How to combine multiple annotations to single one?

问题

I have two annotations from a framework. Often I use those two annotations both on the same field. Thus I'm trying to create a "combined" annotation that contains that both two.

But I don't know if it is possible at all:

The existing annotations (that I have no control of):

@Target({ElementType.PARAMETER, ElementType.METHOD, ElementType.FIELD})
@Retention(RetentionPolicy.RUNTIME)
public @interface ApiParam {
    String name() default "";
}

@Target({ElementType.METHOD, ElementType.FIELD})
@Retention(RetentionPolicy.RUNTIME)
public @interface ApiModelProperty {
    String name() default "";
}

My Custom annotation that I'm trying to create:

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.ANNOTATION_TYPE)
@ApiParam
@ApiModelProperty
public @interface SwaggerParam {
     String name() default "";
}

Result: the annotations are not applicable to annotation type.

Question: Is there any chance?

回答1:

Unfortunately you can't do this since it is not possible to extend annotations.

Is there something like Annotation Inheritance in java?

When I first answered this I was initially confused by the Spring framework approach to this shortcoming whereby they use meta level annotations (such as @Component as a meta annotation for @Controller/@Configuration etc.) as a sort of workaround.

See: https://docs.spring.io/spring/docs/3.2.x/spring-framework-reference/html/beans.html#beans-annotation-config

来源：https://stackoverflow.com/questions/47175378/how-to-combine-multiple-annotations-to-single-one

标签

java

Spring

annotations