如何强制 Java 子类定义注释? [英] How do I force a Java subclass to define an Annotation?

问题描述

如果一个类定义了一个注解，是否可以强制其子类定义相同的注解?

If a class defined an annotation, is it somehow possible to force its subclass to define the same annotation?

例如，我们有一个简单的类/子类对，它们共享 @Author @interface.我想要做的是强制每个进一步的子类定义相同的 @Author 注释，防止 RuntimeException 在路上的某个地方.

For instance, we have a simple class/subclass pair that share the @Author @interface. What I'd like to do is force each further subclass to define the same @Author annotation, preventing a RuntimeException somewhere down the road.

TestClass.java:

TestClass.java:

import java.lang.annotation.*;

@Retention(RetentionPolicy.RUNTIME)
@interface Author { String name(); }

@Author( name = "foo" )
public abstract class TestClass
{
    public static String getInfo( Class<? extends TestClass> c )
    {
        return c.getAnnotation( Author.class ).name();
    }

    public static void main( String[] args )
    {
        System.out.println( "The test class was written by "
                        + getInfo( TestClass.class ) );
        System.out.println( "The test subclass was written by " 
                        + getInfo( TestSubClass.class ) );
    }
}

TestSubClass.java:

TestSubClass.java:

@Author( name = "bar" )
public abstract class TestSubClass extends TestClass {}

我知道我可以在运行时枚举所有注释并检查缺少的 @Author，但如果可能的话，我真的很想在编译时这样做.

I know I can enumerate all annotations at runtime and check for the missing @Author, but I'd really like to do this at compile time, if possible.

推荐答案

您可以在编译时使用 JSR 269 做到这一点.请参阅:http://today.java.net/pub/a/today/2006/06/29/validate-java-ee-annotations-with-annotation-processors.html#pluggable-annotation-processing-api

You can do that with JSR 269, at compile time. See : http://today.java.net/pub/a/today/2006/06/29/validate-java-ee-annotations-with-annotation-processors.html#pluggable-annotation-processing-api

编辑 2020-09-20:链接已失效，存档版本在这里:https://web.archive.org/web/20150516080739/http://today.java.net/pub/a/today/2006/06/29/validate-java-ee-annotations-with-annotation-processors.html

Edit 2020-09-20: Link is dead, archived version here : https://web.archive.org/web/20150516080739/http://today.java.net/pub/a/today/2006/06/29/validate-java-ee-annotations-with-annotation-processors.html

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