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How to analyze JavaEE? in view of this problem, this article introduces the corresponding analysis and answer in detail, hoping to help more partners who want to solve this problem to find a more simple and feasible way.

JavaEE is a new name for J2EE, and the purpose of changing its name is to make it clear that J2EE is just a Java enterprise application. In the speech of China Software Technology Conference on Ioc microcontainer (that is, the implementation principle of Jdon framework) at the end of 2004, it was pointed out that we need a microcontainer across J2SE/WEB/EJB to protect our business core components (middleware) to continue its vitality instead of relying on the J2SE/J2EE version. Brief introduction

JavaEE is a new name for J2EE. The purpose of changing its name is to make it clear that J2EE is only a Java enterprise application. With the birth of the concept of WEB and EJB container, the software application industry begins to worry about whether the partners of SUN continue to launch a refurbished standard framework on the Java platform, which makes the business core component architecture of the software application industry at a loss. This hesitation has been explained in the discussion about whether EJB is needed all the time.

In the speech of China Software Technology Conference on Ioc microcontainer (that is, the implementation principle of Jdon framework) at the end of 2004, it was pointed out that we need a microcontainer across J2SE/WEB/EJB to protect our business core components (middleware) to continue its vitality instead of relying on the J2SE/J2EE version. The renaming of J2EE to Java EE actually reflects the common aspiration of the industry.

The core of JavaEE is EJB3.0, which provides a more convenient and convenient enterprise application framework.

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It is worth pointing out that this Java persistence standard can also be embedded in the WEB layer call, so it certainly will not be subordinate to the EJB standard, so that all the current Java persistence layer standards such as: JDBC/JDO/Hibernate/Entity Bean will be unified, reducing the pain of users' architecture choices.

The difference between EJB 3.0 and EJB 2.0

As you can see from the architecture diagram, no matter the Web structure or the EJB structure, the functions provided are similar, so that our business core components can be deployed and run in Web or EJB as needed, without relying on the specific Java EE container. The goal of the figure in the previous chapter can be achieved in Java EE 5.

Of course, an important change in Java EE 5 is that Java EE no longer focuses on the development of large-scale commercial systems as before, but pays more attention to the development of small to medium-sized systems, simplifying this part of the system development steps.

The biggest feature of implementing this simplified action is to add Annotations in Java 5.0. through the introduction of Annotations, to reduce the pain of writing both code and XML configuration files when Java EE development, back and forth to take care of, tired, Annotations not only benefited from the C++ language, but also gained experience from the open source project xDoclet practice.

But Annotations is a double-edged sword. If beginners do not use it well, it will make the Hard code (hard coding) originally in XML be written into the code Annotations, thus destroying the simplicity and flexibility of the code.

Of course, the introduction of Annotations is not only to solve the problem of XML configuration, but also to solve the problem of resource injection (XML belongs to one of the resources). In principle J2EE, container-managed resources are provided to applications by JNDI, and injection can be easily realized through Annotations.

The design concept of resource injection (Resource injection) actually comes from the Ioc pattern (Dependency Injection). The Jdon framework designed and developed by the author has already achieved the purpose of Annotations. In the Jdon framework application demonstration source code SimpleJdonFrameworkTest, there is a configuration in jdonframework.xml as follows:

This configuration injects the database's JNDI name java:/TestDS into the JdbcDAO. The next version of Jdon Framework will be based on Java 5.0.This line of configuration will be writable in jdbcDAO code through Annotations for programmers to develop.

From here, you can also know the difference between EJB 3.0 and EJB 2.0. some people wonder whether they are learning EJB 3.0 or learning EJB 2.0. in fact, EJB 3.0 does not have much change in the principle and mechanism of EJB, but only makes a simplification in programming. In addition, EJB CMP refers to the new features of Hibernate. The biggest simplified change in EJB 3.0 is the CMP programming method. So, no matter how to learn the principles and operating mechanism of EJb 3.0 EJB 2.0, this part is the most difficult part of learning EJB, not because it is easy to understand EJB when it comes to EJB 3.0.

The answer to the question about how to analyze JavaEE is shared here. I hope the above content can be of some help to you. If you still have a lot of doubts to be solved, you can follow the industry information channel to learn more about it.

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