won’t do vicious things. Java provides a framework for digital signatures so that you will eventually be able to allow an applet to step outside the sandbox if necessary. Digital signatures have missed an important issue, which is the speed that people move around on the Internet. If you download a buggy program and it does something untoward, how long will it be before you discover the damage? It could be days or even weeks. By then, how will you track down the program that’s done it? And what good will it do you at that point?7.Internet vs. intranetThe Web is the most general solution to the client/server problem, so it makes sense that you can use the same technology to solve a subset of the problem, in particular the classic client/server problem within a company. With traditional client/server approaches you have the problem of multiple types of client computers, as well as the difficulty of installing new client software, both of which are handily solved with Web browsers and client-side programming. When Web technology is used for an information network that is restricted to a particular company, it is referred to as an intranet. Intranets provide much greater security than the Internet, since you can physically control access to the servers within your company. In terms of training, it seems that once people und erstand the general concept of a browser it’s much easier for them to deal with differences in the way pages and applets look, so the learning curve for new kinds of systems seems to be reduced.The security problem brings us to one of the divisions that seems to be automatically forming in the world of client-side programming. If your program is running on the Internet, you don’t know what platform it will be working under, and you want to be extra careful that you don’t disseminate buggy code. You need something cross-platform and secure, like a scripting language or Java.If you’re running on an intranet, you might have a different set of constraints. It’s not uncommon that your machines could all be Intel/Windows platforms. On an intranet, you’re respon sible for the quality of your own code and can repair bugs when they’re discovered. In addition, you might already have a body of legacy code that you’ve been using in a more traditional client/server approach, whereby you must physically install client programs every time you do an upgrade. The time wasted in installing upgrades is the most compelling reason to move to browsers, because upgrades are invisible and automatic. If you are involved in such an intranet, the most sensible approach to take is the shortest path that allows you to use your existing code base, rather than trying to recode your programs in a new language.When faced with this bewildering array of solutions to the client-side programming problem, the best plan of attack is a cost-benefit analysis. Consider the constraints of your problem and what would be the shortest path to your solution. Since client-side programming is still programming, it’s always a good idea to take the fastest development approach for your particular situation. This is an aggressive stance to prepare for inevitable encounters with the problems of program development.8.Server-side programmingThis whole discussion has ignored the issue of server-side programming. What happens when you make a request of a server? Most of the time the request is simply “send me this file.” Your browser then interprets the file in some appropriate fashion: as an HTML page, a graphic image, a Java applet, a script program, etc. A more complicated request to a server generally involves a database transaction. A common scenario involves a request for a complex database search, which the server then formats into an HTML page and sends to you as the result. (Of course, if the client has more intelligence via Java or a scripting language, the raw data can be sent and formatted at the client end, which will be faster and less load on the server.) Or you might want to register your name in a database when you join a group or place an order, which will involve changes to that database. These database requests must be processed via some code on the server side, which is generally referred to as server-side programming. Traditionally, server-side programming has been performed using Perl and CGI scripts, but more sophisticated systems have been appearing. These include Java-based Web servers that allow you to perform all your server-side programming in Java by writing what are called servlets. Servlets and their offspring, JSPs, are two of the most compelling reasons that companies who develop Web sites are moving to Java, especially because they eliminate the problems of dealing with differently abled browsers.9. separate arena: applicationsMuch of the brouhaha over Java has been over applets. Java is actually a general-purpose programming language that can solve any type of problem—at least in theory. And as pointed out previously, there might be more effective ways to solve most client/server problems. When you move out of the applet arena (and simultaneously release the restrictions, such as the one against writing to disk) you enter the world of general-purpose applications that run standalone, without a Web browser, just like any ordinary program does. Here, Java’s strength is not only in its portability, but also its programmability. As you’l l see throughout this book, Java has many features that allow you to create robust programs in a shorter period than with previous programming languages. Be aware that this is a mixed blessing. You pay for the improvements through slower execution speed (although there is significant work going on in this area—JDK 1.3, in particular, introduces the so-called “hotspot” performance improvements). Like any language, Java has built-in limitations that might make it inappropriate to solve certain types of programming problems. Java is a rapidly evolving language, however, and as each new release comes out it becomes more and more attractive for solving larger sets of problems.Java和因特网既然Java不过另一种类型的程序设计语言，大家可能会奇怪它为什么值得如此重视，为什么还有这么多的人认为它是计算机程序设计的一个里程碑呢？如果您来自一个传统的程序设计背景，那么答案在刚开始的时候并不是很明显。

