java里面的Annotation的使用

eclipse里面建工程, 三个source文件

package com.sap;import java.lang.annotation.*;@Target(ElementType.PACKAGE)@Retention(RetentionPolicy.RUNTIME)public @interface PkgAnnotation {String value();String desc();}

@PkgAnnotation(value="anno value", desc="i am description for annotation")package com.sap;

package com.sap;import java.lang.annotation.*;public class Client {/** * @param args */public static void main(String[] args) {// TODO Auto-generated method stubPackage pkg = Package.getPackage("com.sap");boolean flag = pkg.isAnnotationPresent(PkgAnnotation.class);if (flag){Annotation[] annos =pkg.getAnnotations();for(Annotation an : annos){if (an instanceof PkgAnnotation){System.out.println(((PkgAnnotation) an).value());System.out.println(((PkgAnnotation) an).desc());}}}}}

输出:

anno value
i am description for annotation