动态代理终极版

2023-11-22 22:35:34

1.首先是一个公共接口

1 public interface Speak{
2   public void sayHello();    
3 }

2.以及一个该接口的子类

1 public class MySpeak implements Speak{
2   public void sayHello(){
3     System.out.println("HelloWorld!");        
4   }  
5 }

3.下面我们可以创建对该接口子类对象具体操作的InvocationHandler子类了

   1:     public class SpeakHandler implements InvocationHandler {
   2:     //需要操作的目标对象
   3:     private Object obj;
   4:     
   5:     public SpeakHandler(Object obj) {
   6:         super();
   7:         this.obj = obj;
   8:     }
   9:  
  10:     /* @see java.lang.reflect.InvocationHandler#invoke
  11:      * (java.lang.Object, java.lang.reflect.Method, java.lang.Object[])
  12:      */
  13:     @Override
  14:     public Object invoke(Object proxy, Method method, Object[] args)
  15:             throws Throwable {
  16:         //执行目标方法前的代码
  17:         before();
  18:         
  19:         //利用反射执行目标对象的对应方法
  20:         Object retVal = method.invoke(obj, args);
  21:         
  22:         //执行目标方法后的代码
  23:         after();
  24:         
  25:         return retVal;
  26:     }
  27:     
  28:     private void before(){
  29:         System.out.println("before");
  30:     }
  31:     
  32:     private void after(){
  33:         System.out.println("after");
  34:     }
  35: }

4.最后测试一下，这样就可以利用Proxy类获取我们的代理类对象了，它没有名字哦

   1: public class ProxyTest {
   2:  
   3:     /**
   4:      * @param args
   5:      */
   6:     public static void main(String[] args) {
   7:         
   8:         //生成目标对象
   9:         MySpeak ms = new MySpeak();
  10:         
  11:         //生成Handler对象
  12:         SpeakHandler speakHandler = new SpeakHandler(ms);
  13:         
  14:         //构造代理类，获取对象
  15:         Speak speak = (Speak)Proxy.newProxyInstance(
  16:                 Speak.class.getClassLoader(),
  17:                 new Class[]{Speak.class},
  18:                 speakHandler);
  19:         
  20:         //执行代理类实现的接口方法
  21:         speak.sayHello();
  22:     }
  23: }

5.最后两部也可以合成一步来写，是这个样子的.

 1 public class ProxyTest {
 2   
 3      /**
 4       * @param args
 5       */
 6     public static void main(String[] args) {
 7          
 8       //生成目标对象
 9       MySpeak ms = new MySpeak();
10          
11       //构造代理类，获取对象
12       Speak speak = (Speak)Proxy.newProxyInstance(
13             Speak.class.getClassLoader(),
14             new Class[]{Speak.class},
15             new InvocationHandler(){
16 
17             //需要操作的目标对象
18             private Object obj;
19      
20             public SpeakHandler(Object obj) {
21                 super();
22                 this.obj = obj;
23             }
24   
25             public Object invoke(Object proxy, Method method, Object[] args)
26             throws Throwable {
27                 //执行目标方法前的代码
28                 before();
29          
30                 //利用反射执行目标对象的对应方法
31                 Object retVal = method.invoke(obj, args);
32          
33                 //执行目标方法后的代码
34                 after();
35          
36                 return retVal;
37             }
38      
39             private void before(){
40                 System.out.println("before");
41             }
42      
43             private void after(){
44                 System.out.println("after");
45             } 
46         });
47             //执行代理类实现的接口方法
48             speak.sayHello();
49      }
50  }

动态代理终极版

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