计算机 java 外文翻译外文文献英文文献

英文原文:Title: Business Applications of Java. Author: Erbschloe, Michael, Business Applications of Java -- Research Starters Business, 2008DataBase: Research Starters - BusinessBusiness Applications of JavaThis article examines the growing use of Java technology in business applications. The history of Java is briefly reviewed along with the impact of open standards on the growth of the World Wide Web. Key components and concepts of the Java programming language are explained including the Java Virtual Machine. Examples of how Java is being used bye-commerce leaders is provided along with an explanation of how Java is used to develop data warehousing, data mining, and industrial automation applications. The concept of metadata modeling and the use of Extendable Markup Language (XML) are also explained.Keywords Application Programming Interfaces (API's); Enterprise JavaBeans (EJB); Extendable Markup Language (XML); HyperText Markup Language (HTML); HyperText Transfer Protocol (HTTP); Java Authentication and Authorization Service (JAAS); Java Cryptography Architecture (JCA); Java Cryptography Extension (JCE); Java Programming Language; Java Virtual Machine (JVM); Java2 Platform, Enterprise Edition (J2EE); Metadata Business Information Systems > Business Applications of JavaOverviewOpen standards have driven the e-business revolution. Networking protocol standards, such as Transmission Control Protocol/Internet Protocol (TCP/IP), HyperText Transfer Protocol (HTTP), and the HyperText Markup Language (HTML) Web standards have enabled universal communication via the Internet and the World Wide Web. As e-business continues to develop, various computing technologies help to drive its evolution.The Java programming language and platform have emerged as major technologies for performing e-business functions. Java programming standards have enabled portability of applications and the reuse of application components across computing platforms. Sun Microsystems' Java Community Process continues to be a strong base for the growth of the Java infrastructure and language standards. This growth of open standards creates new opportunities for designers and developers of applications and services (Smith, 2001).Creation of Java TechnologyJava technology was created as a computer programming tool in a small, secret effort called "the Green Project" at Sun Microsystems in 1991. The Green Team, fully staffed at 13 people and led by James Gosling, locked themselves away in an anonymous office on Sand Hill Road in Menlo Park, cut off from all regular communications with Sun, and worked around the clock for18 months. Their initial conclusion was that at least one significant trend would be the convergence of digitally controlled consumer devices and computers. A device-independent programming language code-named "Oak" was the result.To demonstrate how this new language could power the future of digital devices, the Green Team developed an interactive, handheld home-entertainment device controller targeted at the digital cable television industry. But the idea was too far ahead of its time, and the digital cable television industry wasn't ready for the leap forward that Java technology offered them. As it turns out, the Internet was ready for Java technology, and just in time for its initial public introduction in 1995, the team was able to announce that the Netscape Navigator Internet browser would incorporate Java technology ("Learn about Java," 2007).Applications of JavaJava uses many familiar programming concepts and constructs and allows portability by providing a common interface through an external Java Virtual Machine (JVM). A virtual machine is a self-contained operating environment, created by a software layer that behaves as if it were a separate computer. Benefits of creating virtual machines include better exploitation of powerful computing resources and isolation of applications to prevent cross-corruption and improve security (Matlis, 2006).The JVM allows computing devices with limited processors or memory to handle more advanced applications by calling up software instructions inside the JVM to perform most of the work. This also reduces the size and complexity of Java applications because many of the core functions and processing instructions were built into the JVM. As a result, software developers no longer need to re-create the same application for every operating system. Java also provides security by instructing the application to interact with the virtual machine, which served as a barrier between applications and the core system, effectively protecting systems from malicious code.Among other things, Java is tailor-made for the growing Internet because it makes it easy to develop new, dynamic applications that could make the most of the Internet's power and capabilities. Java is now an open standard, meaning that no single entity controls its development and the tools for writing programs in the language are available to everyone. The power of open standards like Java is the ability to break down barriers and speed up progress.Today, you can find Java technology in networks and devices that range from the Internet and scientific supercomputers to laptops and cell phones, from Wall Street market simulators to home game players and credit cards. There are over 3 million Java developers and now there are several versions of the code. Most large corporations have in-house Java developers. In addition, the majority of key software vendors use Java in their commercial applications (Lazaridis, 2003).ApplicationsJava on the World Wide WebJava has found a place on some of the most popular websites in the world and the uses of Java continues to grow. Java applications not only provide unique user interfaces, they also help to power the backend of websites. Two e-commerce giants that everybody is probably familiar with (eBay and Amazon) have been Java pioneers on the World Wide Web.eBayFounded in 1995, eBay enables e-commerce on a local, national and international basis with an array of Web sites-including the eBay marketplaces, PayPal, Skype, and -that bring together millions of buyers and sellers every day. You can find it on eBay, even if you didn't know it existed. On a typical day, more than 100 million items are listed on eBay in tens of thousands of categories. Recent listings have included a tunnel boring machine from the Chunnel project, a cup of water that once belonged to Elvis, and theV olkswagen that Pope Benedict XVI owned before he moved up to the Popemobile. More than one hundred million items are available at any given time, from the massive to the miniature, the magical to the mundane, on eBay; the world's largest online marketplace.eBay uses Java almost everywhere. To address some security issues, eBay chose Sun Microsystems' Java System Identity Manager as the platform for revamping its identity management system. The task at hand was to provide identity management for more than 12,000 eBay employees and contractors.Now more than a thousand eBay software developers work daily with Java applications. Java's inherent portability allows eBay to move to new hardware to take advantage of new technology, packaging, or pricing, without having to rewrite Java code ("eBay drives explosive growth," 2007).Amazon (a large seller of books, CDs, and other products) has created a Web Service application that enables users to browse their product catalog and place orders. uses a Java application that searches the Amazon catalog for books whose subject matches a user-selected topic. The application displays ten books that match the chosen topic, and shows the author name, book title, list price, Amazon discount price, and the cover icon. The user may optionally view one review per displayed title and make a buying decision (Stearns & Garishakurthi, 2003).Java in Data Warehousing & MiningAlthough many companies currently benefit from data warehousing to support corporate decision making, new business intelligence approaches continue to emerge that can be powered by Java technology. Applications such as data warehousing, data mining, Enterprise Information Portals (EIP's), and Knowledge Management Systems (which can all comprise a businessintelligence application) are able to provide insight into customer retention, purchasing patterns, and even future buying behavior.These applications can not only tell what has happened but why and what may happen given certain business conditions; allowing for "what if" scenarios to be explored. As a result of this information growth, people at all levels inside the enterprise, as well as suppliers, customers, and others in the value chain, are clamoring for subsets of the vast stores of information such as billing, shipping, and inventory information, to help them make business decisions. While collecting and storing vast amounts of data is one thing, utilizing and deploying that data throughout the organization is another.The technical challenges inherent in integrating disparate data formats, platforms, and applications are significant. However, emerging standards such as the Application Programming Interfaces (API's) that comprise the Java platform, as well as Extendable Markup Language (XML) technologies can facilitate the interchange of data and the development of next generation data warehousing and business intelligence applications. While Java technology has been used extensively for client side access and to presentation layer challenges, it is rapidly emerging as a significant tool for developing scaleable server side programs. The Java2 Platform, Enterprise Edition (J2EE) provides the object, transaction, and security support for building such systems.Metadata IssuesOne of the key issues that business intelligence developers must solve is that of incompatible metadata formats. Metadata can be defined as information about data or simply "data about data." In practice, metadata is what most tools, databases, applications, and other information processes use to define, relate, and manipulate data objects within their own environments. It defines the structure and meaning of data objects managed by an application so that the application knows how to process requests or jobs involving those data objects. Developers can use this schema to create views for users. Also, users can browse the schema to better understand the structure and function of the database tables before launching a query.To address the metadata issue, a group of companies (including Unisys, Oracle, IBM, SAS Institute, Hyperion, Inline Software and Sun) have joined to develop the Java Metadata Interface (JMI) API. The JMI API permits the access and manipulation of metadata in Java with standard metadata services. JMI is based on the Meta Object Facility (MOF) specification from the Object Management Group (OMG). The MOF provides a model and a set of interfaces for the creation, storage, access, and interchange of metadata and metamodels (higher-level abstractions of metadata). Metamodel and metadata interchange is done via XML and uses the XML Metadata Interchange (XMI) specification, also from the OMG. JMI leverages Java technology to create an end-to-end data warehousing and business intelligence solutions framework.Enterprise JavaBeansA key tool provided by J2EE is Enterprise JavaBeans (EJB), an architecture for the development of component-based distributed business applications. Applications written using the EJB architecture are scalable, transactional, secure, and multi-user aware. These applications may be written once and then deployed on any server platform that supports J2EE. The EJB architecture makes it easy for developers to write components, since they do not need to understand or deal with complex, system-level details such as thread management, resource pooling, and transaction and security management. This allows for role-based development where component assemblers, platform providers and application assemblers can focus on their area of responsibility further simplifying application development.EJB's in the Travel IndustryA case study from the travel industry helps to illustrate how such applications could function. A travel company amasses a great deal of information about its operations in various applications distributed throughout multiple departments. Flight, hotel, and automobile reservation information is located in a database being accessed by travel agents worldwide. Another application contains information that must be updated with credit and billing history from a financial services company. Data is periodically extracted from the travel reservation system databases to spreadsheets for use in future sales and marketing analysis.Utilizing J2EE, the company could consolidate application development within an EJB container, which can run on a variety of hardware and software platforms allowing existing databases and applications to coexist with newly developed ones. EJBs can be developed to model various data sets important to the travel reservation business including information about customer, hotel, car rental agency, and other attributes.Data Storage & AccessData stored in existing applications can be accessed with specialized connectors. Integration and interoperability of these data sources is further enabled by the metadata repository that contains metamodels of the data contained in the sources, which then can be accessed and interchanged uniformly via the JMI API. These metamodels capture the essential structure and semantics of business components, allowing them to be accessed and queried via the JMI API or to be interchanged via XML. Through all of these processes, the J2EE infrastructure ensures the security and integrity of the data through transaction management and propagation and the underlying security architecture.To consolidate historical information for analysis of sales and marketing trends, a data warehouse is often the best solution. In this example, data can be extracted from the operational systems with a variety of Extract, Transform and Load tools (ETL). The metamodels allow EJBsdesigned for filtering, transformation, and consolidation of data to operate uniformly on data from diverse data sources as the bean is able to query the metamodel to identify and extract the pertinent fields. Queries and reports can be run against the data warehouse that contains information from numerous sources in a consistent, enterprise-wide fashion through the use of the JMI API (Mosher & Oh, 2007).Java in Industrial SettingsMany people know Java only as a tool on the World Wide Web that enables sites to perform some of their fancier functions such as interactivity and animation. However, the actual uses for Java are much more widespread. Since Java is an object-oriented language like C++, the time needed for application development is minimal. Java also encourages good software engineering practices with clear separation of interfaces and implementations as well as easy exception handling.In addition, Java's automatic memory management and lack of pointers remove some leading causes of programming errors. Most importantly, application developers do not need to create different versions of the software for different platforms. The advantages available through Java have even found their way into hardware. The emerging new Java devices are streamlined systems that exploit network servers for much of their processing power, storage, content, and administration.Benefits of JavaThe benefits of Java translate across many industries, and some are specific to the control and automation environment. For example, many plant-floor applications use relatively simple equipment; upgrading to PCs would be expensive and undesirable. Java's ability to run on any platform enables the organization to make use of the existing equipment while enhancing the application.IntegrationWith few exceptions, applications running on the factory floor were never intended to exchange information with systems in the executive office, but managers have recently discovered the need for that type of information. Before Java, that often meant bringing together data from systems written on different platforms in different languages at different times. Integration was usually done on a piecemeal basis, resulting in a system that, once it worked, was unique to the two applications it was tying together. Additional integration required developing a brand new system from scratch, raising the cost of integration.Java makes system integration relatively easy. Foxboro Controls Inc., for example, used Java to make its dynamic-performance-monitor software package Internet-ready. This software provides senior executives with strategic information about a plant's operation. The dynamic performance monitor takes data from instruments throughout the plant and performs variousmathematical and statistical calculations on them, resulting in information (usually financial) that a manager can more readily absorb and use.ScalabilityAnother benefit of Java in the industrial environment is its scalability. In a plant, embedded applications such as automated data collection and machine diagnostics provide critical data regarding production-line readiness or operation efficiency. These data form a critical ingredient for applications that examine the health of a production line or run. Users of these devices can take advantage of the benefits of Java without changing or upgrading hardware. For example, operations and maintenance personnel could carry a handheld, wireless, embedded-Java device anywhere in the plant to monitor production status or problems.Even when internal compatibility is not an issue, companies often face difficulties when suppliers with whom they share information have incompatible systems. This becomes more of a problem as supply-chain management takes on a more critical role which requires manufacturers to interact more with offshore suppliers and clients. The greatest efficiency comes when all systems can communicate with each other and share information seamlessly. Since Java is so ubiquitous, it often solves these problems (Paula, 1997).Dynamic Web Page DevelopmentJava has been used by both large and small organizations for a wide variety of applications beyond consumer oriented websites. Sandia, a multiprogram laboratory of the U.S. Department of Energy's National Nuclear Security Administration, has developed a unique Java application. The lab was tasked with developing an enterprise-wide inventory tracking and equipment maintenance system that provides dynamic Web pages. The developers selected Java Studio Enterprise 7 for the project because of its Application Framework technology and Web Graphical User Interface (GUI) components, which allow the system to be indexed by an expandable catalog. The flexibility, scalability, and portability of Java helped to reduce development time and costs (Garcia, 2004)IssueJava Security for E-Business ApplicationsTo support the expansion of their computing boundaries, businesses have deployed Web application servers (WAS). A WAS differs from a traditional Web server because it provides a more flexible foundation for dynamic transactions and objects, partly through the exploitation of Java technology. Traditional Web servers remain constrained to servicing standard HTTP requests, returning the contents of static HTML pages and images or the output from executed Common Gateway Interface (CGI ) scripts.An administrator can configure a WAS with policies based on security specifications for Java servlets and manage authentication and authorization with Java Authentication andAuthorization Service (JAAS) modules. An authentication and authorization service can be written in Java code or interface to an existing authentication or authorization infrastructure. For a cryptography-based security infrastructure, the security server may exploit the Java Cryptography Architecture (JCA) and Java Cryptography Extension (JCE). To present the user with a usable interaction with the WAS environment, the Web server can readily employ a form of "single sign-on" to avoid redundant authentication requests. A single sign-on preserves user authentication across multiple HTTP requests so that the user is not prompted many times for authentication data (i.e., user ID and password).Based on the security policies, JAAS can be employed to handle the authentication process with the identity of the Java client. After successful authentication, the WAS security collaborator consults with the security server. The WAS environment authentication requirements can be fairly complex. In a given deployment environment, all applications or solutions may not originate from the same vendor. In addition, these applications may be running on different operating systems. Although Java is often the language of choice for portability between platforms, it needs to marry its security features with those of the containing environment.Authentication & AuthorizationAuthentication and authorization are key elements in any secure information handling system. Since the inception of Java technology, much of the authentication and authorization issues have been with respect to downloadable code running in Web browsers. In many ways, this had been the correct set of issues to address, since the client's system needs to be protected from mobile code obtained from arbitrary sites on the Internet. As Java technology moved from a client-centric Web technology to a server-side scripting and integration technology, it required additional authentication and authorization technologies.The kind of proof required for authentication may depend on the security requirements of a particular computing resource or specific enterprise security policies. To provide such flexibility, the JAAS authentication framework is based on the concept of configurable authenticators. This architecture allows system administrators to configure, or plug in, the appropriate authenticators to meet the security requirements of the deployed application. The JAAS architecture also allows applications to remain independent from underlying authentication mechanisms. So, as new authenticators become available or as current authentication services are updated, system administrators can easily replace authenticators without having to modify or recompile existing applications.At the end of a successful authentication, a request is associated with a user in the WAS user registry. After a successful authentication, the WAS consults security policies to determine if the user has the required permissions to complete the requested action on the servlet. This policy canbe enforced using the WAS configuration (declarative security) or by the servlet itself (programmatic security), or a combination of both.The WAS environment pulls together many different technologies to service the enterprise. Because of the heterogeneous nature of the client and server entities, Java technology is a good choice for both administrators and developers. However, to service the diverse security needs of these entities and their tasks, many Java security technologies must be used, not only at a primary level between client and server entities, but also at a secondary level, from served objects. By using a synergistic mix of the various Java security technologies, administrators and developers can make not only their Web application servers secure, but their WAS environments secure as well (Koved, 2001).ConclusionOpen standards have driven the e-business revolution. As e-business continues to develop, various computing technologies help to drive its evolution. The Java programming language and platform have emerged as major technologies for performing e-business functions. Java programming standards have enabled portability of applications and the reuse of application components. Java uses many familiar concepts and constructs and allows portability by providing a common interface through an external Java Virtual Machine (JVM). Today, you can find Java technology in networks and devices that range from the Internet and scientific supercomputers to laptops and cell phones, from Wall Street market simulators to home game players and credit cards.Java has found a place on some of the most popular websites in the world. Java applications not only provide unique user interfaces, they also help to power the backend of websites. While Java technology has been used extensively for client side access and in the presentation layer, it is also emerging as a significant tool for developing scaleable server side programs.Since Java is an object-oriented language like C++, the time needed for application development is minimal. Java also encourages good software engineering practices with clear separation of interfaces and implementations as well as easy exception handling. Java's automatic memory management and lack of pointers remove some leading causes of programming errors. The advantages available through Java have also found their way into hardware. The emerging new Java devices are streamlined systems that exploit network servers for much of their processing power, storage, content, and administration.中文翻译:标题：Java的商业应用。

java中英文文献

南京理工大学紫金学院毕业设计(论文) 外文资料翻译系：运算机系专业：运算机科学与技术姓名：学号：０９０６０１４１６外文出处：(用外文写) Ghosh,D..Java Object-oriented programming[J]. IEEE Transactions on Software Engineering,2020, 13(3):42-45. 附件：１．外文资料翻译译文；２．外文原文。

