静态代理和动态代理的代码笔记

基础类，创建一个接口和一个实现方法

package com.opk.proxy;

public interface BuyHouse {
    void buyHouse();
}

package com.opk.proxy;

public class BuyHouseImpl implements BuyHouse {
    @Override
    public void buyHouse() {
        System.out.println("我要买房");
    }
}

静态代理的实现

package com.opk.proxy;

public class BuyHouseProxy implements BuyHouse {
    private BuyHouse buyHouse;

    public BuyHouseProxy(final BuyHouse buyHouse) {
        this.buyHouse = buyHouse;
    }

    @Override
    public void buyHouse() {
        System.out.println("买房前准备");
        buyHouse.buyHouse();
        System.out.println("买房后装修");
    }
}

package com.opk.proxy;

public class ProxyTest {
    public static void main(String[] args) {
        BuyHouse buyHouse=new BuyHouseImpl();
        buyHouse.buyHouse();
        BuyHouseProxy buyHouseProxy=new BuyHouseProxy(buyHouse);
        buyHouseProxy.buyHouse();
    }
}

测试结果：

 

 动态代理的实现

1、使用本地方法实现动态代理

package com.opk.proxy;

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

public class DynamicProxyHandler implements InvocationHandler {

    private Object object;

    public DynamicProxyHandler(Object object) {
        this.object = object;
    }

    @Override
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        System.out.println("买房前准备");
        Object result = method.invoke(object, args);
        System.out.println("买房后装修");
        return result;
    }
}

package com.opk.proxy;

import java.lang.reflect.Proxy;

public class DynamicProxyTest {
    public static void main(String[] args) {
        BuyHouse buyHouse = new BuyHouseImpl();
        BuyHouse proxyBuyHouse = (BuyHouse) Proxy.newProxyInstance(BuyHouse.class.getClassLoader(), new
                Class[]{BuyHouse.class}, new DynamicProxyHandler(buyHouse));
        proxyBuyHouse.buyHouse();
    }
}

测试结果：

 

 

2、使用cglib实现动态代理

package com.opk.proxy;

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

import java.lang.reflect.Method;

public class CglibProxy implements MethodInterceptor {

    private Object target;

    public Object getInstance(final Object target)
    {
        this.target=target;
        Enhancer enhancer=new Enhancer();
        enhancer.setSuperclass(this.target.getClass());
        enhancer.setCallback(this);
        return enhancer.create();
    }

    @Override
    public Object intercept(Object o, Method method, Object[] objects, MethodProxy methodProxy) throws Throwable {
        System.out.println("买房前准备");
        Object invoke = methodProxy.invokeSuper(o, objects);
        System.out.println("买房后装修");
        return invoke;
    }
}

package com.opk.proxy;

public class CglibProxyTest {
    public static void main(String[] args) {
       BuyHouse buyHouse=new BuyHouseImpl();
       CglibProxy cglibProxy=new CglibProxy();
        BuyHouseImpl instance = (BuyHouseImpl) cglibProxy.getInstance(buyHouse);
        instance.buyHouse();
    }
}

测试结果：

 

 总结：cglib实现动态代理效率会比本地方法高，但是创建对象频繁，如果是单例对象使用cglib实现动态代理，反之，则使用java的本地方法

来源：https://www.cnblogs.com/mingyuan1031/p/11551393.html