JAVA学习过程毕业论文外文翻译.doc

附录4 外文原文外文原文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 contents jreLibRt.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 is Java.Lang.*; 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 to understand, 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.*; Java.Net.*; 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 programming The Web programming core is the HTTP agreement, the HTTP agreement and Java irrelevant, if not familiar HTTP agreement, although also may learn Servlet/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 programming The 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).,Conn.Commit (), 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 is Design 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.附录5 外文译文JAVA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。因为我学习Java是完全自学的，从来没有问过别人，所以学习的过程基本上完全是自己摸索出来的。我也不知道这种方法是否是比较好的方法，只能给大家提供一点参考了。 学习Java的第一步是安装好JDK，写一个Hello World，其实JDK的学习没有那么简单，关于JDK有两个问题是很容易一直困扰Java程序员的地方：一个是CLASSPATH的问题，其实从原理上来说，是要搞清楚JRE的ClassLoader是如何加载Class的；另一个问题是package和import问题，如何来寻找类的路径问题。把这两个问题摸索清楚了，就扫除了学习Java和使用JDK的最大障碍。推荐看一下王森的Java深度历险，对这两个问题进行了深入的探讨。 第二步是学习Java的语法。Java的语法是类C+的，基本上主流的编程语言不是类C，就是类C+的，没有什么新东西，所以语法的学习，大概就是半天的时间足够了。唯一需要注意的是有几个不容易搞清楚的关键字的用法，public，protected，private，static，什么时候用，为什么要用，怎么用，这可能需要有人来指点一下，我当初是完全自己琢磨出来的，花了很久的时间。不过后来我看到Thinking in Java这本书上面是讲了这些概念的。 第三步是学习Java的面向对象的编程语言的特性的地方。比如继承，构造器，抽象类，接口，方法的多态，重载，覆盖，Java的异常处理机制。对于一个没有面向对象语言背景的人来说，我觉得这个过程需要花很长很长时间，因为学习Java之前没有C+的经验，只有C的经验，我是大概花了一个月左右吧，才彻底把这些概念都搞清楚，把书上面的例子反复的揣摩，修改，尝试，把那几章内容反复的看过来，看过去，看了不下5遍，才彻底领悟了。不过我想如果有C+经验的话，应该一两天时间足够了。那么在这个过程中，可以多看看Thinking in Java这本书，对面向对象的讲解非常透彻。可惜的是我学习的时候，并没有看到这本书，所以自己花了大量的时间，通过自己的尝试和揣摩来学会的。 第四步就是开始熟悉Java的类库。Java的基础类库其实就是JDK安装目录下面jrelibrt.jar这个包。学习基础类库就是学习rt.jar。基础类库里面的类非常非常多。据说有3000多个，我没有统计过。但是真正对于我们来说最核心的只有4个，分别是:java.lang.*;java.io.*;java.util.*; java.sql.*;这四个包的学习，每个包的学习都可以写成一本厚厚的教材，而O'reilly也确实是这样做的。我觉得如果时间比较紧，是不可能通过读四本书来学习。我觉得比较好的学习方法是这样的：首先要通读整个package的框架，了解整个package的class，interface，exception的构成，最好是能够找到介绍整个包框架的文章。这些专门介绍包的书籍的前几章应该就是这些总体的框架内容介绍。对包整体框架的把握并不是要熟悉每个类的用法，记住它有哪些属性，方法。想记也记不住的。而是要知道包有哪些方面的类构成的，这些类的用途是什么，最核心的几个类分别是完成什么功能的。我在给人培训的时候一般是一次课讲一个包，所以不可能详细的介绍每个类的用法，但是我反复强调，我给你们讲这些包的不是要告诉你们类的方法是怎么调用的，也不要求你们记住类的方法调用，而是要你们了解，Java给我们提供了哪些类，每个类是用在什么场合，当我遇到问题的时候，我知道哪个类，或者哪几个类的组合可以解决我的问题，That'all！