指导教师评语：签名：年月日注：请将该封面与附件装订成册。

附件１：外文资料翻译译文Java 的面向对象编程——面向对象编程和它的关键技术—继承和多态性软件的重用能够节省程序开发时刻。

它鼓舞重复利用已经调试好的高质量的软件，从而减少系统运行后可能显现的问题。

这些都是令人振奋的可能性。

多态性许诺咱们用统一的风格编写程序，来处置多种已存在的类和特定的相关类。

利用多态性咱们能够方便地向系统中添加新的功能。

继承和多态关于解决软件的复杂性是一种有效可行的技术。

当创建一个新的类时，而不用完整的写出新的实例变量和实例方式，程序员会指定新的类继承已概念的超类的实例变量和实例方式。

那个新的类被称为一个子类。

每一个子类本身以后亦可有新的子类，而其本身将成为父类。

一个类的直接父类确实是该类所直接继承的类（通过关键字extends 继承）。

一个间接超类是通过从两级或更多级以上的类继承而来的。

例如，从类JApplet （包javax. swing中）扩展来的类Applet （包java. applet）。

一个类单一的从一个父类继承而来。

Java不支持多重继承（而C++能够），但它支持接口的概念。

接口能够使Java 实现许多通过量重继承才能实现的优势而没有关联的问题。

咱们将在本章讨论的接口的详细内容。

咱们会给出创建和利用接口的一样规律和具体实例。

一个子类通常添加自己的实例变量和自己的实例方式，因此子类通常比父类大。

一个子类比它的父类更具体而且代表一组更小、更专业的对象。

计算机系 Java EE 外文翻译外文文献英文文献

外文科技资料翻译英文原文The Java EE Platform is the leading enterprise web server. The Adobe Flash Platform is the leader in the rich Internet application space. Using both, developers can deliver compelling, data-centric applications that leverage the benefits of an enterprise back-end solution and a great user experience.In this article, you learn about the architecture of applications built using Flex and Java including:(1)An overview of the client/server architecture.(2)The different ways the client and server can communicate.(3)An introduction to Flash Remoting and why and how you use it.(4)How to integrate a Flex application with your security framework.(5)An overview of how to build Flex applications using events, states,MXML components, and modules.(6)An introduction to developing a Flex application with real-time serverdata push.(7)How to boost productivity developing data-intensive applicationsusing the Data Management service in LiveCycle Data Services.(8)An overview of model driven development using Flash Builder andLiveCycle Data Services to generate client and server-side code.(9)How to deploy a Flex application on a portal server.(10)Be sure to also watch the video Introduction to Flex 4 and Javaintegration.(11)To learn more about the technologies used to build these applications,read The technologies for building Flex and Java applications article.Client/server architectureFlex and Java applications use a multi-tier architecture where the presentation tier is the Flex application, the business or application tier is the Java EE server and code, and the data tier is the database. You can write the back-end code just as you normally would for a Java application, modeling your objects, defining your database, using an object-relational framework such as Hibernate or EJB 3, and writing the business logic to query and manipulate these objects. The business tier must be exposed for access via HTTP from the Flex application and will be used to move the data between the presentation and data tiers.Typical HTML applications consist of multiple pages and as a user navigates between them, the application data must be passed along so the application itself (the collection of pages and functionality it consists of) can maintain state. In contrast, Flex applications, by nature, are stateful. A Flex application is embedded in a single HTML page that the user does not leave and is rendered by Flash Player. The Flex application can dynamically change views and send and retrieve data asynchronously to the server in the background, updating but never leaving the single application interface (see Figure 1) (similar to the functionality provided by the XMLHttpRequest API with JavaScript.)Figure 1. The client/server architecture.Client/server communicationFlex applications can communicate with back-end servers using either direct socket connections or more commonly, through HTTP. The Flex framework has three remote procedure call APIs that communicate with a server over HTTP: HTTPService, WebService, and RemoteObject. All three wrap Flash Player'sHTTP connectivity, which in turn, uses the browser's HTTP library. Flex applications cannot connect directly to a remote database.You use HTTPService to make HTTP requests to JSP or XML files, to RESTful web services, or to other server files that return text over HTTP. You specify the endpoint URL, listener functions (the callback functions to be invoked when the HTTPService request returns a successful or unsuccessful response), and a data type for the returned data (what type of data structure it should be translated into once received in the Flex application). You can specify the data to be handled as raw text and assigned to a String variable or converted to XML, E4X, or plain old ActionScript objects. If you get back JSON, you can use the Adobe Flex corelib package of classes to deserialize the JSON objects into ActionScript objects. To make calls to SOAP based web services, you can use the HTTPService API or the more specialized WebService API, which automatically handles the serialization and deserialization of SOAP formatted text to ActionScript data types and vice versa.The third option for making remote procedure calls is to use the RemoteObject API. It makes a Flash Remoting request to a method of a server-side Java class that returns binary Action Message Format over HTTP. When possible, use Flash Remoting whose binary data transfer format enables applications to load data up to 10 times faster than with the more verbose, text-based formats such as XML, JSON, or SOAP (see Figure 2). To see a comparison of AMF to other text-based serialization technologies, see James Ward's Census RIA Benchmark application.Figure 2. Methods for connecting Flex and Java.Flash RemotingFlash Remoting is a combination of client and server-side functionality that together provides a call-and-response model for accessing server-side objects from Flash Platform applications as if they were local objects. It provides transparent data transfer between ActionScript and server-side data types, handling the serialization into Action Message Format (AMF), deserialization, and data marshaling between the client and the server.Flash Remoting uses client-side functionality built in to Flash Player and server-side functionality that is built in to some servers (like ColdFusion and Zend) but must be installed on other servers (as BlazeDS or LiveCycle Data Services on Java EE servers, WebORB or FluorineFX on .NET servers, the Zend framework or amfphp on PHP servers, and more). See the technologies for building Flex and Java applications article for more details about BlazeDS and LiveCycle Data Services.BlazeDS and LiveCycle Data Services use a message-based framework to send data back and forth between the client and server. They provide Remoting, Proxying, and Messaging services, and for LiveCycle, an additional Data Management service. The Flex application sends a request to the server and the request is routed to an endpoint on the server. From the endpoint, the request is passed to the MessageBroker, the BlazeDS and LiveCycle Data Services engine that handles all the requests and routes them through a chain of Java objects to the destination, the Java class with the method to invoke (see Figure 3).Figure 3. Flash Remoting architecture.AMFAMF is a binary format used to serialize ActionScript objects and facilitate data exchange between Flash Platform applications and remote services over the Internet. Adobe publishes this protocol; the latest is AMF 3 Specification for ActionScript 3. You can find tables listing the data type mappings when converting from ActionScript to Java and Java to ActionScript here.For custom or strongly typed objects, public properties (including those defined with get and set methods) are serialized and sent from the Flex application to the server or from the server to the Flex application as properties of a general 0bject. To enable mapping between the corresponding client and server-side objects, you use the same property names in the Java and ActionScript classes and then in the ActionScript class, you use the [RemoteClass] metadata tag to create an ActionScript object that maps directly to the Java object.Here is an example Employee ActionScript class that maps to a server-side Employee Java DTO located in the services package on the server.package valueobjects.Employee{ [Bindable] [RemoteClass(alias="services.Employee")] public class Employee { public var id:int; public var firstName:String; public var lastName:String; (...) } }Installing BlazeDS or LiveCycle Data ServicesTo use Flash Remoting with BlazeDS or LiveCycle Data Services, you need to install and configure the necessary server-side files. For BlazeDS, you can download it as a WAR file which you deploy as a web application or as a turnkey solution. The turnkey download contains a ready-to-use version of Tomcat in which the the BlazeDS WAR file has already been deployed and configured along with a variety of sample applications. Similarly, for LiveCycle Data Services, the installer lets you choose to install LiveCycle with an integrated Tomcat server or as a LiveCycle Data Services web application.In either scenario a web application called blazeds or lcds (usually appended by a version number) is created. You can modify and build out this application with your Java code, or more typically, you can copy the JAR files and configuration files the blazeds or lcds web application contains and add them to an existing Java web application on the server (see Figure 4).Figure 4. The required BlazeDS or LiveCycle Data Services files.Modifying web.xmlIf copying the files to a different web application, you also need to modify the web.xml file to define a session listener for HttpFlexSession and a servlet mapping for MessageBroker, which handles all the requests and passes them off to the correct server-side Java endpoints. You can copy and paste these from the original blazeds or lcds web application web.xml file. <listener> <listener-class>flex.messaging.HttpFlexSession</listener-class> </listener>  <servlet><servlet-name>MessageBrokerServlet</servlet-name><display-name>MessageBrokerServlet</display-name><servlet-class>flex.messaging.MessageBrokerServlet</servlet-class><init-param> <param-name>services.configuration.file</param-name><param-value>/WEB-INF/flex/services-config.xml</param-value></init-param> <load-on-startup>1</load-on-startup> </servlet><servlet-mapping> <servlet-name>MessageBrokerServlet</servlet-name><url-pattern>/messagebroker/*</url-pattern> </servlet-mapping>Optionally, you may also want to copy and paste (and uncomment) the mapping for RDSDispatchServlet, which is used for RDS (Remote Data Service) access with the data service creation feature in Flash Builder 4 that introspects a server-side service and generates corresponding client-side code. See the model driven development section for more details.<servlet> <servlet-name>RDSDispatchServlet</servlet-name><display-name>RDSDispatchServlet</display-name><servlet-class>flex.rds.server.servlet.FrontEndServlet</servlet-class><init-param> <param-name>useAppserverSecurity</param-name><param-value>false</param-value> </init-param><load-on-startup>10</load-on-startup> </servlet> <servlet-mappingid="RDS_DISPATCH_MAPPING"><servlet-name>RDSDispatchServlet</servlet-name><url-pattern>/CFIDE/main/ide.cfm</url-pattern> </servlet-mapping> Reviewing services-config.xmlFor Flash Remoting, the client sends a request to the server to be processed and the server returns a response to the client containing the results. You configure these requests by modifying the services-config.xml and remoting-config.xml files located in the /WEB-INF/flex/ folder for the web application.The services-config.xml file defines different channels that can be used when making a request. Each channel definition specifies the network protocol and the message format to be used for a request and the endpoint to deliver the messages to on the server. The Java-based endpoints unmarshal the messages in a protocol-specific manner and then pass the messages in Java form to the MessageBroker which sends them to the appropriate service destination (you'll see how to define these next).<channels> <channel-definition id="my-amf"class="mx.messaging.channels.AMFChannel"> <endpointurl="http://{}:{server.port}/{context.root}/messagebroker/amf" class="flex.messaging.endpoints.AMFEndpoint"/> </channel-definition><channel-definition id="my-secure-amf"class="mx.messaging.channels.SecureAMFChannel"> <endpointurl="https://{}:{server.port}/{context.root}/messagebroker/amfsecu re" class="flex.messaging.endpoints.SecureAMFEndpoint"/></channel-definition> (...) </channels>Defining destinationsIn the remoting-config.xml file, you define the destinations (named mappings to Java classes) to which the MessageBroker passes the messages. You set the source property to the fully qualified class name of a Java POJO with a no argument constructor that is located in a source path, usually achieved by placing it in the web application's /WEBINF/classes/ directory or in a JAR file in the /WEBINF/lib/ directory. You can access EJBs and other objects stored in the Java Naming and Directory Interface (JNDI) by calling methods on a destination that is a service facade class that looks up an object in JNDI and calls its methods.You can access stateless or stateful Java objects by setting the scope property to application, session, or request (the default). The instantiation and management of the server-side objects referenced is handled by BlazeDS or LiveCycle Data Services.<service id="remoting-service"class="flex.messaging.services.RemotingService"> <adapters><adapter-definition id="java-object"class="flex.messaging.services.remoting.adapters.JavaAdapter" default="true"/> </adapters> <default-channels> <channel ref="my-amf"/> </default-channels> <destination id="employeeService"> <properties><source>services.EmployeeService</source> <scope>application</scope></properties> </destination> </service>You can also specify channels for individual destinations.<destination id="employeeService " channels="my-secure-amf">Lastly, you use these destinations when defining RemoteObject instances in a Flex application.<s:RemoteObject id="employeeSvc" destination="employeeService"/>SecurityIn many applications, access to some or all server-side resources must be restricted to certain users. Many Java EE applications use container managed security in which user authentication (validating a user) and user authorization (determining what the user has access to—which is often role based) are performed against the Realm, an existing store of usernames, passwords, and user roles. The Realm is configured on your Java EE server to be a relational database, an LDAP directory server, an XML document, or to use a specific authentication and authorization framework.To integrate a Flex application with the Java EE security framework so that access to server-side resources is appropriately restricted, you add security information to the BlazeDS or LiveCycle Data Services configuration files (details follow below) and then typically in the Flex application, create a form to obtain login credentials from the user which are passed to the server to be authenticated. The user credentials are then passed to the server automatically with all subsequent requests.Modifying services-config.xmlIn the BlazeDS or LiveCycle Data Services services-config.xml file, you need to specify the "login command" for your application server in the <security> tag. BlazeDS and LiveCycle Data Services supply the following login commands: TomcatLoginCommand (for both Tomcat and JBoss), JRunLoginCommand, WeblogicLoginCommand, WebSphereLoginCommand, OracleLoginCommand. These are all defined in the XML file and you just need to uncomment the appropriate one.You also need to define a security constraint that you specify to use either basic or custom authentication and if desired, one or more roles. To do custom authentication with Tomat or JBoss, you also need to add some extra classes tothe web application for integrating with the security framework used by the Jave EE application server and modify a couple of configuration files. Mode details can be found here.<services-config> <security> <login-commandclass="flex.messaging.security.TomcatLoginCommand" server="Tomcat"><per-client-authentication>false</per-client-authentication></login-command> <security-constraint id="trusted"><auth-method>Custom</auth-method> <roles> <role>employees</role><role>managers</role> </roles> </security-constraint> </security> ...</services-config>Modifying remoting-config.xmlNext, in your destination definition, you need to reference the security constraint:<destination id="employeeService"> <properties><source>services.EmployeeService</source> </properties> <security><security-constraint ref="trusted"/> </security> </destination>You can also define default security constraints for all destinations and/or restrict access to only specific methods that can use different security constraints.The default channel, my-amf, uses HTTP. You can change one or more of the destinations to use the my-secure-amf channel that uses HTTPS:<destination id="employeeService"> <channels> <channelref="my-secure-amf"/> </channels> ... </destination>where my-secure-amf is defined in the services-config.xml file: <channel-definition id="my-secure-amf" class="mx.messaging.channels.SecureAMFChannel"> <endpointurl="https://{}:{server.port}/{context.root}/messagebroker/amfsecu re" class="flex.messaging.endpoints.SecureAMFEndpoint"/></channel-definition>Adding code to the Flex applicationThat covers the server-side setup. Now, if you are using custom authentication, you need to create a form in the Flex application to retrieve a username and password from the user and then pass these credentials to the server by calling the ChannelSet.login() method and then listening for its result and fault events. A result event indicates that the login (the authentication) occurred successfully, and a fault event indicates the login failed. The credentials are applied to all services connected over the same ChannelSet. For basic authentication, you don’t have to add anything to your Flex application. The browser opens a login dialog box when the application first attempts to connect to a destination.Your application can now make Flash Remoting requests to server destinations just as before, but now the user credentials are automatically sent with every request (for both custom and basic authentication). If the destination or methods of the destination have authorization roles specified which are not met by the logged in user, the call will return a fault event. To remove the credentials and log out the user, you use the ChannelSet.logout() method.中文译文Java EE平台是全球领先的企业Web服务器。

java英文参考文献

java英⽂参考⽂献java英⽂参考⽂献汇编导语：Java是⼀门⾯向对象编程语⾔，不仅吸收了C++语⾔的各种优点，还摒弃了C++⾥难以理解的多继承、指针等概念，因此Java语⾔具有功能强⼤和简单易⽤两个特征。

