Java entry: J2EE learning process. Let's take a look at it for beginners and veterans!

Java entry: J2EE learning process. Let's take a look at it for beginners and veterans!

Java has developed into three main parts by application: j2se, j2-and J2EE. These three modules complement each other and have different application scopes.
J2se is the standard version of Java2 and is mainly used for programming desktop applications;
Mainly used for embedded system development, such as mobile phone and PDA programming;
J2EE is the Enterprise Edition of Java2 and is mainly used for distributed networks.ProgramSuch as e-commerce websites and ERP systems.

Learn j2se first
To learn J2EE, you must first learn j2se. At the beginning, you are advised not to use IDE, and then gradually transition to using IDE for development. After all, it is convenient to use it. Two books are recommended for learning j2se, Java2 Core Technology 1-2, Java programming ideas, and java mode. Among them, "Java programming ideas" should be studied and intensively read. This period of time is basic learning, and it may take a long time or a short time, depending on the level of the learner.

Do not be entangled by IDE

In the course of learning Java and J2EE, you will encounter a wide variety of Ides. Don't be confused by them. When learning Java, you should learn the language, and don't care too much about the additional functions of IDE, it is easy to convert Java programming between different ides. If you care too much about ide functions, it is easy to delay your understanding of the language. Currently, popular ides include JBuilder, enhanced version wsad of eclipse and eclipse. Use one of them. We recommend that you start with eclipse J2EE. JBuilder is more suitable for writing j2se programs.

Select and learn server usage Configuration

When you have j2se and IDE experience, you can start learning J2EE. The web server is tomcat, which is undoubtedly the first choice for Learning Web Services. Currently, there are three application servers: JBoss, WebLogic, and websphere. Many projects start to adopt JBoss, and a large number of companies start to transplant WebSphere or WebLogic to the JBoss Application Server (saving costs, I think it is the first choice and the easiest way to get started with Tomcat and JBoss. It is best to ask experienced people (if conditions are met) to learn the server configuration, because they can solve the problem in one sentence, it may take one or two days for you to explore the Internet on your own (I did this silly thing). We should focus on learning principles and theories, the use of a particular technology will never replace one's knowledge and knowledge.

Learn Web Knowledge

If you are using an e-commerce website, you may have to play several roles:
HTML, may need to use dreamwave and other ide.
Javascript, learn simple data verification, Data Association display, and so on.

J2eeapi Learning

Learning j2eeapi and learning server should be an iterative process.

First, I learned a lot about JSP and Servlet programming. I have established two "JSP design" and "Java Servlet programming" books by oreilly. the books written by oreilly are always outstanding and have to be admired.

To learn JDBC database programming, most J2EE projects are MIS systems, and database access is the core. This should belong to j2se learning. Here we will emphasize it.

Learn the jndi api, which can be combined with learning EJB.

Learning ejb api, recommended book "Excellent EJB"

After the above learning, we can probably deal with general applications.

Some people say that they can follow Sun's J2EE tutorial.

Strong> learn the EJB Design Mode and viewCode(Most important)

The design pattern is an internal skill, so the importance of it can be said. If you don't use the design pattern, you will write a bunch of spam using ejbs, which is slow and a bunch of bugs, the result is not as good as EJB implementation (EJB is not equal to J2EE)

 

No matter what language you want to learn, you should read a lot of code. If you don't have a certain amount of code, you cannot learn J2EE.

Currently, many open-source projects can be used as teaching materials:

Jive Forum
PetStore sun
Dune sun

Wait, read one and use it in your own project.

Other J2EE Learning

When you get to know a certain degree of depth about J2EE, you need to pay attention to some technical changes in the current field. J2EE is a field of competition and everyone puts forward their own solutions here, for example, structs, hiberate, OFBiz, etc. Learning these things depends on your project and goals. It is not necessary to add them in advance, but it does not need to be too deep, after all, learning principles and theories are the most important thing.

J2eeapi
Assumerver pages (JSP) technology 1.2
Java Servlet technology 2.3
Jdbc api 2.0
Java XML processing API (JAXP) 1.1
2.0 Enterprise JavaBeans Technology
Java Messaging Service (JMS) 1.0
Java Naming Directory Interface (JNDI) 1.2
Java transaction API (JTA) 1.0
Java sdk api 1.2
Javajans activation architecture (JAF) 1.0
J2EE Connector Architecture (JCA) 1.0
Java authentication and authorization Service (JAAS) 1.0

Learning some of the above APIs depends on your project. It is good to know all of them.

As mentioned above, the Java language itself is not difficult to learn, but there are too many technologies, so it is very difficult to learn Java. In retrospect, almost every beginner may ask such a sentence when learning java. How do you know which method (API) is in which package? Haha, no other, but skilled.