InvocationHandler_demo

 1 package com.hmb;
 2 
 3 public class HelloImpl implements IHello {
 4     @Override
 5     public void sayHello() {
 6         System.out.println("hello impl");
 7     }
 8 
 9     @Override
10     public void sayGoodBye() {
11         System.out.println("goodbye impl");
12     }
13 }

 1 package com.hmb;
 2 
 3 import java.lang.reflect.InvocationHandler;
 4 import java.lang.reflect.Method;
 5 
 6 public class HelloHandler implements InvocationHandler {
 7 
 8     private final IHello iHello;
 9 
10     public HelloHandler(IHello iHello) {
11         this.iHello = iHello;
12     }
13 
14     @Override
15     public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
16         String methodName = method.getName();
17 
18         switch (methodName) {
19             case "sayHello":
20                 System.out.println("log before sayHello");
21                 method.invoke(iHello, args);
22                 break;
23             case "sayGoodBye":
24                 System.out.println("log before sayGoodBye");
25                 method.invoke(iHello, args);
26                 break;
27             default:
28                 System.out.println("log before other method");
29                 method.invoke(iHello, args);
30         }
31 
32         return null;
33     }
34 }

 1 package com.hmb;
 2 
 3 import java.lang.reflect.Proxy;
 4 
 5 public class Main {
 6     public static void main(String[] args) {
 7         IHello hello = new HelloImpl();
 8         IHello iHello = (IHello) Proxy.newProxyInstance(hello.getClass().getClassLoader(),
 9                 hello.getClass().getInterfaces(),
10                 new HelloHandler(hello));
11         iHello.sayHello();
12         iHello.sayGoodBye();
13     }
14 }