动态代理

动态代理代码回顾

 

package cn.itcast.c_proxy;

 

import java.lang.reflect.InvocationHandler;

import java.lang.reflect.Method;

import java.lang.reflect.Proxy;

 

import cn.itcast.service.UserService;

import cn.itcast.service.UserServiceImpl;

//观光代码=>动态代理

public class UserServiceProxyFactory implements InvocationHandler {

public UserServiceProxyFactory(UserService us) {

super();

this.us = us;

}

 

private UserService us;

public UserService getUserServiceProxy(){

//生成动态代理

UserService usProxy = (UserService) Proxy.newProxyInstance(UserServiceProxyFactory.class.getClassLoader(),

UserServiceImpl.class.getInterfaces(),

this);

//返回

return usProxy;

}

 

@Override

public Object invoke(Object arg0, Method method, Object[] arg2) throws Throwable {

System.out.println("打开事务!");

Object invoke = method.invoke(us, arg2);

System.out.println("提交事务!");

return invoke;

}

 

}

 

 

@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

}

 

package cn.itcast.service;

 

public interface UserService {

void save();

void delete();

void update();

void find();

}

 

 

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!");

}

}

 

 

打开事务!

保存用户!

提交事务!

false

 

07-手动使用cglib代理(了解)_

 

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;

}

 

 

}

 

 

测试：

 

@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

}