@Inherited详解以及各种情况，超级详细！！

结论：

当一个被@Inherited注解修饰的注解作用于类上时，其子类也会被加上该注解。

源码

package java.lang.annotation;

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

该注解是一个源注解，是jdk中定义的。

各种情况

定义注解

HasInherited注解

package com.example.springtest.Inherited;

import java.lang.annotation.*;

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

NoInherited

package com.example.springtest.Inherited;

import java.lang.annotation.*;

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.TYPE)
public @interface NoInherited {
}

类继承关系（父类注解被@Inherited修饰）

package com.example.springtest.Inherited;

@HasInherited
public class FatherClass_HasInherited {
}


package com.example.springtest.Inherited;

public class ChildH extends FatherClass_HasInherited{
}

@SpringBootTest
class SpringTestApplicationTests {
    @Test
    public void fatherClass_HasInherited(){
        Class<ChildH> childHClass = ChildH.class;
        Annotation[] annotations = childHClass.getAnnotations();
        System.out.println("------------------");
        for (Annotation annotation : annotations) {
            System.out.println("注解名："+annotation);
        }
        System.out.println("------------------");
    }

}

结果：子类成功获取父类中被@Inherited修饰的注解

类继承关系（父类注解没有@Inherited修饰）

package com.example.springtest.Inherited;

@NoInherited
public interface FatherInterface_NoInherited {
}

package com.example.springtest.Inherited;

public class ChildN extends FatherClass_NoInherited{
}

@SpringBootTest
class SpringTestApplicationTests {

    @Test
    public void fatherClass_NoInherited(){
        Class<ChildN> childN = ChildN.class;
        Annotation[] annotations = childN.getAnnotations();
        System.out.println("------------------");
        for (Annotation annotation : annotations) {
            System.out.println("注解名："+annotation);
        }
        System.out.println("------------------");
    }
}

结果：子类成功获取不到父类中没有被@Inherited修饰的注解

类实现接口关系（接口注解有@Inherited修饰）

package com.example.springtest.Inherited;
@HasInherited
public interface FatherInterface_HasInherited {
}

package com.example.springtest.Inherited;

public class ChildHI implements FatherInterface_HasInherited{
}

@SpringBootTest
class SpringTestApplicationTests {

    @Test
    public void fatherInterface_HasInherited(){
        Class<ChildHI> childHI = ChildHI.class;
        Annotation[] annotations = childHI.getAnnotations();
        System.out.println("------------------");
        for (Annotation annotation : annotations) {
            System.out.println("注解名："+annotation);
        }
        System.out.println("------------------");
    }
}

结果：子类获取不到父接口中被@Inherited修饰的注解

接口继承接口关系（接口注解有@Inherited修饰）

package com.example.springtest.Inherited;
@HasInherited
public interface FatherInterface_HasInherited {
}

package com.example.springtest.Inherited;

public interface ChildInterface extends FatherInterface_HasInherited{
}

@SpringBootTest
class SpringTestApplicationTests {

    @Test
    public void childInterface(){
        Class<ChildInterface> childInterface = ChildInterface.class;
        Annotation[] annotations = childInterface.getAnnotations();
        System.out.println("------------------");
        for (Annotation annotation : annotations) {
            System.out.println("注解名："+annotation);
        }
        System.out.println("------------------");
    }

}

结果：子接口获取不到父接口中被@Inherited修饰的注解

总结

@Inherited修饰的注解只对实现类的继承有效，对接口的实现是无效的。

参考

@inherited 注解详解
@Inherited详解