注解继承

接口注解不能被实现类继承。
接口注解不能被子接口继承。
父类接口能被子类接口继承，注解需要被@Inherited元注解注释。

@Inherited
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface TestAnnotation {
}

@Inherited
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface TestComponent {
}

public interface UserService extends UserService1 {
    public void get();
}

@TestAnnotation
public interface UserService1 {
}

public class UserServiceChild extends UserServiceImpl{
}

@TestComponent
public class UserServiceImpl implements UserService {
    @Override
    public void get() {
    }
}

class UserServiceImplTest extends BaseJunit {
    @Test
    void testAnnotation() {
        Annotation[] annotations = UserService.class.getAnnotations();
        for (int i = 0; i < annotations.length; i++) {
            System.out.println("UserService的注解：" + annotations[i]);
        }

        annotations = UserServiceImpl.class.getAnnotations();
        for (int i = 0; i < annotations.length; i++) {
            System.out.println("UserServiceImpl的注解：" + annotations[i]);
        }

        annotations = UserServiceChild.class.getAnnotations();
        for (int i = 0; i < annotations.length; i++) {
            System.out.println("UserServiceChild的注解：" + annotations[i]);
        }

        System.out.println(UserService.class.isAnnotationPresent(TestAnnotation.class));
        System.out.println(UserServiceImpl.class.isAnnotationPresent(TestAnnotation.class));
        System.out.println(UserServiceImpl.class.isAnnotationPresent(TestComponent.class));

        System.out.println(UserServiceChild.class.isAnnotationPresent(TestAnnotation.class));
        System.out.println(UserServiceChild.class.isAnnotationPresent(TestComponent.class));
    }
}

结果：

UserServiceImpl的注解：@com.o3gene.listen_jpa.test.TestComponent()
UserServiceChild的注解：@com.o3gene.listen_jpa.test.TestComponent()
false
false
true
false
true

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