InvocationHandler接口

public interface InvocationHandler{  
    public Object invoke(Object proxy,Method method,Object[] args)throws Throwable  
}

参数说明:

Object proxy:被代理的对象

Method method:要调用的方法

Object args[]:方法调用时所需要的参数

Proxy类

Proxy类是专门完成代理的操作类,可以通过此类为一个或多个接口动态地生成实现类,此类提供了如下的操作方法:

public static Object newProxyInstance(ClassLoader loader,  
            Class<?>[] interfaces,  
            InvocationHandler h)  
            throws IllegalArgumentException 

参数说明:

ClassLoader loader:类加载器

Class<?>[] interfaces:得到全部的接口

InvocationHandler h:得到InvocationHandler接口的子类实例

动态代理:

package com.itmyhome;  

import java.lang.reflect.InvocationHandler;  
import java.lang.reflect.Method;  
import java.lang.reflect.Proxy;  

interface IHello{    //定义接口  
    public void sayHello();  
}  
class HelloImpl implements IHello{  

    @Override  
    public void sayHello() {  
        // TODO Auto-generated method stub  
        System.out.println("hello itmyhome");  
    }  
}  
class MyInvocationHandler implements InvocationHandler{  

    private Object obj;   //真实主题类  
    public Object bind(Object obj){  
        this.obj = obj;  
        return Proxy.newProxyInstance(obj.getClass().getClassLoader(),
               obj.getClass().getInterfaces(), this);  
    }  
    @Override  
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {  
        System.out.println("***before***");  
        Object temp = method.invoke(obj, args);  
        System.out.println("***after***");  
        return temp;  
    }  
}  

public class T {  
    public static void main(String[] args) throws Exception{  
        IHello h = (IHello)new MyInvocationHandler().bind(new HelloImpl());  
        h.sayHello();  
    }  
}