注解开发

 1 @Documented//拥有这个注解的元素可以被javadoc文档化
 2 @Target(ElementType.METHOD)
 3 //该注解可以注解的程序元素返回,不添加则表示可以注解任何程序元素
 4 @Inherited//该注解类型被自动继承
 5 @Retention(RetentionPolicy.RUNTIME)
 6 //指明该注解被保留的时间长短
 7 public @interface InfoMethod {
 8      String author() default "sookie" ;
 9      String date();
10      int version() default 1;
11      String comments();
12 }

public class Test {
     @Override
     @InfoMethod(author= "22",comments="Main method",date="2016-02-04")
     //存在默认值的注解方法,使用时可以不传值,其余都要传值
     public String toString(){
           return "Overriden toString method" ;
     }
     
     @Deprecated
     @InfoMethod(author= "33",comments="Deprecated method",date="2016-02-16")
     public static void oldMethod (){
          System. out.println("该方法已过时" );
     }
     
     @SuppressWarnings({ "unchecked", "rawtypes" })
     @InfoMethod(comments= "SuppressWarnings method",date="2016-02-16")
     public static void genericsTest(){
          List list = new ArrayList();
          list.add( "OK");
           oldMethod();
     }
}

public static void main(String[] args) throws Exception{
     
     Class<Test> cls = (Class<Test>) Test. class;
     for(Method method : cls.getDeclaredMethods()){
           //获取到该类中的所有方法(不包括继承的)并执行遍历
           if(method.isAnnotationPresent(InfoMethod.class)){
               //如果指定类型的注解存在于此元素上
               for(Annotation anno : method.getAnnotations()){
                   System.out.println(method.getName()+"方法上的注解有" +anno);
              }
               InfoMethod methodAnno = method.getAnnotation(InfoMethod.class);
               //获取到该方法上的InfoMethod注解对象
               System.out.println("--author:" +methodAnno.author());
               System.out.println("--date:" +methodAnno.date());
               System.out.println("--comments:" +methodAnno.comments());
              
          }
     }
}