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This article mainly explains "what is the principle of spring @ Component annotation". Interested friends may wish to have a look at it. The method introduced in this paper is simple, fast and practical. Now let the editor take you to learn "what is the principle of spring @ Component annotations"?

1.@controller controller (injection service)

2.@service service (injecting dao)

3.@repository dao (for dao access)

4.@component (instantiate a normal pojo into a spring container, equivalent to that in a configuration file)

5. Add the classes annotated by the Repository and put them into the spring container for management.

@ Servicepublic class UserServiceImpl implements UserService {} @ Repositorypublic class UserDaoImpl implements UserDao {}

6.

In this way, you can use @ Resource, @ PostConstruct, @ PreDestroy, @ PersistenceContext, @ Autowired, @ Required and other annotations to achieve automatic injection.

7.

Spring provides us with a simplified configuration of context:annotation-config, automatically helps you complete the declaration, and automatically searches @ Component, @ Controller, @ Service, @ Repository and other annotated classes.

In addition to the context:annotation-config function of context:component-scan, context:component-scan can also scan and register javabean under the specified package. It also has the ability to automatically register objects with annotations such as @ component,@service,@Repository in the spring container.

So when you use context:component-scan, you can remove context:annotation-config.

8.spring ioc control inversion

-- Private member variables

@ Autowired@Qualifier ("batchNo") private IdGenerator idGenerator

Equivalent to using @ Component ("")

At this point, I believe you have a deeper understanding of "what is the principle of spring @ Component annotations". You might as well do it in practice. Here is the website, more related content can enter the relevant channels to inquire, follow us, continue to learn!

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