下⾯⼩编为⼤家带来java英⽂参考⽂献，供各位阅读和参考。

java英⽂参考⽂献⼀： [1]Irene Córdoba-Sánchez,Juan de Lara. Ann: A domain-specific language for the effective design and validation of Java annotations[J]. Computer Languages, Systems & Structures,2016,:. [2]Marcelo M. Eler,Andre T. Endo,Vinicius H.S. Durelli. An Empirical Study to Quantify the Characteristics of Java Programs that May Influence Symbolic Execution from a Unit Testing Perspective[J]. The Journal of Systems & Software,2016,:. [3]Kebo Zhang,Hailing Xiong. A new version of code Java for 3D simulation of the CCA model[J]. Computer Physics Communications,2016,:. [4]S. Vidal,A. Bergel,J.A. Díaz-Pace,C. Marcos. Over-exposed classes in Java: An empirical study[J]. Computer Languages, Systems & Structures,2016,:. [5]Zeinab Iranmanesh,Mehran S. Fallah. Specification and Static Enforcement of Scheduler-Independent Noninterference in a Middleweight Java[J]. Computer Languages, Systems & Structures,2016,:. [6]George Gabriel Mendes Dourado,Paulo S Lopes De Souza,Rafael R. Prado,Raphael Negrisoli Batista,Simone R.S. Souza,Julio C. Estrella,Sarita M. Bruschi,Joao Lourenco. A Suite of Java Message-Passing Benchmarks to Support the Validation of Testing Models, Criteria and Tools[J]. Procedia Computer Science,2016,80:. [7]Kebo Zhang,Junsen Zuo,Yifeng Dou,Chao Li,Hailing Xiong. Version 3.0 of code Java for 3D simulation of the CCA model[J]. Computer Physics Communications,2016,:. [8]Simone Hanazumi,Ana C.~V. de Melo. A Formal Approach to Implement Java Exceptions in Cooperative Systems[J]. The Journal of Systems & Software,2016,:. [9]Lorenzo Bettini,Ferruccio Damiani. Xtraitj : Traits for the Java Platform[J]. The Journal of Systems & Software,2016,:. [10]Oscar Vega-Gisbert,Jose E. Roman,Jeffrey M. Squyres. Design and implementation of Java bindings in OpenMPI[J]. Parallel Computing,2016,:. [11]Stefan Bosse. Structural Monitoring with Distributed-Regional and Event-based NN-Decision Tree Learning Using Mobile Multi-Agent Systems and Common Java Script Platforms[J]. Procedia Technology,2016,26:. [12]Pablo Piedrahita-Quintero,Carlos Trujillo,Jorge Garcia-Sucerquia. JDiffraction : A GPGPU-accelerated JAVA library for numerical propagation of scalar wave fields[J]. Computer Physics Communications,2016,:. [13]Abdelhak Mesbah,Jean-Louis Lanet,Mohamed Mezghiche. Reverse engineering a Java Card memory management algorithm[J]. Computers & Security,2017,66:. [14]G. Bacci,M. Bazzicalupo,A. Benedetti,A. Mengoni. StreamingTrim 1.0: a Java software for dynamic trimming of 16S rRNA sequence data from metagenetic studies[J]. Mol Ecol Resour,2014,14（2）：. [15]Qing‐Wei Xu,Johannes Griss,Rui Wang,Andrew R. Jones,Henning Hermjakob,Juan Antonio Vizcaíno. jmzTab: A Java interface to the mzTab data standard[J]. Proteomics,2014,14（11）：. [16]Rody W. J. Kersten,Bernard E. Gastel,Olha Shkaravska,Manuel Montenegro,Marko C. J. D. Eekelen. ResAna: a resource analysis toolset for （real‐time） JAVA[J]. Concurrency Computat.: Pract. Exper.,2014,26（14）：. [17]Stephan E. Korsholm,Hans S?ndergaard,Anders P. Ravn. A real‐time Java tool chain for resource constrained platforms[J]. Concurrency Computat.: Pract. Exper.,2014,26（14）：. [18]M. Teresa Higuera‐Toledano,Andy Wellings. Introduction to the Special Issue on Java Technologies for Real‐Time and Embedded Systems: JTRES 2012[J]. Concurrency Computat.: Pract. Exper.,2014,26（14）：. [19]Mostafa Mohammadpourfard,Mohammad Ali Doostari,Mohammad Bagher Ghaznavi Ghoushchi,Nafiseh Shakiba. Anew secure Internet voting protocol using Java Card 3 technology and Java information flow concept[J]. Security Comm. Networks,2015,8（2）：. [20]Cédric Teyton,Jean‐Rémy Falleri,Marc Palyart,Xavier Blanc. A study of library migrations in Java[J]. J. Softw. Evol. and Proc.,2014,26（11）：. [21]Sabela Ramos,Guillermo L. Taboada,Roberto R. Expósito,Juan Touri?o. Nonblocking collectives for scalable Java communications[J]. Concurrency Computat.: Pract. Exper.,2015,27（5）：. [22]Dusan Jovanovic,Slobodan Jovanovic. An adaptive e‐learning system for Java programming course, based on Dokeos LE[J]. Comput Appl Eng Educ,2015,23（3）：. [23]Yu Lin,Danny Dig. A study and toolkit of CHECK‐THEN‐ACT idioms of Java concurrent collections[J]. Softw. Test. Verif. Reliab.,2015,25（4）：. [24]Jonathan Passerat?Palmbach,Claude Mazel,David R. C. Hill. TaskLocalRandom: a statistically sound substitute to pseudorandom number generation in parallel java tasks frameworks[J]. Concurrency Computat.: Pract.Exper.,2015,27（13）：. [25]Da Qi,Huaizhong Zhang,Jun Fan,Simon Perkins,Addolorata Pisconti,Deborah M. Simpson,Conrad Bessant,Simon Hubbard,Andrew R. Jones. The mzqLibrary – An open source Java library supporting the HUPO‐PSI quantitative proteomics standard[J]. Proteomics,2015,15（18）：. [26]Xiaoyan Zhu,E. James Whitehead,Caitlin Sadowski,Qinbao Song. 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计算机专业毕业设计论文外文文献中英文翻译——java对象

1 . Introduction To Objects1.1The progress of abstractionAll programming languages provide abstractions. It can be argued that the complexity of the problems you’re able to solve is directly related to the kind and quality of abstraction。

By “kind” I mean，“What is it that you are abstracting?” Assembly language is a small abstraction of the underlying machine. Many so—called “imperative” languages that followed （such as FORTRAN，BASIC, and C) were abstractions of assembly language。

These languages are big improvements over assembly language，but their primary abstraction still requires you to think in terms of the structure of the computer rather than the structure of the problem you are trying to solve。

The programmer must establish the association between the machine model (in the “solution space，” which is the place where you’re modeling that problem, such as a computer) and the model of the problem that is actually being solved (in the “problem space,” which is the place where the problem exists). The effort required to perform this mapping, and the fact that it is extrinsic to the programming language，produces programs that are difficult to write and expensive to maintain，and as a side effect created the entire “programming methods” industry.The alter native to modeling the machine is to model the problem you’re trying to solve。

Java编程思想(Java和因特网)毕业论文外文文献翻译及原文

毕业设计（论文）外文文献翻译文献、资料中文题目：Java编程思想 (Java和因特网)文献、资料英文题目：Thingking in Java（Java and the Internet）文献、资料来源：文献、资料发表（出版）日期：院（部）：专业：班级：姓名：学号：指导教师：翻译日期： 2017.02.14文献来源：Bruce Eckel.Thinking in Java [J]. Pearson Higher Isia Education,2006-2-20.Java编程思想 (Java和因特网)既然Java不过另一种类型的程序设计语言，大家可能会奇怪它为什么值得如此重视，为什么还有这么多的人认为它是计算机程序设计的一个里程碑呢？如果您来自一个传统的程序设计背景，那么答案在刚开始的时候并不是很明显。

Java除了可解决传统的程序设计问题以外，还能解决World Wide Web(万维网)上的编程问题。

1、客户端编程Web最初采用的“服务器－浏览器”方案可提供交互式内容，但这种交互能力完全由服务器提供，为服务器和因特网带来了不小的负担。

服务器一般为客户浏览器产生静态网页，由后者简单地解释并显示出来。

基本HTML语言提供了简单的数据收集机制：文字输入框、复选框、单选钮、列表以及下拉列表等，另外还有一个按钮，只能由程序规定重新设置表单中的数据，以便回传给服务器。

用户提交的信息通过所有Web服务器均能支持的“通用网关接口”（CGI）回传到服务器。

包含在提交数据中的文字指示CGI该如何操作。

最常见的行动是运行位于服务器的一个程序。

那个程序一般保存在一个名为“cgi-bin”的目录中（按下Web页内的一个按钮时，请注意一下浏览器顶部的地址窗，经常都能发现“cgi-bin”的字样）。

大多数语言都可用来编制这些程序，但其中最常见的是Perl。

这是由于Perl是专为文字的处理及解释而设计的，所以能在任何服务器上安装和使用，无论采用的处理器或操作系统是什么。

java-毕业论文外文文献翻译

Advantages of Managed CodeMicrosoft intermediate language shares with Java byte code the idea that it is a low—level language with a simple syntax ，which can be very quickly translated into native machine code。

Having this well-defined universal syntax for code has significant advantages。

Platform independenceFirst，it means that the same file containing byte code instructions can be placed on any platform；at runtime the final stage of compilation can then be easily accomplished so that the code will run on that particular platform. In other words, by compiling to IL we obtain platform independence for 。

NET, in much the same way as compiling to Java byte code gives Java platform independence。

Performance improvementIL is actually a bit more ambitious than Java byte code。

IL is always Just-In—Time compiled （known as JIT），whereas Java byte code was often interpreted。

