Java自定义注解

@Target(ElementType.FIELD)  
@Retention(RetentionPolicy.RUNTIME)  
@Documented  
@Repeatable(ShowMessage.ShowMessages.class)  
public @interface ShowMessage {  
    String message() default "hello";  
    @Target(ElementType.FIELD)  
    @Retention(RetentionPolicy.RUNTIME)  
    @Documented  
    @interface ShowMessages {  
        ShowMessage[] value();
    }  
}