如何使用java自定义注解?demo

1、Description.java

  package kzfy.bk.com;   
 
  import java.lang.annotation.Documented;
  import java.lang.annotation.ElementType;
  import java.lang.annotation.Retention;
  import java.lang.annotation.RetentionPolicy;
  import java.lang.annotation.Target;   
 
  @Target(ElementType.TYPE)
  @Retention(RetentionPolicy.RUNTIME)
  @Documented
  public @interface Description {
      String value();
  } 

2、Name.java

  package kzfy.bk.com;   
 
  import java.lang.annotation.Documented;
  import java.lang.annotation.ElementType;
  import java.lang.annotation.Retention;
  import java.lang.annotation.RetentionPolicy;
  import java.lang.annotation.Target;   
 
   //注意这里的@Target与@Description里的不同,参数成员也不同
  @Target(ElementType.METHOD)
  @Retention(RetentionPolicy.RUNTIME)
  @Documented
  public @interface Name {
      String originate();
      String community();
  } 

3、MyTest.java

  package kzfy.bk.com;   
 
  @Description("我的第一个使用自定义注解的类！")
  public class MyTest{
      @Name(originate="空中飞鱼",community="java")
      public String getName(){
          return "java，我的人生路！";
      }   
 
      @Name(originate="博客园",community="写博客")
      public String getName2() {
          return "博客，新的征程！";
      }
  } 

4、运行提取MyTest的类TestAnnotation.java

  package kzfy.bk.com;   
 
  import java.lang.reflect.Method;
  import java.util.HashSet;
  import java.util.Set;   
 
  public class TestAnnotation {
      /**
       * Annotation的API的用法请参见javaDoc文档
       */
       public static void main(String[] args) throws Exception {
           String  CLASS_NAME ="kzfy.bk.com.MyTest";
           Class  test = Class.forName(CLASS_NAME);
           boolean flag = test.isAnnotationPresent(Description.class);
            if(flag){
                Description des = (Description)test.getAnnotation(Description.class);
                System.out.println("描述:"+des.value());
                System.out.println("-----------------");
            }   
 
            //把JavaEyer这一类有利用到@Name的全部方法保存到Set中去
            Method[] method = test.getMethods();
            Set<Method> set = new HashSet<Method>();
            for(int i=0;i<method.length;i++) {
                boolean otherFlag = method[i].isAnnotationPresent(Name.class);
                if(otherFlag) set.add(method[i]);
            }
            for(Method m: set) {
                Name name = m.getAnnotation(Name.class);
                System.out.println("orginate:"+name.originate());
                System.out.println("community:"+name.community());
            }
      }
}