JAVA外文文献+翻译说课讲解

Java and the InternetIf Java is, in fact, yet another computer programming language, you may question why it is so important and why it is being promoted as a revolutionary step in computer programming. The answer isn’t immediately obvious if you’re coming from a traditional programming perspective. Although Java is very useful for solving traditional stand-alone programming problems, it is also important because it will solve programming problems on the World Wide Web.1.Client-side programmingThe Web’s in itial server-browser design provided for interactive content, but the interactivity was completely provided by the server. The server produced static pages for the client browser, which would simply interpret and display them. Basic HTML contains simple mechanisms for data gathering: text-entry boxes, check boxes, radio boxes, lists and drop-down lists, as well as a button that can only be programmed to reset the data on the form or “submit” the data on the form back to the server. This submission passes through the Common Gateway Interface (CGI) provided on all Web servers. The text within the submission tells CGI what to do with it. The most common action is to run a program located on the server in a directory that’s typically called “cgi-bin.” (If you watch the address window at the top of your browser when you push a button on a Web page, you can sometimes see “cgi-bin” within all the gobbledygook there.) These programs can be written in most languages. Perl is a common choice because it is designed for text manipulation and is interpreted, so it can be installed on any server regardless of processor or operating system. Many powerful Web sites today are built strictly on CGI, and you can in fact do nearly anything with it. However, Web sites built on CGI programs can rapidly become overly complicated to maintain, and there is also the problem of response time. The response of a CGI program depends on how much data mustbe sent, as well as the load on both the server and the Internet. (On top of this, starting a CGI program tends to be slow.) The initial designers of the Web did not foresee how rapidly this bandwidth would be exhausted for the kinds of applications people developed. For example, any sort of dynamic graphing is nearly impossible to perform with consistency because a GIF file must be created and moved from the server to the client for each version of the graph. And you’ve no doubt had direct experience with something as simple as validating the data on an input form. You press the submit button on a page; the data is shipped back to the server; the server starts a CGI program that discovers an error, formats an HTML page informing you of the error, and then sends the page back to you; you must then back up a page and try again. Not only is this slow, it’s inelegant.The solution is client-side programming. Most machines that run Web browsers are powerful engines capable of doing vast work, and with the original static HTML approach they are sitting there, just idly waiting for the server to dish up the next page. Client-side programming means that the Web browser is harnessed to do whatever work it can, and the result for the user is a much speedier and more interactive experience at your Web site.The problem with discussions of client-side prog ramming is that they aren’t very different from discussions of programming in general. The parameters are almost the same, but the platform is different: a Web browser is like a limited operating system. In the end, you must still program, and this accounts for the dizzying array of problems and solutions produced by client-side programming. The rest of this section provides an overview of the issues and approaches in client-side programming.2.Plug-insOne of the most significant steps forward in client-side programming is the development of the plug-in. This is a way for a programmer to add new functionality to the browser by downloading a piece of code that plugs itself into the appropriate spot in the browser. It tells the browser “from now on you canpe rform this new activity.” (You need to download the plug-in only once.) Some fast and powerful behavior is added to browsers via plug-ins, but writing a plug-in is not a trivial task, and isn’t something you’d want to do as part of the process of building a particular site. The value of the plug-in for client-side programming is that it allows an expert programmer to develop a new language and add that language to a browser without the permission of the browser manufacturer. Thus, plug-ins provide a “back door” that allows the creation of new client-side programming languages (although not all languages are implemented as plug-ins).3.Scripting languagesPlug-ins resulted in an explosion of scripting languages. With a scripting language you embed the source code for your client-side program directly into the HTML page, and the plug-in that interprets that language is automatically activated while the HTML page is being displayed. Scripting languages tend to be reasonably easy to understand and, because they are simply text that is part of an HTML page, they load very quickly as part of the single server hit required to procure that page. The trade-off is that your code is exposed for everyone to see (and steal). Generally, however, you aren’t doing amazingly s ophisticated things with scripting languages so this is not too much of a hardship.This points out that the scripting languages used inside Web browsers are really intended to solve specific types of problems, primarily the creation of richer and more interactive graphical user interfaces (GUIs). However, a scripting language might solve 80 percent of the problems encountered in client-side programming. Your problems might very well fit completely within that 80 percent, and since scripting languages can allow easier and faster development, you should probably consider a scripting language before looking at a more involved solution such as Java or ActiveX programming.The most commonly discussed browser scripting languages are JavaScript (which has nothing to do with Java; it’s named that way just to grab some of Java’s marketing momentum), VBScript (which looks like Visual Basic), andTcl/Tk, which comes from the popular cross-platform GUI-building language. There are others out there, and no doubt more in development.JavaScript is probably the most commonly supported. It comes built into both Netscape Navigator and the Microsoft Internet Explorer (IE). In addition, there are probably more JavaScript books available than there are for the other browser languages, and some tools automatically create pages using JavaScript. However, if you’re already fluent in Visual Basic or Tcl/Tk, you’ll be more productive using those scripting languages rather than learning a new one. (You’ll have your hands full dealing w ith the Web issues already.)4.JavaIf a scripting language can solve 80 percent of the client-side programming problems, what about the other 20 percent—the “really hard stuff?” The most popular solution today is Java. Not only is it a powerful programming language built to be secure, cross-platform, and international, but Java is being continually extended to provide language features and libraries that elegantly handle problems that are difficult in traditional programming languages, such as multithreading, database access, network programming, and distributed computing. Java allows client-side programming via the applet.An applet is a mini-program that will run only under a Web browser. The applet is downloaded automatically as part of a Web page (just as, for example, a graphic is automatically downloaded). When the applet is activated it executes a program. This is part of its beauty—it provides you with a way to automatically distribute the client software from the server at the time the user needs the client software, and no sooner. The user gets the latest version of the client software without fail and without difficult reinstallation. Because of the way Java is designed, the programmer needs to create only a single program, and that program automatically works with all computers that have browsers with built-in Java interpreters. (This safely includes the vast majority of machines.) Since Java is a full-fledged programming language, you can do as much work as possible on the client before and after making requests of theserver. For example, you won’t need to send a request form across the Internet to discover that you’ve gotten a date or some other parameter wrong, and your client computer can quickly do the work of plotting data instead of waiting for the server to make a plot and ship a graphic image back to you. Not only do you get the immediate win of speed and responsiveness, but the general network traffic and load on servers can be reduced, preventing the entire Internet from slowing down.On e advantage a Java applet has over a scripted program is that it’s in compiled form, so the source code isn’t available to the client. On the other hand, a Java applet can be decompiled without too much trouble, but hiding your code is often not an important issue. Two other factors can be important. As you will see later in this book, a compiled Java applet can comprise many modules and take multiple server “hits” (accesses) to download. (In Java 1.1 and higher this is minimized by Java archives, called JAR files, that allow all the required modules to be packaged together and compressed for a single download.) A scripted program will just be integrated into the Web page as part of its text (and will generally be smaller and reduce server hits). This could be important to the responsiveness of your Web site. Another factor is the all-important learning curve. Regardless of what you’ve heard, Java is not a trivial language to learn. If you’re a Visual Basic programmer, moving to VBScript will be your fastest solution, and since it will probably solve most typical client/server problems you might be hard pressed to justify learning Java. If you’re experienced with a scripting language you will certainly benefit from looking at JavaScript or VBScript before committing to Java, since they might fit your needs handily and you’ll be more productive sooner.to run its applets withi5.ActiveXTo some degree, the competitor to Java is Microsoft’s ActiveX, although it takes a completely different approach. ActiveX was originally a Windows-only solution, although it is now being developed via an independent consortium to become cross-platform. Effectively, ActiveX says “if your program connects toits environment just so, it can be dropped into a Web page and run under a b rowser that supports ActiveX.” (IE directly supports ActiveX and Netscape does so using a plug-in.) Thus, ActiveX does not constrain you to a particular language. If, for example, you’re already an experienced Windows programmer using a language such as C++, Visual Basic, or Borland’s Delphi, you can create ActiveX components with almost no changes to your programming knowledge. ActiveX also provides a path for the use of legacy code in your Web pages.6.SecurityAutomatically downloading and running programs across the Internet can sound like a virus-builder’s dream. ActiveX especially brings up the thorny issue of security in client-side programming. If you click on a Web site, you might automatically download any number of things along with the HTML page: GIF files, script code, compiled Java code, and ActiveX components. Some of these are benign; GIF files can’t do any harm, and scripting languages are generally limited in what they can do. Java was also designed to run its applets within a “sandbox” of s afety, which prevents it from writing to disk or accessing memory outside the sandbox.ActiveX is at the opposite end of the spectrum. Programming with ActiveX is like programming Windows—you can do anything you want. So if you click on a page that downloads an ActiveX component, that component might cause damage to the files on your disk. Of course, programs that you load onto your computer that are not restricted to running inside a Web browser can do the same thing. Viruses downloaded from Bulletin-Board Systems (BBSs) have long been a problem, but the speed of the Internet amplifies the difficulty.The solution seems to be “digital signatures,” whereby code is verified to show who the author is. This is based on the idea that a virus works because its creator can be anonymous, so if you remove the anonymity individuals will be forced to be responsible for their actions. This seems like a good plan because it allows programs to be much more functional, and I suspect it will eliminate malicious mischief. If, however, a program has an unintentional destructive bugit will still cause problems.The Java approach is to prevent these problems from occurring, via the sandbox. The Java interpreter that lives on your local Web browser examines the applet for any untoward instructions as the applet is being loaded. In particular, the applet cannot write files to disk or erase files (one of the mainstays of viruses). Applets are generally considered to be safe, and since this is essential for reliable client/server systems, any bugs in the Java language that allow viruses are rapidly repaired. (It’s worth noting that the browser software actually enforces these security restrictions, and some browsers allow you to select different security levels to provide varying degrees of access to your system.) You might be skeptical of this rather draconian restriction against writing files to your local disk. For example, you may want to build a local database or save data for later use offline. The initial vision seemed to be that eventually everyone would get online to do anything important, but that was soon seen to be impractical (although low-cost “Internet appliances” might someday satisfy the needs of a significant segment of users). The solution is the “signed applet” that uses public-key encryption to verify that an applet does indeed come from where it claims it does. A signed applet can still trash your disk, but the theory is that since you can now hold the applet creator accountable they won’t do vicious things. Java provides a framework for digital signatures so that you will eventually be able to allow an applet to step outside the sandbox if necessary. Digital signatures have missed an important issue, which is the speed that people move around on the Internet. If you download a buggy program and it does something untoward, how long will it be before you discover the damage? It could be days or even weeks. By then, how will you track down the program that’s done it? And what good will it do you at that point?7.Internet vs. intranetThe Web is the most general solution to the client/server problem, so it makes sense that you can use the same technology to solve a subset of the problem, in particular the classic client/server problem within a company. With traditionalclient/server approaches you have the problem of multiple types of client computers, as well as the difficulty of installing new client software, both of which are handily solved with Web browsers and client-side programming. When Web technology is used for an information network that is restricted to a particular company, it is referred to as an intranet. Intranets provide much greater security than the Internet, since you can physically control access to the servers within your company. In terms of training, it seems that once people understand the general concept of a browser it’s much easier for them to deal with differences in the way pages and applets look, so the learning curve for new kinds of systems seems to be reduced.The security problem brings us to one of the divisions that seems to be automatically forming in the world of client-side programming. If your program is running on the Internet, you don’t know what platform it will be working under, and you want to be extra careful that you don’t di sseminate buggy code. You need something cross-platform and secure, like a scripting language or Java.If you’re running on an intranet, you might have a different set of constraints. It’s not uncommon that your machines could all be Intel/Windows platfor ms. On an intranet, you’re responsible for the quality of your own code and can repair bugs when they’re discovered. In addition, you might already have a body of legacy code that you’ve been using in a more traditional client/server approach, whereby you must physically install client programs every time you do an upgrade. The time wasted in installing upgrades is the most compelling reason to move to browsers, because upgrades are invisible and automatic. If you are involved in such an intranet, the most sensible approach to take is the shortest path that allows you to use your existing code base, rather than trying to recode your programs in a new language.When faced with this bewildering array of solutions to the client-side programming problem, the best plan of attack is a cost-benefit analysis. Consider the constraints of your problem and what would be the shortest path to your solution. Since client-side programming is still programming, it’s always a good idea to take the fastest development approach for your particular situation.This is an aggressive stance to prepare for inevitable encounters with the problems of program development.8.Server-side programmingThis whole discussion has ignored the issue of server-side programming. What happens when you make a request of a server? Most of the time the request is simply “send me this file.” Your browser then interprets the file in some appropriate fashion: as an HTML page, a graphic image, a Java applet, a script program, etc. A more complicated request to a server generally involves a database transaction. A common scenario involves a request for a complex database search, which the server then formats into an HTML page and sends to you as the result. (Of course, if the client has more intelligence via Java or a scripting language, the raw data can be sent and formatted at the client end, which will be faster and less load on the server.) Or you might want to register your name in a database when you join a group or place an order, which will involve changes to that database. These database requests must be processed via some code on the server side, which is generally referred to as server-side programming. Traditionally, server-side programming has been performed using Perl and CGI scripts, but more sophisticated systems have been appearing. These include Java-based Web servers that allow you to perform all your server-side programming in Java by writing what are called servlets. Servlets and their offspring, JSPs, are two of the most compelling reasons that companies who develop Web sites are moving to Java, especially because they eliminate the problems of dealing with differently abled browsers.9. separate arena: applicationsMuch of the brouhaha over Java has been over applets. Java is actually a general-purpose programming language that can solve any type of problem—at least in theory. And as pointed out previously, there might be more effective ways to solve most client/server problems. When you move out of the appletarena (and simultaneously release the restrictions, such as the one against writing to disk) you enter the world of general-purpose applications that run standalone, without a Web browser, just like any ordinary program does. Here, Java’s strength is not only in its portability, but a lso its programmability. As you’ll see throughout this book, Java has many features that allow you to create robust programs in a shorter period than with previous programming languages. Be aware that this is a mixed blessing. You pay for the improvements through slower execution speed (although there is significant work going on in this area—JDK 1.3, in particular, introduces the so-called “hotspot” performance improvements). Like any language, Java has built-in limitations that might make it inappropriate to solve certain types of programming problems. Java is a rapidly evolving language, however, and as each new release comes out it becomes more and more attractive for solving larger sets of problems.Java和因特网既然Java不过另一种类型的程序设计语言，大家可能会奇怪它为什么值得如此重视，为什么还有这么多的人认为它是计算机程序设计的一个里程碑呢？如果您来自一个传统的程序设计背景，那么答案在刚开始的时候并不是很明显。

