1 interface Subject{void doSth();}
 2 class RealSubject implements Subject{
 3     public void doSth(){
 4         System.out.println("RealSubject doSth....");
 5     }
 6 }
 7 class ProxyHandler implements InvocationHandler
 8 {
 9     private Object obj;
10     public ProxyHandler(Object obj){ this.obj = obj; }
11     //private Subject subject;
12     //public ProxyHandler(Subject subject){this.subject = subject;}
13     public Object invoke(Object proxy, Method method, Object[] args) throws InvocationTargetException, IllegalAccessException
14     {
15         System.out.println(proxy.getClass().getName());
16         System.out.println("before -----------");
17         Object result = method.invoke(this.obj, args);
18         System.out.println("after -----------");
19         return result;
20     }
21 }
22 public class Test{
23     public static void main(String[] args){
24         Subject proxy = (Subject)Proxy.newProxyInstance(
25                 Subject.class.getClassLoader(),
26                 new Class[]{ Subject.class },
27                 new ProxyHandler(new RealSubject()));
28         proxy.doSth();
29         System.out.println(proxy.getClass().getName());
30     }
31 }
32 /*out：
33 com.wrb.$Proxy0
34 before -----------
35 RealSubject doSth....
36 after -----------
37 com.wrb.$Proxy0
38 */

 1 interface UserService {
 2     void add();
 3 }
 4 class UserServiceImpl implements UserService {
 5     public void add() {
 6         System.out.println("add");
 7     }
 8 }
 9 /**
10  * 实现自己的InvocationHandler
11  */
12 class MyInvocationHandler implements InvocationHandler {
13 
14     // 目标对象
15     private Object target;
16 
17     /**
18      * 构造方法
19      * @param target 目标对象
20      */
21     public MyInvocationHandler(Object target) {
22         super();
23         this.target = target;
24     }
25 
26     /**
27      * 执行目标对象的方法
28      */
29     public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
30         System.out.println("before------------------");
31 
32         Object result = method.invoke(target, args);
33 
34         System.out.println("after------------------");
35         return result;
36     }
37 
38     /**
39      * 获取目标对象的代理对象
40      * @return代理对象
41      */
42     public Object getProxy() {
43         return Proxy.newProxyInstance(
44                 Thread.currentThread().getContextClassLoader(),
45                 target.getClass().getInterfaces(),
46                 this);
47     }
48 }
49 public class Test{
50     public static void main(String[] args){
51         MyInvocationHandler handler = 
52                             new MyInvocationHandler(new UserServiceImpl());
53         UserService proxy = (UserService) handler.getProxy();
54         proxy.add();
55     }
56 }
57 /*out：
58 before------------------
59 add
60 after------------------
61 */