SpringSource Javax Annotation in -depth interpret

SpringSource Javax Annotation in -depth interpret In Java programming, annotation is a metadata, which provides us with a convenient way to embed metadata information in the program.The Spring framework also provides a series of annotations to simplify development, including SpringSource Javax Annotion.In this article, we will thoroughly interpret the role and usage of the meta -annotation of SpringSource Javax Annotion. First of all, let's find out what the meta -annotation is.Metropolitan annotations are a note that can be used to annotate other annotations, which can be used to create custom annotations.SpringSource Javax Annotion provides several commonly used meta -solutions, including@Retention,@Target,@Inherited, and @Documented, etc. The @Reking meta -notes are used to specify the annotation of its annotations. The retention strategy of the annotation includes three strategies, namely the RetentionPolicy.source, RetentionPolicy.classs, and RetentionPolicy.runtime.@Target Macauxing is used to specify the annotation of the annotation of it, and can be used to mark places, such as categories, methods, variables, etc.@Inherited's Note is used to specify whether it can be inherited by the annotation of it.@Documented meta -injection is used to specify the annotation of its annotation and should be recorded by the Javadoc tools. In addition to the meta -injection, SpringSource Javax Annotion also provides some commonly used annotations, such as@AutoWired,@Component,@Service and @RePOSITORY.These annotations allow us to implement functions such as dependency injection, declaration components, and access database in Spring applications. Let's take a look at a simple example of use. Suppose we have a UserService interface and UserServiceImpl implementation class: public interface UserService { void saveUser(User user); } @Component public class UserServiceImpl implements UserService { @Autowired private UserRepository userRepository; @Override public void saveUser(User user) { userRepository.save(user); } } In this example, we used @Component annotations to declare the userServiceImpl as a component, so that the Spring container can automatically scan and instantiated it.The @Autowired annotation indicates that we hope that the Spring container will automatically inject an instance of UserRePOSITORY into UserServiceImpl. By using the annotations provided by SpringSource Javax Annotion, we can achieve more concise and efficient development in the Spring application.In -depth understanding of the role and use of meta annotations can help us better use these annotations and better understand the annotation mechanism in the Spring framework.I hope this article can help readers better master the use of Springsource Javax Annotation.