Java技术外文翻译文献

Java技术外文翻译文献(文档含中英文对照即英文原文和中文翻译)外文：Core Java™ Volume II–Advanced Features When Java technology first appeared on the scene, the excitement was not about a well-crafted programming language but about the possibility of safely executing applets that are delivered over the Internet (see V olume I, Chapter 10 for more information about applets). Obviously, delivering executable applets is practical only when the recipients are sure that the code can't wreak havoc on their machines. For this reason, security was and is a major concern of both the designers and the users of Java technology. This means that unlike other languages andsystems, where security was implemented as an afterthought or a reaction to break-ins, security mechanisms are an integral part of Java technology.Three mechanisms help ensure safety:•Language design features (bounds checking on arrays, no unchecked type conversions, no pointer arithmetic, and so on).•An access control mechanism that controls what the code can do (such as file access, network access, and so on).•Code signing, whereby code authors can use standard cryptographic algorithms to authenticate Java code. Then, the users of the code can determine exactly who created the code and whether the code has been altered after it was signed.Below, you'll see the cryptographic algorithms supplied in the java.security package, which allow for code signing and user authentication.As we said earlier, applets were what started the craze over the Java platform. In practice, people discovered that although they could write animated applets like the famous "nervous text" applet, applets could not do a whole lot of useful stuff in the JDK 1.0 security model. For example, because applets under JDK 1.0 were so closely supervised, they couldn't do much good on a corporate intranet, even though relatively little risk attaches to executing an applet from your company's secure intranet. It quickly became clear to Sun that for applets to become truly useful, it was important for users to be able to assign different levels of security, depending on where the applet originated. If an applet comes from a trusted supplier and it has not been tampered with, the user of that applet can then decide whether to give the applet more privileges.To give more trust to an applet, we need to know two things:•Where did the applet come from?•Was the code corrupted in transit?In the past 50 years, mathematicians and computer scientists have developed sophisticated algorithms for ensuring the integrity of data and for electronic signatures. The java.security package contains implementations of many of these algorithms. Fortunately, you don't need to understand the underlying mathematics to use the algorithms in the java.security package. In the next sections, we show you how message digests can detect changes in data files and how digital signatures can prove the identity of the signer.A message digest is a digital fingerprint of a block of data. For example, the so-called SHA1 (secure hash algorithm #1) condenses any data block, no matter how long, into a sequence of 160 bits (20 bytes). As with real fingerprints, one hopes that no two messages have the same SHA1 fingerprint. Of course, that cannot be true—there are only 2160 SHA1 fingerprints, so there must be some messages with the same fingerprint. But 2160is so large that the probability of duplication occurring is negligible. How negligible? According to James Walsh in True Odds: How Risks Affect Your Everyday Life (Merritt Publishing 1996), the chance that you will die from being struck by lightning is about one in 30,000. Now, think of nine other people, for example, your nine least favorite managers or professors. The chance that you and all of them will die from lightning strikes is higher than that of a forged message having the same SHA1 fingerprint as the original. (Of course, more than ten people, none of whom you are likely to know, will die from lightning strikes. However, we are talking about the far slimmer chance that your particular choice of people will be wiped out.)A message digest has two essential properties:•If one bit or several bits of the data are changed, then the message digest also changes.• A forger who is in possession of a given message cannot construct a fake message that has the same message digest as the original.The second property is again a matter of probabilities, of course. Consider the following message by the billionaire father:"Upon my death, my property shall be divided equally among my children; however, my son George shall receive nothing."That message has an SHA1 fingerprint of2D 8B 35 F3 BF 49 CD B1 94 04 E0 66 21 2B 5E 57 70 49 E1 7EThe distrustful father has deposited the message with one attorney and the fingerprint with another. Now, suppose George can bribe the lawyer holding the message. He wants to change the message so that Bill gets nothing. Of course, that changes the fingerprint to a completely different bit pattern:2A 33 0B 4B B3 FE CC 1C 9D 5C 01 A7 09 51 0B 49 AC 8F 98 92Can George find some other wording that matches the fingerprint? If he had been the proud owner of a billion computers from the time the Earth was formed, each computing a million messages a second, he would not yet have found a message he could substitute.A number of algorithms have been designed to compute these message digests. The two best-known are SHA1, the secure hash algorithm developed by the National Institute of Standards and Technology, and MD5, an algorithm invented by Ronald Rivest of MIT. Both algorithms scramble the bits of a message in ingenious ways. For details about these algorithms, see, for example, Cryptography and Network Security, 4th ed., by William Stallings (Prentice Hall 2005). Note that recently, subtle regularities have been discovered in both algorithms. At this point, most cryptographers recommend avoiding MD5 and using SHA1 until a stronger alternative becomes available.The Java programming language implements both SHA1 and MD5. The MessageDigest class is a factory for creating objects that encapsulate the fingerprinting algorithms. It has a static method, called getInstance, that returns an object of a class that extends the MessageDigest class. This means the MessageDigest class serves double duty:•As a factory class•As the superclass for all message digest algorithmsFor example, here is how you obtain an object that can compute SHA fingerprints:MessageDigest alg = MessageDigest.getInstance("SHA-1");(To get an object that can compute MD5, use the string "MD5" as the argument to getInstance.)After you have obtained a MessageDigest object, you feed it all the bytes in the message by repeatedly calling the update method. For example, the following code passes all bytes in a file to the alg object just created to do the fingerprinting：InputStream in = . . .int ch;while ((ch = in.read()) != -1)alg.update((byte) ch);Alternatively, if you have the bytes in an array, you can update the entire array at once:byte[] bytes = . . .;alg.update(bytes);When you are done, call the digest method. This method pads the input—as required by the fingerprinting algorithm—does the computation, and returns the digest as an array of bytes.byte[] hash = alg.digest();The program in Listing 9-15 computes a message digest, using either SHA or MD5. You can load the data to be digested from a file, or you can type a message in the text area.Message SigningIn the last section, you saw how to compute a message digest, a fingerprint for the original message. If the message is altered, then the fingerprint of the altered message will not match the fingerprint of the original. If the message and its fingerprint are delivered separately, then the recipient can check whether the message has been tampered with. However, if both the message and the fingerprint were intercepted, it is an easy matter to modify the message and then recompute the fingerprint. After all, the message digest algorithms are publicly known, and they don't require secret keys. In that case, the recipient of the forged message and the recomputed fingerprint would never know that the message has been altered. Digital signatures solve this problem.To help you understand how digital signatures work, we explain a few concepts from the field called public key cryptography. Public key cryptography is based on the notion of a public key and private key. The idea is that you tell everyone in the world your public key. However, only you hold the private key, and it is important that you safeguard it and don't release it to anyone else. The keys are matched by mathematical relationships, but the exact nature of these relationships is not important for us.The keys are quite long and complex. For example, here is a matching pair of public and private Digital Signature Algorithm (DSA) keys.Public key:Code View:p:fca682ce8e12caba26efccf7110e526db078b05edecbcd1eb4a208f3ae1617ae01f35b91a47e6df 63413c5e12ed0899bcd132acd50d99151bdc43ee737592e17q: 962eddcc369cba8ebb260ee6b6a126d9346e38c5g:678471b27a9cf44ee91a49c5147db1a9aaf244f05a434d6486931d2d14271b9e35030b71fd7 3da179069b32e2935630e1c2062354d0da20a6c416e50be794ca4y:c0b6e67b4ac098eb1a32c5f8c4c1f0e7e6fb9d832532e27d0bdab9ca2d2a8123ce5a8018b8161 a760480fadd040b927281ddb22cb9bc4df596d7de4d1b977d50Private key:Code View:p:fca682ce8e12caba26efccf7110e526db078b05edecbcd1eb4a208f3ae1617ae01f35b91a47e6df 63413c5e12ed0899bcd132acd50d99151bdc43ee737592e17q: 962eddcc369cba8ebb260ee6b6a126d9346e38c5g:678471b27a9cf44ee91a49c5147db1a9aaf244f05a434d6486931d2d14271b9e35030b71fd73 da179069b32e2935630e1c2062354d0da20a6c416e50be794ca4x: 146c09f881656cc6c51f27ea6c3a91b85ed1d70aIt is believed to be practically impossible to compute one key from the other. That is, even though everyone knows your public key, they can't compute your private key in your lifetime, no matter how many computing resources they have available.It might seem difficult to believe that nobody can compute the private key from the public keys, but nobody has ever found an algorithm to do this for the encryption algorithms that are in common use today. If the keys are sufficiently long, brute force—simply trying all possible keys—would require more computers than can be built from all the atoms in the solar system, crunching away for thousands of years. Of course, it is possible that someone could come up with algorithms for computing keys that are much more clever than brute force. For example, the RSA algorithm (the encryption algorithm invented by Rivest, Shamir, and Adleman) depends on the difficulty of factoring large numbers. For the last 20 years, many of the best mathematicians have tried to come up with good factoring algorithms, but so far with no success. For that reason, most cryptographers believe that keys with a "modulus" of 2,000 bits or more are currently completely safe from any attack. DSA is believed to be similarly secure.Figure 9-12 illustrates how the process works in practice.Suppose Alice wants to send Bob a message, and Bob wants to know this message came from Alice and not an impostor. Alice writes the message and then signs the message digest with her private key. Bob gets a copy of her public key. Bob then applies the public key to verify thesignature. If the verification passes, then Bob can be assured of two facts:•The original message has not been altered.•The message was signed by Alice, the holder of the private key that matches the public key that Bob used for verification.You can see why security for private keys is all-important. If someone steals Alice's private key or if a government can require her to turn it over, then she is in trouble. The thief or a government agent can impersonate her by sending messages, money transfer instructions, and so on, that others will believe came from Alice.The X.509 Certificate FormatTo take advantage of public key cryptography, the public keys must be distributed. One of the most common distribution formats is called X.509. Certificates in the X.509 format are widely used by VeriSign, Microsoft, Netscape, and many other companies, for signing e-mail messages, authenticating program code, and certifying many other kinds of data. The X.509 standard is part of the X.500 series of recommendations for a directory service by the international telephone standards body, the CCITT.The precise structure of X.509 certificates is described in a formal notation, called "abstract syntax notation #1" or ASN.1. Figure 9-13 shows the ASN.1 definition of version 3 of the X.509 format. The exact syntax is not important for us, but, as you can see, ASN.1 gives a precise definition of the structure of a certificate file. The basic encoding rules, or BER, and a variation, called distinguished encoding rules (DER) describe precisely how to save this structure in a binary file. That is, BER and DER describe how to encode integers, character strings, bit strings, and constructs such as SEQUENCE, CHOICE, and OPTIONAL.译文：Java核心技术卷Ⅱ高级特性当Java技术刚刚问世时，令人激动的并不是因为它是一个设计完美的编程语言，而是因为它能够安全地运行通过因特网传播的各种applet。

(完整word版)JAVA外文文献+翻译

Java and the InternetIf Java is, in fact， yet another computer programming language， you may question why it is so important and why it is being promoted as a revolutionary step in computer programming. The answer isn't immediately obvious if you’re comin g from a traditional programming perspective. Although Java is very useful for solving traditional stand—alone programming problems, it is also important because it will solve programming problems on the World Wide Web。

1.Client—side programmingThe Web’s in itial server—browser design provided for interactive content， but the interactivity was completely provided by the server. The server produced static pages for the client browser, which would simply interpret and display them。

Basic HTML contains simple mechanisms for data gathering: text-entry boxes， check boxes, radio boxes， lists and drop—down lists, as well as a button that can only be programmed to reset the data on the form or “submit” the data on the form back to the server。

java毕业设计外文文献原文及译文

英文文献及中文翻译Thinking in JavaAlthough it is based on C++, Java is more of a “pure” object-oriented language.Both C++ and Java are hybrid languages, but in Java the designers felt that the hybridization was not as important as it was in C++. A hybrid language allows multiple programming styles; the reason C++ is hybrid is to support backward compatibility with the C language. Because C++ is a superset of the C language, it includes many of that language’s undesirable features, which can make some aspects of C++ overly complicated. The Java language assumes that you want to do only object-oriented programming. This means that before you can begin you must shift your mindset into an object-oriented world (unless it’s already there). The benefit of this initial effort is the ability to program in a language that is simpler to learn and to use than many other OOP languages. In this chapter we’ll see the basic components of a Java program and we’ll learn that everything in Java is an object, even a Java program.Each programming language has its own means of manipulating data. Sometimes the programmer must be constantly aware of what type of manipulation is going on. Are you manipulating the object directly, or are you dealing with some kind of indirect representation (a pointer in C or C++) that must be treated with a special syntax?All this is simplified in Java. You treat everything as an object, using a single consistent syntax. Although you treat everything as an object, the identifier you manipulate is actually a “reference” to an object. You might imagine this scene as a television (the object) with your remote control (the reference). As long as you’re holding this reference, you have a connection to the television, but when someone says “change the channel” or “lower the volume,” what you’re manipulating is the reference, which in turn modifies the object. If you want to move around the room and still control the television, you take the remote/reference with you, not the television.Also, the remote control can stand on its own, with no television. That is, just because you have a reference doesn’t mean there’s necessarily an object connected to it. So if you want to hold a word or sentence, you create a String reference:But here you’ve created only the reference, not an object. If you decided to send a message to s at this point, you’ll get an error (at run time) because s isn’t actually attached to anything (there’s no television). A safer practice, then, is always to initialize a reference when you create it.However, this uses a special Java feature: strings can be initialized with quoted text. Normally, you must use a more general type of initialization for objectsWhen you create a reference, you want to connect it with a new object. You do so, in general, with the new keyword. The keyword new says, “Make me a new one of these objects.” So in the preceding example, you can say:Not only does this mean “Make me a new String,” but it also gives information about how to make the String by supplying an initial character string.Of course, String is not the only type that exists. Java comes with a plethora of ready-made types. What’s more important is that you can create your own types. In fact, that’s the fundamental activity in Java programming, and it’s what you’ll be learning about in the rest of this bookIt’s useful to visualize some aspects of how things are laid out while the program is running—in particular how memory is arranged. There are six different places to store data: Registers. This is the fastest storage because it exists in a place different from that of other storage: inside the processor. However, the number of registers is severely limited, so registers are allocated by the compiler according to its needs. You don’t have direct contr ol, nor do you see any evidence in your programs that registers even exist.The stack. This lives in the general random-access memory (RAM) area, but has direct support from the processor via its stack pointer. The stack pointer is moved down to create new memory and moved up to release that memory. This is an extremely fast and efficient way to allocate storage, second only to registers. The Java compiler must know, while it is creating the program, the exact size and lifetime of all the data that is stored on the stack, because it must generate the code to move the stack pointer up and down. This constraint places limits on the flexibility of your programs, so while some Java storage exists on the stack—in particular, object references—Java objects themselves are not placed on the stack. The heap. This is a general-purpose pool of memory (also in the RAM area) where all Java objects live. The nice thing about the heap is that, unlike the stack, the compiler doesn’t needto know how much storage it needs to allocate from the heap or how long that storage must stay on the heap. Thus, there’s a great deal of flexibility in using storage on the heap. Whenever you need to create an object, you simply write the code to create it by using new, and the storage is allocated on the heap when that code is executed. Of course there’s a price you pay for this flexibility. It takes more time to allocate heap storage than it does to allocate stack storage (if you even could create objects on the stack in Java, as you can in C++). Static storage. “Static” is used here in the sense of “in a fixed location” (although it’s also in RAM). Static storage contains data that is available for the entire time a program is running. You can use the static keyword to specify that a particular element of an object is static, but Java objects themselves are never placed in static storage.Constant storage. Constant values are often placed directly in the program code, which is safe since they can never change. Sometimes constants are cordoned off by themselves so that they can be optionally placed in read-only memory (ROM), in embedded systems.Non-RAM storage. If data lives completely outside a program, it can exist while the program is not running, outside the control of the program. The two primary examples of this are streamed objects, in which objects are turned into streams of bytes, generally to be sent to another machine, and persistent objects, in which the objects are placed on disk so they will hold their state even when the program is terminated. The trick with these types of storage is turning the objects into something that can exist on the other medium, and yet can be resurrected into a regular RAM-based object when necessary. Java provides support for lightweight persistence, and future versions of Java might provide more complete solutions for persistenceOne group of types, which you’ll use quite often in your programming, gets special treatment. You can think of these as “primitive” types. The reason for the special trea tment is that to create an object with new—especially a small, simple variable—isn’t very efficient, because new places objects on the heap. For these types Java falls back on the approach taken by C and C++. That is, instead of creating the variable by using new, an “automatic” variable is created that is not a reference. The variable holds the value, and it’s placed on the stack, so it’s much more efficient.Java determines the size of each primitive type. These sizes don’t change from one machine architecture to another as they do in most languages. This size invariance is one reason Java programs are portableJava编程思想“尽管以C++为基础，但Java是一种更纯粹的面向对象程序设计语言”。