，当我们具体写程序的时候，只要你知道该用哪个类来完成你的工作就足够了。编码的时候，具体的方法调用，是边写代码，边查Documentation，所有的东西都在Documentation里面，不要求你一定记住，实际你也记不住3000多个类的总共将近10万个方法调用。所以对每个包的总体框架的把握就变得极为重要。第五步，通过上面的学习，如果学的比较扎实的话，就打好了Java的基础了，剩下要做的工作是扫清Documentation里面除了上面4个包之外的其他一些比较有用处的类。相信进展到这一步，Java的自学能力已经被培养出来了，可以到了直接学习Documentation的水平了。除了要做GUI编程之外，JDK里面其他会有用处的包是这些：java.text.*; .*; javax.naming.*;这些包里面真正用的比较多的类其实很少，只有几个，所以不需要花很多时间。 第六步，Java Web 编程 Web编程的核心是HTTP协议，HTTP协议和Java无关，如果不熟悉HTTP协议的话，虽然也可以学好Servlet/JSP编程，但是达不到举一反三，一通百通的境界。所以HTTP协议的学习是必备的。如果熟悉了HTTP协议的话，又有了Java编程的良好的基础，学习Servlet/JSP简直易如反掌，我学习Servlet/JSP就用了不到一周的时间，然后就开始用JSP来做项目了。 在Servlet/JSP的学习中，重头仍然是Servlet Documentation。Servlet API最常用的类很少，花比较少的时间就可以掌握了。把这些类都看一遍，多写几个例子试试。Servlet/JSP编程本质就是在反复调用这些类来通过HTTP协议在Web Server和Brower之间交谈。另外对JSP，还需要熟悉几个常用JSP的标记，具体的写法记不住的话，临时查就是了。 此外Java Web编程学习的重点要放在Web Application的设计模式上，如何进行业务逻辑的分析，并且进行合理的设计，按照MVC设计模式的要求，运用Servlet和JSP分别完成不同的逻辑层，掌握如何在Servlet和JSP之间进行流程的控制和数据的共享，以及Web Application应该如何配置和部署。第七步，J2EE编程 以上的学习过程如果是比较顺利的话，进行到这一步，难度又陡然提高。因为上面的知识内容都是只涉及一个方面，而像EJB，JMS，JTA等核心的J2EE规范往往是几种Java技术的综合运用的结晶，所以掌握起来难度比较大。 首先一定要学习好JNDI，JNDI是App Server定位服务器资源（EJB组件，Datasouce，JMS）查找方法，如果对JNDI不熟悉的话，EJB，JMS这些东西几乎学不下去。JNDI其实就是javax.naming.*这个包，运用起来很简单。难点在于服务器资源文件的配置。对于服务器资源文件的配置，就需要看看专门的文档规范了，比如web.xml的写法，ejb-jar.xml的写法等等。针对每种不同的App Server，还有自己的服务资源配置文件，也是需要熟悉的。然后可以学习JTA，主要是要理解JTA对于事务的控制的方法，以及该在什么场合使用JTA。这里可以简单的举个例子，我们知道一般情况可以对于一个数据库连接进行事务控制，做为一个原子操作，但是假设我的业务需求是要把对两个不同数据库的操作做为一个原子操作，你能做的到吗？这时候只能用JTA了。假设操作过程是先往A数据库插一条记录，然后删除B数据库另一个记录，我们自己写代码是控制不了把整个操作做为一个原子操作的。用JTA的话，由App Server来完成控制。 在学习EJB之前要学习对象序列化和RMI，RMI是EJB的基础。接着学习JMS和EJB，对于EJB来说，最关键是要理解EJB是如何通过RMI来实现对远端对象的调用的，以及在什么情况下要用到EJB。 在学习完EJB，JMS这些东西之后，你可能会意识到要急不可待学习两个领域的知识，一个是UML，另一个是Design Pattern。Java企业软件的设计非常重视框架(Framework)的设计，一个好的软件框架是软件开发成功的必要条件。在这个时候，应该开始把学习的重点放在设计模式和框架的学习上，通过学习和实际的编程经验来掌握EJB的设计模式和J2EE的核心模式。 J2EE规范里面，除了EJB，JMS，JTA，Servlet/JSP，JDBC之外还有很多很多的企业技术，这里不一一进行介绍了。另外还有一个最新领域Web Services。Web Services也完全没有任何新东西，它像是一种黏合剂，可以把不同的服务统一起来提供一个统一的调用接口，作为使用者来说，我只要获得服务提供者给我的WSDL（对服务的描述），就够了，我完全不知道服务器提供者提供的服务究竟是EJB组件，还是.Net组件，还是什么CORBA组件，还是其他的什么实现，我也不需要知道。Web Services最伟大的地方就在于通过统一的服务提供方式和调用方式，实现了整个Internet服务的共享，是一个非常令人激动的技术领域。Web Services好像目前还没有什么很好的书籍，但是可以通过在网络上面查资料的方式来学习。