JDK动态代理

1、需要代理的类

package com.sgl.invocation;

public class Vendor implements Sell{

    @Override
    public void sell() {
        System.out.println("In sell method"); 
    }

    @Override
    public void add() {
        System.out.println("add method");
    }

}

2、InvocationHandler

package com.sgl.invocation;

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

public class DynamicProxy implements InvocationHandler{
    
    private Object object;//目标对象
    
    
    public DynamicProxy(Object object) {
        super();
        this.object = object;
    }


    @Override
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {//proxy为代理类对象
        System.out.println("before");
        Object result = method.invoke(object, args);
        System.out.println("after");
        return result;
    }
    
    /**
     * 根据目标对象生成代理对象
     * @return
     */
    public Object getProxy(){
        return Proxy.newProxyInstance(Thread.currentThread().getContextClassLoader(), object.getClass().getInterfaces(), this);
    }

}

3、测试类

package com.sgl.invocation;

public class ProxyTest {
    public static void main(String[] args) {
        //实例化目标对象
        Sell sell = new Vendor();
        // 实例化InvocationHandler
        DynamicProxy invocationHandler = new DynamicProxy(sell);
        // 根据目标对象生成代理对象
        Sell proxy = (Sell) invocationHandler.getProxy();
        // 调用代理对象的方法
        proxy.add();
    }
}

总结：现在只会用，底层原理暂时看不懂！