JAVA学习过程论文中英文资料对照外文翻译文献

JAVA学习过程论文中英文资料对照外文翻译文献During my process of learning Java。

I have found that everyone has their own unique study method。

What works for one person may not work for another。

As I am studying Java independently。

I have not asked ___。

I have had to rely on my own ___ out。

While I cannot say whether this is the best method。

I can offer it as a reference for others.When I first started learning Java。

___ understanding of the language。

As I progressed。

I began to work on small projects to apply what I had learned.One of the biggest challenges I faced was understanding object-oriented programming。

___。

once I understood the basics。

everything else started to fall into place.___ practicing programming。

I also made sure to take breaks and give my brain time to rest。

I found that this helped me to ___.Overall。

my learning process has been a n of n。

Java毕设论文英文翻译

Java毕设论文英文翻译Java and the InternetIf Java is, in fact, yet another computer programming language, you mayquestion why it is so important and why it is being promoted as a revolutionarystep in computer programming. The answer isn’ｔimmediately obvious if you’re coming from a traditional programming perspective. Although Java is very useful for solving traditional standalone programming problems, it is also important because it will solve programming problems on the World Wide Web.What is the Web?The Web can seem a bit of a mystery at first, with all this talk of “surfing,”helpful to step back and see what it realland “homepages.”It’ｓ“presence,”y is, but to do this you must understand client/server systems, another aspecfull of confusing issues.t of computing that’ｓClient/Se rver computingThe primary idea of a client/server system is that you have a central repositoryof information—some kind of data, often in a database—that you want todistribute on demand to some set of people or machines. A key to the client/server concept is that the repository of information is centrally located so that it an be changed and so that those changes will propagate out to the information consumers. Taken together, the information repository, the software that distributes the information, and the machine(s) where the information and software reside is called the server. The software that resides on the remote machine, communicates with the server, fetches the information, processes it, and then displays it on the remote machine is called the client.The basic concept of client/server computing, then, is not so complicated. The problems arise because you have a single server trying to serve many clientsat once. Generally, a database management system is involved, so the designer the layout of data into tables for optimal use. In addition, systems oft “balances”en allow a client to insert new information into a server. This means you mustnew datwalk over another client’ｓnew data doesn’ｔensure that one cl ient’ｓlost in the process of adding it to the database (this is called a, or that data isn’ｔtransaction processing). As client software changes, it mustbe built, debugged,and installed on the client machines, which turns out to be more complicatedespecially problematic to support muand expensive than you might think. It’ｓthe all-impoltiple types of computers and operating systems. Finally, there’ｓrtant performance issue: You might have hundreds of clients making requestsof your server at any one time, so any small delay is crucial. To minimize latency, programmers work hard to offload processing tasks, often to the client machine, but sometimes to other machines at the server site, using so-called middleware. (Middleware is also used to improve maintainability.)The simple idea of distributing information has so many layers of complexitcrucial: Cliy that the whole problem can seem hopelessly enigmatic. And yet it’ｓent/server computing accounts for roughly half of all programming activities. It’s responsible for everything from taking orders and credit-c ar d transactions tothe distribution of any kind of data—stock market, scientific, government, youname it. What we’ve come up with in the past is individual solutions to individual problems, inventing a new solution each time. These were hard to create and hard to use, and the user had to learn a new interface for each one. The entire client/server problem needs to be solved in a big way.The Web asagiant s ervera bit worse than thThe Web is actually one giant client/server system. It’ｓat, since you have all the servers and clients coexisting on a single network atneed to know that, because all you care about is connecting to a once. You don’ｔnd interacting with one server at a time (even though you might be hopping around the world in your search for the correct server). Initially it was a simple one-way process. You made a request of a server and it handed you a file, which y browser software (i.e., the client) would interpret by formatting o our machine’ｓnto your local machine. But in short order people began wanting to do morethan just deliver pages from a server. They wanted full client/server capability so that the client could feed information back to the server, for example, to do database lookups on the server, to add new information to the server, or to place an order ( which required more security than the original systems offered). These are thechanges we’ve been seeing in the development of the Web.The Web browser was a big step forward: the concept that one piece of information could be displayed on any type of computer without change. However, br owsers were still rather primitive and rapidly bogged down by the demands plaparticularly interactive, and tended to clog up bothced on them. They weren’ｔthe server and the Internet because any time you needed to do something that required programming you had to send information back to the server to be pro cessed. It could take many seconds or minutes to find out you had misspelled perf something in your request. Since the browser was just a viewer it couldn’ｔorm even the simplest computing tasks. (On the otherexecute any programs on your local machi hand, it was safe, because it couldn’ｔne that might contain bugs or viruses.)To solve this problem, different approaches have been taken. To begin with, gr aphics standards have been enhanced to allow better animation and video within browsers. The remainder of the problem can be solved only by incorporating the ability to run programs on the client end, under the browser. This iscalled client-side programming.Client-side programmingThe Web’ｓinitial server-browser design provided for interactive content, but the interactivity was completely provided by the server. The server produced static pages for the client browser, which would simply interpret and display them. Basic HyperText Markup Language (HTML) contains simple mechanis ms for data gathering: text-entry boxes, check boxes, radio boxes, lists and drop-down lists, as well as a button that can only be programmed to reset the dataon the form or “submit”the data on the form back to the server. This submissio n passes through the Common Gateway Interface (CGI) provided on all Web servers. The text within the submission tells CGI what to do with it. The most common action is to run a program located on the server in a directory th typically called “cgi-b in.” (If you watch the address window at the top ofat’ｓyour browser when you push a button on a Web page, you can sometimes see “cgi-bin” within all the gobbledygook there.) These programs can be written in most languages. Perl has been a common choice because it is designed for text manipulation and is interpreted, so it can be installed on any server regardlessof processor or operating system. However, Python (my favorite—see www.Pyt /doc/4110905303.html,) has been making inroads because of its greater power and simplicity. Many powerful Web sites today are built strictly on CGI, and you can in fact do nearly anything with CGI. However, Web sites built on CGI programs can rapidly become overly complicated to maintain, and there is alsothe problem of respo nse time. The response of a CGI program depends on how much data must be s ent, as well as the load on both the server and the Internet. (On top of this, sta rting a CGI program tends to be slow.) The initial designers of the Web did notforesee how rapidly this bandwidth would be exhausted for the kinds of applic ations people developed. For example, any sort of dynamic graphing is nearly i mpossible to perform with consistency because a Graphics Interchange Format (GIF) file must be created and moved from the server to the client for each ve rsion of the graph. And you’ve no doubt had direct experience with somethingas simple as validating the data on an input form. You press the submit button on a page; the data is shipped back to the server; the server starts a CGI pro gram that discovers an error, formats an HTML page informing you of the error, and then sends the page back to you; you minelegant. The so ust then back up a page and try again. Not only is this slow, it’ｓlution is client-side programming. Most machines that run Web browsers are powerful engines capable of doing vast work, and with the original static HTML approach they are sitting there, just idly waiting for the server to dish up thenext page. Client-side programming means that the Web browser is harnessedto do whatever work it can, and the result for the user is a much speedier andmore interactive experience at your Web site. The problemwith discussionsvery different from discussionsof client-side programmi ng is that they aren’ｔof programming in general. The parameters are almost the same, but the platform is different; a Web browser is like a limited operating system. In the end,you must still program, and this accounts for the dizzying array of problems and solutions produced by client-side programming. The rest of this section pro vides an overview of the issues and approaches in client-side programming.Plug-insOne of the most significant steps forward in client-side programming is the development of the plug-in. This is a way for a programmer to add new funct ionality to the browser by downloading a piece of code that plugs itself into the appropriate spot in the browser. It tells the browser “from now on you can perf (You need to download the plug-in only once.) Some fast orm this new activity.”and powerful behavior is added to browsers via plug-ins, but writing a plug-inwant to do as part ofsomething you’ｄis not a trivial task, and isn’ｔthe process of building a particular site. The value of the plug-in for client-side programming is that it allows an expert programmer todevelop a new language and add that language to a browser without the permission of the browser manufacturer. Thus, plug-ins provide a “back d oor” that allows the creation of new client-side programming languages (although not all languages are implemented as plug-ins).ScriptinglanguagesPlug-ins resulted in an explosion of scripting languages. With a scripting language, you embed the source code for your client-side program directlyinto the HTML page, and the plug-in that interprets that language is automatically activated while the HTML page is being displayed. Scripting languages tend to be reasonably easy to understand and, because they are simply text that is part of an HTML page, they load very quickly as part of the single server hit required to procure that page. The trade-off is that your code is exposed fordoing amazingly so everyone to see (and steal). Generally, however, you aren’ｔphisticated things with scripting languages, so this is not too much of a hardship.This points out that the scripting languages used inside Web browsers are really intended to solve specific types of problems, primarily the creation of richerand more interactive graphical user interfaces (GUIs).However, a scripting language might solve 80 percent of the problems encountered in client-side prog ramming. Your problems might very well fit completely within that 80 percent,and since scripting languages can allow easier and faster development, you should probably consider a scripting language before looking at a more involved s olution such as Java or ActiveX programming.The most commonly discussed browser scripting languages are JavaScript (named that way just to grab some of Ja which has nothing to do with Java; it’ｓmarketing momentum), VBScript (which looks like Visual BASIC), and Tcl/va’ｓTk, which comes from the popular cross-platform GUI-building language. There are others out there, and no doubt more in development.JavaScript is probably the most commonly supported. It comes built into bothNetscape Navigator and the Microsoft Internet Explorer (IE). Unfortunately,the flavor of JavaScript on the two browsers can vary widely (the Mozilla browser, freely downloadable from /doc/4110905303.html,, supports the ECMAScript standard, which may one day become universally supported). In addition, there are probably more JavaScript books available than there arefor the other browser languages, and some tools automatically create pages using JavaScript. However, if you’re already fluent in Visual BASIC or Tcl/Tk, you’ll be more pr oductive using those scripting languages rather than learning a new one. (You’ｌl have your hands full dealing with the Web issues already.)ja va和因特网既然Jav a不过另一种类型的程序设计语言，大家可能会奇怪它为什么值得如此重视，为什么还有这么多的人认为它是计算机程序设计的一个里程碑呢？如果您来自一个传统的程序设计背景，那么答案在刚开始的时候并不是很明显。

Java编程语言基础(外文文献翻译)(可编辑)

