动态代理proxy

动态代理proxy

1. People 接口

package com.bors.proxy;

public interface People {

    public void findWife();
}

2. XiaoMing implements People

package com.bors.proxy;

public class XiaoMing implements People{

    //结婚之前，需要小明父母帮忙找对象

    @Override
    public void findWife() {
        System.out.println("我是小明，我是个单身狗，我想找个女朋友娶回家！");
    }

    //结婚后，需要小明父母帮忙带孩子
}

3. Parent implements InvocationHandler

package com.bors.proxy;

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

// 增强，advice
public class Parent implements InvocationHandler {
    private People people;

    public Parent(People people) {
        this.people = people;
    }

    @Override
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        before();

        method.invoke(people, args);

        after();
        return null;
    }

    // 封版方法findWife之前执行的方法
    private void before() {
        System.out.println("====================我们是小明父母，我们拿着小明的个人介绍，帮小明找对象");
    }

    // 封版方法findWife之后执行的方法
    private void after() {
        System.out.println("====================我们是小明父母，我们在小明结婚后帮小明带孩子");
    }

}

 4. Test 

public class AppTest {

    @Test
    public void Test1() {
        // proxy代理实例，是对被代理对象起增强作用
        People proxyobj = (People) Proxy.newProxyInstance(Test.class.getClassLoader(),
                new Class<?>[]{People.class}, new Parent(new XiaoMing()));

        createProxyClassFile();

        proxyobj.findWife();
    }

    // 生成代理实例$Proxy2的字节码文件
    public static void createProxyClassFile() {
        byte[] $Proxy2s = ProxyGenerator.generateProxyClass("$Proxy2", new Class[]{People.class});

        try {
            FileOutputStream fileOutputStream = new FileOutputStream("$Proxy2.class");
            fileOutputStream.write($Proxy2s);
            fileOutputStream.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

5. $Proxy2 extends Proxy implements People 

public final class $Proxy2 extends Proxy implements People {
    private static Method m1;
    private static Method m2;
    private static Method m3;
    private static Method m0;

    public $Proxy2(InvocationHandler var1) throws  {
        super(var1);
    }

    public final boolean equals(Object var1) throws  {
        try {
            return (Boolean)super.h.invoke(this, m1, new Object[]{var1});
        } catch (RuntimeException | Error var3) {
            throw var3;
        } catch (Throwable var4) {
            throw new UndeclaredThrowableException(var4);
        }
    }

    public final String toString() throws  {
        try {
            return (String)super.h.invoke(this, m2, (Object[])null);
        } catch (RuntimeException | Error var2) {
            throw var2;
        } catch (Throwable var3) {
            throw new UndeclaredThrowableException(var3);
        }
    }

    public final void findWife() throws  {
        try {
            super.h.invoke(this, m3, (Object[])null);
        } catch (RuntimeException | Error var2) {
            throw var2;
        } catch (Throwable var3) {
            throw new UndeclaredThrowableException(var3);
        }
    }

    public final int hashCode() throws  {
        try {
            return (Integer)super.h.invoke(this, m0, (Object[])null);
        } catch (RuntimeException | Error var2) {
            throw var2;
        } catch (Throwable var3) {
            throw new UndeclaredThrowableException(var3);
        }
    }

    static {
        try {
            m1 = Class.forName("java.lang.Object").getMethod("equals", Class.forName("java.lang.Object"));
            m2 = Class.forName("java.lang.Object").getMethod("toString");
            m3 = Class.forName("com.bors.proxy.People").getMethod("findWife");
            m0 = Class.forName("java.lang.Object").getMethod("hashCode");
        } catch (NoSuchMethodException var2) {
            throw new NoSuchMethodError(var2.getMessage());
        } catch (ClassNotFoundException var3) {
            throw new NoClassDefFoundError(var3.getMessage());
        }
    }
}

 

 重点：

1、InvocationHandler里面的invoke方法是被谁调用的？？

 

2、Proxy.newProxyInstance()执行过程