org.springframework.beans.factory.annotation

## 注释类型 Required

-     @Retention(value=RUNTIME)
       @Target(value=METHOD)
      public @interface Required

  Marks a method (typically a JavaBean setter method) as being 'required': that is, the setter method must be configured to be dependency-injected with a value.

  Please do consult the javadoc for the `RequiredAnnotationBeanPostProcessor` class (which, by default, checks for the presence of this annotation).

  从以下版本开始:
    2.0
  作者:
    Rob Harrop
  另请参阅:
    `RequiredAnnotationBeanPostProcessor`