JavaTM Programming Language BasicsLike applications, applets are created from classes. However, applets do not have a main method as an entry point, but instead, have several methods to control specific aspects of applet execution.This lesson converts an application from Lesson 2 to an applet and describes the structure and elements of an applet.1、Application to Applet2、Run the Applet3、Applet Structure and Elements4、Packages5、More Information1、Application to AppletThe following code is the applet equivalent to the LessonTwoB application from Lesson 2. The figure below shows how the running applet looks. The structure and elements of the applet code are discussed after the section on how to run the applet just below.import et;import hics;import r;public class SimpleApplet extends AppletString text "I'm a simple applet";public void inittext "I'm a simple applet";setBackground Color.cyan ;public void startSytln "starting..." ;public void stopSytln "stopping..." ;public void destroySytln "preparing to unload..." ;public void paint Graphics gSytln "Paint" ;g.setColor Color.blue ;g.drawRect 0, 0,getSize .width -1,getSize .height -1 ;g.setColor Color.red ;g.drawString text, 15, 25 ;The SimpleApplet class is declared public so the program that runs the applet a browser or appletviewer , which is not local to the program can access it.2、Run the AppletTo see the applet in action, you need an 6>HTML file with the Applet tag as follows:APPLET CODE SimpleApplet.class WIDTH 200 HEIGHT 100The easiest way to run the applet is with appletviewer shown below where simpleApplet.html is a file that contains the above HTML code:appletviewer simpleApplet.htmlNote: To run an applet written with JavaTM 2 APIs in a browser, the browser must be enabled for the Java 2 Platform. If your browser is not enabled for the Java 2 Platform, you have to use appletviewer to run the applet or install Java Plug-in. Java Plug-in lets you run applets on web pages under the 1.2 version of the Java VM instead of the web browser's default Java VM.3、Applet Structure and ElementsThe Java API Applet class provides what you need to design the appearance and manage the behavior of an applet. This class provides a graphical user interface GUI component called a Panel and a number of methods. To create an applet, you extend or subclass the Applet class and implement the appearance and behavior you want.The applet's appearance is created by drawing onto the Panel or by attaching other GUI components such as push buttons, scrollbars, or text areas to the Panel. The applet's behavior is defined by implementing the methods.3.1 Extending a ClassMost classes of any complexity extend other classes. To extend another class means to write a new class that can use the fields and methods defined in the class being extended. The class being extended is the parent class, and the class doing the extending is the child class. Another way to say this is the child class inherits the fields and methods of its parent or chain of parents. Child classes either call or override inherited methods. This is called single inheritance.The SimpleApplet class extends Applet class, which extends the Panel class, which extends the Container class. The Container class extends Object, which is the parent of all Java API classes. The Applet class provides the init, start, stop, destroy, and paint methods you saw in the example applet. The SimpleApplet class overrides these methods to do what the SimpleApplet class needs them to do. The Applet class provides no functionality for these methods.However, the Applet class does provide functionality for the setBackground method,which is called in the init method. The call to setBackground is an example of calling a method inherited from a parent class in contrast to overriding a method inherited from a parent class.You might wonder why the Java language provides methods without implementations. It is to provide conventions for everyone to use for consistency across Java APIs. If everyone wrote their own method to start an applet, for example, but gave it a different name such as begin or go, the applet code would not be interoperable with other programs and browsers, or portable acrossmultiple platforms. For example, Netscape and Internet Explorer know how to look for the init and start methods.3.2 BehaviorAn applet is controlled by the software that runs it. Usually, the underlying software is a browser, but it can also be appletviewer as you saw in the example. The underlying software controls the applet by calling the methods the applet inherits from the Applet class.The init Method: The init method is called when the applet is first created and loaded by the underlying software. This method performs one-time operations the applet needs for its operation such as creating the user interface or setting the font. In the example, the init method initializes the text string and sets the background color.The start Method: The start method is called when the applet is visited such as when the end user goes to a web page with an applet on it. The example prints a string to the console to tell you the applet is starting. In a more complex applet, the start method would do things required at the start of the applet such as begin animation or play sounds.After the start method executes, the event thread calls the paint method to draw to the applet's Panel. A thread is a single sequential flow of control within the applet, and every applet can run in multiple threads. Applet drawing methods are always called from a dedicated drawing and event-handling thread.The stop and destroy Methods: The stop method stops the applet when the applet is no longer on the screen such as when the end user goes to another web page. The example prints a string to the console to tell you the applet is stopping. In a more complex applet, this method should do things like stop animation or sounds.The destroy method is called when the browser exits. Your applet should implement this method to do final cleanup such as stop live threads.3.3 AppearanceThe Panel provided in the Applet class inherits a paint method from its parent Container class. To draw something onto the Applet's Panel, you implement the paint method to do the drawing. The Graphics object passed to the paint method defines a graphics context for drawing on the Panel. The Graphics object has methods for graphical operations such as setting drawing colors, and drawing graphics, images, and text.The paint method for the SimpleApplet draws the I'm a simple applet string in red inside a blue rectangle.public void paint Graphics gSytln "Paint" ;//Set drawing color to blueg.setColor Color.blue ;//Specify the x, y, width and height for a rectangleg.drawRect 0, 0,getSize .width -1,getSize .height -1 ;//Set drawing color to redg.setColor Color.red ;//Draw the text string at the 15, 25 x-y locationg.drawString text, 15, 25 ;4、PackagesThe applet code also has three import statements at the top. Applications of any size and all applets use import statements to access ready-made Java API classes in packages. This is true whether the Java API classes come in the Java platform download, from a third-party, or are classes you write yourself and store in a directory separate from the program. At compile time, a program uses import statements to locate and reference compiled Java API classes stored in packages elsewhere on the local or networked system. A compiled class in one package can have the same name as a compiled class in another package. The package name differentiates the two classes.The examples in Lessons 1 and 2 did not need a package declaration to call the Sytln Java API class because the System class is in the ng package that is included by default. You never need an import ng.* statement to use the compiled classes in that package.5、More InformationYou can find more information on applets in the Writing Applets trail in The Java Tutorial.文献译文Java 编程语言基础像Java Application小应用程序一样，Java Applet小程序也是从类中创建来的。

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JAVA学习过程论文中英文资料对照外文翻译文献Java Learning Path processEach person's study method is different, a person's method suits another person not necessarily, I only can discuss own study method. Because I study Java am study independently completely, has not asked others, therefore the study process basically is completely oneself tries to find out. I did not know whether this method is the quite good method, only could give everybody to provide refers.Studies Java first step installs good JDK, writes Hello World? Actually the JDK study is not so simple, has two questions about JDK is very easy to puzzle the Java programmer continuously the place: Is the CLASSPATH question, actually said from the principle, is how must make clear JRE ClassLoader increase Class; Another question is package and the import question, how seeks the kind of way question. These two questions tried to find out clear, eliminated has studied Java and uses JDK the biggest barrier. The recommendation looked Wang Sen "the Java Depth Experiences dangers", has carried on the thorough discussion to these two questionsSecond step is studies Java the grammar. The Java grammar is kind of C++, the basically mainstream programming language is not kind of C, is kind of C++, does not have what new thing, therefore the grammar study, probably was the quite a while time is enough. Only needs to pay attention is has the key words usage which several is not easy to make clear, public, protected, private, static, when uses, why has to use, how uses, this possible need some people to direct, I initially was own ponder over completely, has spent the very long time. But afterwards I saw above this book spoke these concepts to "Thinking in Java".Third step is studies Java the object-oriented programming language characteristic place. For instance inherits, structure, abstract class, the connection, the method are many condition, heavy load, cover, Java exception handling mechanism. Said regarding a not object-oriented language background person that, I thought this process needs to spend the very long very long time, because studies in front of Java does not have C++ the experience, only then the C experience, I was have probably spent for a month, all made clear only then thoroughly these concepts, book example above repeatedly estimating, the revision, the attempt, repeatedly looked at that several chapter of contents, looked, looked has not gotten down 5, comprehended only then thoroughly. But I thought if has the C++ experience, should 12 days time be enough. Then in this process, may have a look "Thinking in Java" this book, opposite is extremely thorough to the object explanation. What a pity is I studies, has not seen to this book, therefore own have spent the massive time, and estimates through own attempt learns.Fourth step starts a familiar Java kind of storehouse. The Java foundation class storehouse actually is JDK installs under the table of contentsjre\Lib\Rt.Jar this package. The study foundation class storehouse studies rt.Jar. Inside the foundation class storehouse kind are extremely extremely many. It is said some more than 3,000, I have not counted. But said the most core truly regarding us only then 4, respectively isng.*;Java.Io.*;Java.Util.*;Java.Sql.*;These four packages study, each package study all may write thick teaching material, but O'reilly also truly is does this. I thought if time quite tight, is impossible through to read four books to study. I thought the quite good study method is such:First must read through entire package the frame, understood entire package class, interface, the exception constitution, should better be can find the introduction entire package frame the article. These introduced specially package of books the first several chapters should be these overall frame content introductions. Is not must be familiar with each kind of usage to the package of overall frame assurance, which attributes remembers it have, the method. Wants to record also cannot remember. But is must know which aspects the package does have a kind of constitution, these kind of uses are any, most core several classifications maybe complete any function. I in the time which trains to the human generally is a class speaks a package, therefore not impossible detailed introduction each kind of usage, but I repeatedly stress, how do I speak these packages to you am must tell you a kind of method am transfer, also does not request you to remember the kind of method transfer, but wants you tounderstand, which kinds Java has provided to us, each kind is uses in any situation, when I meet the question the time, I knew which kind, or which several kind of combinations can solve my problem, That'all! When we write the procedure specifically time, so long as you knew which kind should complete your work with to be enough. Codes, the concrete method transfer, writes the code, Documentation, all things all inside Documentation, will not request you certainly to remember, are actual you also not to be able to remember more than 3,000 kinds altogether the nearly 100,000 methods transfers. Therefore changes to each package overall frame assurance extremely importantly.Fifth step, through above study, if study the quite solid speech, built the Java foundation, is left over the work which had to do is sweeps clean inside Documentation besides above 4 packages other some comparisons to have the use the kind. Believed progressed to this step, Java studies independently the ability already to raise, might to study Documentation directly horizontal. Besides must make the GUI programming, inside JDK other can have the use the package is these:Java.Text.*;.*;Javax.Naming.*;These packages of inside real correct uses quite many kinds very are actually few, only then several, therefore does not need to spend the very much time.Sixth step, Java Web programmingThe Web programming core is the HTTP agreement, the HTTP agreement and Java irrelevant, if not familiar HTTP agreement, although also may learnServlet/JSP programming, but cannot achieve extrapolates, by knowing one method you will know all boundary. Therefore the HTTP agreement study is necessary. If has been familiar with HTTP agreement, also had the Java programming good foundation, studies Servlet/JSP is simply easy as pie, I study Servlet/JSP has used not to week-long time, then started with JSP to make the project. In Servlet/In the JSP study, heavy still was Servlet Documentation. Servlet the API most commonly used kind are very few, the flowered quite few time might grasp. These kinds all looked at, writes several examples to try. Servlet/The JSP programming essence is transferring these kinds to come repeatedly through the HTTP agreement converses between Web Server and Brower. Moreover to JSP, but also needs to be familiar with several commonly used JSP the mark, the concrete mode of writing cannot remember the speech, looks up temporarily and that's the end of.In addition Java the Web programming study must place Web Application with emphasis in the design pattern, how carries on the service logic the analysis, and carries on the reasonable design, according to the MVC design pattern request, completes the different logical level separately using Servlet and JSP, how grasps carries on the flow between Servlet and JSP the control and data sharing, as well as how Web should Application dispose and the deployment.Seventh step, J2EE programmingThe above study process if is quite smooth, carries on to this step, the difficulty enhances suddenly. Because the above knowledge content all only involves an aspect, but likes EJB, JMS, core the and so on JTA J2EE standard often is several kind of Java technology synthesis utilization crystallization, therefore grasps the difficulty quite to be big.First certainly must study good JNDI, JNDI is App the Server localization server resources (the EJB module, Datasouce, JMS) searches the method, if to JNDI not familiar, EJB, JMS these things cannot study nearly. JNDI actually is javax.Naming.* This package, utilizes is very simple. The difficulty lies in the server resources document the disposition. Regarding the server resources document disposition, needed to have a look the special documents to be standard, for instance web.Xml mode of writing, ejb-jar.Xml mode of writing and so on. In view of each kind of different App Server, but also has own service resources disposition document, also is needs to be familiar with.Then may study JTA, mainly is must understand JTA regarding business control method, as well as should use JTA in any situation. Here may simple cite an example, we knew the ordinary circumstances may carry on business regarding a database connection (conn.SetAutoCommit (false)....,mit ()), does is an atomic operation, but the supposition my service demand is needs to hold artificially to two different databases is an atomic operation, you can do to? At this time only could use JTA. The supposition operating process inserts a record first toward the A database, then deletes the B database another record, we wrote the code are cannot control entire hold artificially are an atomic operation. With the JTA speech, completes the control by App Server.In studies in front of EJB must study the object sequence and RMI, RMI is the EJB foundation. Then studies JMS and EJB, said regarding EJB, most is essential is must understand how EJB is realizes through RMI to the far-end object transfer, as well as must use in any situation to EJB.In studies EJB, after JMS these things, you possibly can realize must extremely anxiously study two domains the knowledge, is UML, another isDesign Pattern. The Java enterprise software design takes the frame extremely (Framework) the design, a good software frame is the software develops the successful essential condition. In this time, should start the study key point to place the design pattern and in the frame study, experiences through the study and the actual programming grasps EJB the design pattern and the J2EE core pattern.Inside J2EE standard, except EJB, JMS, JTA, Servlet/JSP, outside JDBC also has the very many very many enterprises technology, here 11 did not carry on introducedMoreover also has newest domain Web Services. Web Services also completely does not have any new thing, it likes is one kind of adhesive, may unify the different service provides a unified transfer connection, said as the user, I so long as obtain the service provider for mine WSDL (to service description), has sufficed, I did not know completely the server tenderer provides actually the service is the EJB module,The Net module, any CORBA module, other any realizations, I do not need to know. Web the Services greatest place lies in through the unified service provides the way and the transfer way, has realized the entire Internet service sharing, is an extremely excited area of technology. Web Services resembles at present not to have any very good books, but may through look up the material above the network the way to study.JA V A学习过程每个人的学习方法是不同的，一个人的方法不见得适合另一个人，我只能是谈自己的学习方法。

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