java动态代理入门示例

package com.huzy.proxy;

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

public class ProxyDemo {
	public static void main(String[] args) {
		//测试
		UserDAO userDAO = new UserDAOImpl();
		MyInvocationHandler invocationHandler = new MyInvocationHandler();
		invocationHandler.setTarget(userDAO);
		UserDAO proxyUserDAO = (UserDAO) Proxy.newProxyInstance(userDAO.getClass().getClassLoader(), new Class[]{UserDAO.class}, invocationHandler);
		proxyUserDAO.save();
	}
}

class MyInvocationHandler implements InvocationHandler {

	private Object target;
	
	public void before() {
		System.out.println("before method invoke do something");
	}
	@Override
	public Object invoke(Object proxy, Method method, Object[] args)
			throws Throwable {
		this.before();
		method.invoke(target, args);
		return null;
	}
	
	public Object getTarget() {
		return target;
	}
	
	public void setTarget(Object target) {
		this.target = target;
	}
}

interface UserDAO {
	public void save();
}

class UserDAOImpl implements UserDAO{

	@Override
	public void save() {
		System.out.println("user dao save invoke");
	}
	
}