能够在核心业务方法前后做一些你所想做的辅助工作，如log日志，安全机制等等。
import java.lang.reflect.*;
public interface Business{public void do();}
public class BusinessImp implements Business{public void do(){。。。}}
public class MyInvocationHandler implements InvocationHandler{
private Object target = null;
public MyInvocationHandler(Object target){this.target = target;}
@Override
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable{
调用核心业务方法前操作
Object result = method.invoke(target, args);
调用核心业务方法后操作
return result;//返回代理对象
}
}
public class Test{
BusinessImp busi = new BusinessImp();//被代理对象
MyInvocationHandler handler = new MyInvocationHandler(busi);
Business proxy = (Business)Proxy.newProxyInstance(busi.getClass().getClassLoader(), busi.getClass().getInterface(),handler);
proxy.do();//调用do时会调用handler的invoke方法
}