J2ee is not only socket programming, but also the core technology in 13.

Core API and components of J2EE

J2EE platform consists of a set of services, application program interfaces (API) and protocols, which provide functional support for the development of multi-tier applications based on Web. The following is a brief description of J2EE 13 technical specification (space is limited, only a brief description can be made here):

1.JDBC(Java database connection):

JDBC API provides a unified way to access different databases. Like ODBC, JDBC hides some details from developers. In addition, JDCB's access to the database is platform-independent.

2.JNDI(Java name and directory interface):

JNDI API is used to perform name and directory services. It provides a consistent model for accessing and manipulating enterprise resources, such as DNS and LDAP, local file systems or objects in application servers.

3.EJB (enterprise JavaBean):

One of the reasons why J2EE technology has won wide media attention is EJB. They provide a framework for developing and implementing distributed business logic, which greatly simplifies the development of scalable and highly complex enterprise-level applications. The EJB specification defines when and how EJB components interact with their containers. Containers are responsible for providing public services, such as directory services, transaction management, security, resource buffer pools and fault tolerance. But it is worth noting that EJB is not the only way to realize J2EE. Because of the openness of J2EE, some vendors can achieve the same goal in a way similar to EJB.

4.RMI (Remote Method Call):

As the name implies, RMI protocol calls methods on remote objects. It uses serialization to transfer data between the client and the server. RMI is a low-level protocol used by EJB.

5.Java IDL/CORBA:

With the support of Java IDL, developers can integrate Java and CORBA. They can create Java objects and make them deployable in CORBA ORB, or they can create Java classes and act as clients of CORBA objects deployed with other ORBs. The latter method provides another way to integrate your new application with the old system using Java.

6.JSP(Java server page):

JSP pages are composed of HTML code and embedded Java code. The server processes these Java codes after the client requests the page, and then returns the generated HTML page to the browser of the client.

7.Java Servlet:

Servlet is a Java applet, which extends the function of Web server. As a server-side application, it starts to execute when requested, which is similar to CGI Perl scripts. Most of the functions provided by Servlet are similar to JSP, but they are implemented in different ways. JSP usually embeds a small amount of Java code in most HTML codes, while servlets are all written in Java to generate HTML.

8.XML (extensible markup language):

XML is a language that can be used to define other markup languages. It is used to enjoy data in different business processes.

The development of XML and Java are independent of each other, but the same goal as Java is platform independence. By combining Java and XML, a perfect platform-independent solution can be obtained.

9.JMS(Java Message Service):

MS is an application program interface (API) for communicating with message-oriented middleware. It supports peer-to-peer domains and publish/subscribe domains, and supports the following types: approved messaging, transactional messaging, consistent messaging and durable subscriber support. JMS also provides another

A way to integrate your application with the old back-end system.

10.JTA(Java transaction architecture):

JTA defines a standard API through which application systems can access various transaction monitoring.

1 1.JTS(Java transaction service):

JTS is the basic implementation of CORBA OTS transaction monitoring. JTS specifies the implementation of the transaction manager. The transaction manager is a Java mirror image, which supports the Java transaction API (JTA) specification at the high level and implements the OMG OTS specification at the low level. JTS transaction manager provides transaction services for application servers, resource managers, independent applications and communication resource managers.

12.JavaMail:

JavaMail is an API for accessing mail servers, which provides a set of abstract classes of mail servers. Support not only SMTP server, but also IMAP server.

13.JAF(JavaBeans activation framework):

JavaMail uses JAF to process mime-encoded MIME attachments. The byte stream of MIME can be converted to and from Java objects. Most applications do not need to use JAF directly.

The first stage (java basic stage)

1.java syntax

2. Object-oriented

3. General API

4. Interface programming

5. Multi-thread operation

6. file io

7.java network planning ..

Look at Zhang Xiaoxiang's java video (but Zhang Xiao

Xiang teacher's mandarin is not very good, and his speech speed is very slow, but the technology is self-evident! Thanks to Mr. Zhang's selfless dedication, hehe)

The second stage (database stage)

1.oracle

2.mysql

3.sql server

At present, the three mainstream databases used by domestic software companies are sql server, mysql and oracle. Oracle database seems to be becoming more and more popular. Generally speaking, PHP corresponds to MySQL database; ASP corresponds to SQL database; JSP corresponds to ORACLE database. So people will watch it often.

In the market, all JAVA training uses ORACLE database. In fact, if you learn ORACLE database first, then MySQL and SQL database, you will find that there are many similarities and it is easy to learn. Oracle Bone Inscriptions, I recommend.

Teacher's Oracle Bone Inscriptions video (Teacher Han's teaching is very interesting, especially suitable for people with poor foundation. There is a set of lectures)

The third stage (web development stage)

1.html

2.css

3.javascript

These three parts are essential technologies for web development. You must study hard, but I didn't find anything particularly good at that time. It seems that many teachers talk about the framework and background, and there are not many interfaces, so there is nothing to recommend. You can.

Looking online, << Unique Light >> This book is very good, but it is not suitable for beginners. You can watch Sun Xin's video "HTML Language Crash".

The fourth stage (middle part of j2ee)

1.servlet

2.jsp

3.mvc

This stage is close to the needs of enterprises, so learning is more difficult. If I don't have a solid study ahead, it will be more troublesome. That's what I do. If I don't fully understand it before, I will learn j2ee intermediate, which will lead to indigestion. Therefore, my younger brother warned everyone in the center to learn the previous ones well first, and then learn the fourth stage. The mvc idea here is not easy to understand, and it is the focus of learning. At the same time, I have to learn tomcat/jboss/wl server, so you may think there is still a lot to learn. In fact, I have wavered here and want to give up for a while. But when I think of the landlord's disdainful expression, I think, I must study hard and mix myself up. My home is in the countryside, so I will farm when I go back. It doesn't matter whether I am a civil servant or not. Moreover, I didn't need the major I studied in my hometown, or I was a network administrator or something. Anyway, I was in a complicated mood. I recommend this stage.

Han Shunping's servlet Video jsp Video (Special thanks to Han Shunping. I prefer his lecture style, because the foundation was not very good at that time, and I was afraid to watch too theoretical classes. )

The fifth stage (advanced part of j2ee)

1.struts

hibernation

3. Spring

After learning Servlet and JSP, I will learn the most advanced and popular software skills of network programming such as Struts, Hibernate and Spring.

The recommended reference books are Servlet and JSP core programming provided by Meihe Books.

The framework is based on Servlet and JSPs. First of all, we should learn Struts framework, a typical MVC pattern. The recommended learning video is Struts video of Zhang Xiaojing. (There are videos of Sun Xin on the Internet, mainly about Struts, Hibernate and Spring, but this seems to have a bad effect of stealing records, which sounds difficult and the connection is not good. )

Sun Qinwei, a recommended book, edited Mastering Struts, Java. Web page design and development based on MVC

Then there is the Hibernate framework, which recommends Hibernate videos from Li Xinghua.

Please refer to Sun's Mastering Java Object Persistence Technology.

Finally, you can find many videos about the Spring framework on the Internet, but the system really didn't find it. In the attitude of being responsible to everyone, I dare not recommend it indiscriminately. Let's search online. Maybe it's possible now.

After learning the above three stages, let's look at XML, Ajax and EJB! Especially ajax is very popular, so our company uses it. Ajax framework is popular (jquery, dw), and our company uses jquery. By the way, you must have the foundation of JavaScript before learning Ajax. It is suggested to develop JavaScript web pages in Zhang Xiaoxiang. This video has the corresponding supporting book JavaScript Web Development.