手写动态代理

手写动态代理

MyInvocationHandler:

package com.lipengyu.util;

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

import com.lipengyu.service.Person;

public class MyInvocationHandler implements InvocationHandler {

    private Person target;

    public MyInvocationHandler(Person target) {
        this.target = target;
    }

    @Override
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        wash();
        Object value = method.invoke(target, args);
        return value;
    }

    private void wash() {
        System.out.println("洗手..");
    }
}

ProxyFactory :

package com.lipengyu.util;

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

import com.lipengyu.service.Person;

public class ProxyFactory {

    public static Person build(Class clazz) throws Exception {
        Person person = (Person)clazz.newInstance();
        InvocationHandler invocationHandler = new MyInvocationHandler(person);
        return (Person) Proxy.newProxyInstance(person.getClass().getClassLoader(), person.getClass().getInterfaces(),invocationHandler);
    }
}

LiPengyu:

package com.lipengyu.service;

public class LiPengyu implements Person {

    @Override
    public void eat() {
        System.out.println("我吃饭了....");
    }
}

Person :

package com.lipengyu.service;

public interface Person {

    void eat();
}

TestMain :

package com.lipengyu.util;

import java.io.FileOutputStream;
import java.io.IOException;

import com.lipengyu.com.lipengyu.util.ProxyFactory;
import com.lipengyu.service.Person;
import com.lipengyu.service.LiPengyu;

import sun.misc.ProxyGenerator;

public class TestMain {
    public static void main(String[] args) throws Exception {
        Person person = ProxyFactory.build(LiPengyu.class);
        person.eat();
        createProxyClassFile(person.getClass());
    }

    private static void createProxyClassFile(Class c) {
        byte[] data = ProxyGenerator.generateProxyClass("$Proxy()", new Class[]{c});
        try {
            FileOutputStream fileOutputStream = new FileOutputStream("$Proxy0.class");
            fileOutputStream.write(data);
            fileOutputStream.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

}