动态代理4-手写aop

项目结构

/MySpringAop/src/service/CartService.java

package service;

public interface CartService {
    public String findCartById(Long id);
    public void deleteCart();
}

/MySpringAop/src/service/CartServiceImpl.java

package service;

public class CartServiceImpl implements CartService{

    @Override
    public String findCartById(Long id) {
        System.out.println("CartServiceImpl.findCartById()");
        return "cart";
    }

    @Override
    public void deleteCart() {
        System.out.println("CartServiceImpl.deleteCart()");
    }

}

package aspect;
//自动调用
public class TimeAspect {
    long startTime;
    //得到起始时间
    //@before
    public void getStartTime()
    {
        startTime=System.currentTimeMillis();
    }
    //得到接收时间
    public void getEndTime()
    {
        long endTime=System.currentTimeMillis();
        System.out.println("运行时间:"+(endTime-startTime));
    }
}

package test;

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

import aspect.TimeAspect;
import service.CartService;
import service.CartServiceImpl;

public class MySpringAOP {

    public static void main(String[] args) {
        //1.得到动态代理对象
        CartServiceImpl targetObject=new CartServiceImpl();
        Object proxyObject=getProxyObject(targetObject);
        //2.通过动态代理对象调用目标方法
        CartService cartService=(CartService) proxyObject;
        String result=cartService.findCartById(30L);
        System.out.println(result);
        System.out.println("===========");
        cartService.deleteCart();
        //3.java虚拟机会调用MyInvocationHandler中的invoke()
    }
    //得到动态代理对象
    static Object getProxyObject(Object target)
    {
        //动态类
        ClassLoader classLoader=target.getClass().getClassLoader();
        Class<?>[] methodInfo=target.getClass().getInterfaces();
        MyInvocationHandler handler=new MyInvocationHandler(target);
        return Proxy.newProxyInstance(classLoader, methodInfo, handler);
    }
    //自动调用@before方法
    static class MyInvocationHandler implements InvocationHandler{

        //目标对象是cartServiceImpl对象
        Object target;
        
        public MyInvocationHandler(Object target) {
            this.target = target;
        }


        @Override
        public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
            //调用@before方法
            TimeAspect timeAspect=new TimeAspect();
            timeAspect.getStartTime();
            System.out.println("===开始执行===");
            //调用目标方法
            Object result = method.invoke(target, args);
            System.out.println("===结束执行===");
            timeAspect.getEndTime();
            return result;
        }
        
    }
}

运行结果

===开始执行===
CartServiceImpl.findCartById()
===结束执行===
运行时间:1
cart
===========
===开始执行===
CartServiceImpl.deleteCart()
===结束执行===
运行时间:0