cglib 代理实现

cglib代理的原理是通过继承实现对目标对象的代理

//1.接口
package cn.itcast.service;

public interface UserService {
	void save();
	void delete();
	void update();
	void find();
}

// 接口的实现类 -->被代理的对象
package cn.itcast.service;

public class UserServiceImpl implements UserService {
	@Override
	public void save() {
		System.out.println("保存用户!");
		//int i = 1/0;
	}
	@Override
	public void delete() {
		System.out.println("删除用户!");
	}
	@Override
	public void update() {
		System.out.println("更新用户!");
	}
	@Override
	public void find() {
		System.out.println("查找用户!");
	}
}

//3.实现cglib代理
package cn.itcast.c_proxy;

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

import org.springframework.cglib.proxy.Callback;
import org.springframework.cglib.proxy.Enhancer;
import org.springframework.cglib.proxy.MethodInterceptor;
import org.springframework.cglib.proxy.MethodProxy;

import cn.itcast.service.UserService;
import cn.itcast.service.UserServiceImpl;

//观光代码=>cglib代理
public class UserServiceProxyFactory2 implements MethodInterceptor {

	public UserService getUserServiceProxy(){

		Enhancer en = new Enhancer();//帮我们生成代理对象

		en.setSuperclass(UserServiceImpl.class);//设置对谁进行代理

		en.setCallback(this);//代理要做什么

		UserService us = (UserService) en.create();//创建代理对象

		return us;
	}

	@Override
	public Object intercept(Object prxoyobj, Method method, Object[] arg, MethodProxy methodProxy) throws Throwable {
		//打开事务
		System.out.println("打开事务!");
		//调用原有方法
		Object returnValue = methodProxy.invokeSuper(prxoyobj, arg);
		//提交事务
		System.out.println("提交事务!");

		return returnValue;
	}

}

//4.测试文件
package cn.itcast.c_proxy;

import org.junit.Test;

import cn.itcast.service.UserService;
import cn.itcast.service.UserServiceImpl;

public class Demo {

	@Test
	//动态代理
	public void fun1(){
		UserService us = new UserServiceImpl();

		UserServiceProxyFactory factory = new UserServiceProxyFactory(us);

		UserService usProxy = factory.getUserServiceProxy();

		usProxy.save();

		//代理对象与被代理对象实现了相同的接口
		//代理对象 与 被代理对象没有继承关系
		System.out.println(usProxy instanceof UserServiceImpl );//false
	}

	@Test
	public void fun2(){

		UserServiceProxyFactory2 factory = new UserServiceProxyFactory2();

		UserService usProxy = factory.getUserServiceProxy();

		usProxy.save();

		//判断代理对象是否属于被代理对象类型
		//代理对象继承了被代理对象=>true
		System.out.println(usProxy instanceof UserServiceImpl );//true
	}
}