AOP:jdk的动态代理

Posted 2020-08-28 言凡

1.文件结构

2.建立接口

package com.wangcf.manager;


public interface IUserManager {
    
    public void add();
    
    public void del();
    
    public void update();
    
    public String load(int uid);
}

3.实现接口,里面的所有方法都是切入点PointCut

package com.wangcf.manager;


public class UserManagerImp implements IUserManager{
    @Override
    public void add(){
        System.out.println("UserManagerImp add...");
    }
    @Override
    public void del(){
        System.out.println("UserManagerImp del...");
    }
    @Override
    public void update(){
        System.out.println("UserManagerImp update...");
    }

    @Override
    public String load(int uid) {
        // TODO Auto-generatuided method stub
        System.out.println("UserManagerImp load...");
        return "asda"+uid;
    }
}

4.切面拦截，切面类aspect

package com.wangcf.manager;

public class LogManager {
    //advice（通知）
    public static void addLog(){
        System.out.println("添加日志...");
    }
}

5.获取代理类

package com.wangcf.handler;

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

import com.wangcf.manager.LogManager;

public class MyInvocationHandler implements InvocationHandler{

    private Object target;//目标对象
    
    public MyInvocationHandler(Object target) {
        // TODO Auto-generated constructor stub
        this.target=target;
    }
    
    public Object newProxy(){
        Object proxy = Proxy.newProxyInstance(target.getClass().getClassLoader(),
                target.getClass().getInterfaces(), 
                this);
        return proxy;
    }
    
    @Override
    public Object invoke(Object proxy, Method method, Object[] args)
            throws Throwable {
        // TODO Auto-generated method stub
        System.out.println("MyInvocationHandler invoke...");
        /*
         * 
         */
        LogManager.addLog();
        //去执行目标对象的方法
        System.out.println("args: "+args);
        //去执行目标对象的方法
        Object returnValue = method.invoke(target, args);
        System.out.println("returnValue:"+returnValue);
        return returnValue;
    }

}

6.测试类

package com.wangcf.test;

import com.wangcf.handler.MyInvocationHandler;
import com.wangcf.manager.IUserManager;
import com.wangcf.manager.UserManagerImp;

public class TestAction {
    public static void main(String[] args) {
　　　　　//目标对象userManager
        IUserManager userManager=new UserManagerImp();
        
        //下面这段获取代理
        MyInvocationHandler mh=new MyInvocationHandler(userManager); 
        Object proxy=mh.newProxy();
        System.out.println(proxy.getClass().getName());
        IUserManager userManagerProxy=(IUserManager)proxy; 
        
        //不带参数add,和load方法称为连接点JoinPoint
        userManagerProxy.add();
        System.out.println("==============");
        //带参数
        userManagerProxy.load(10);
    }
}

7.输出：

8.总结：

Proxy0是动态获取的代理

通过连接点进入切面，LogManager为切面类