package com.zhang;

import java.lang.reflect.InvocationHandler;

import java.lang.reflect.Method;

import java.lang.reflect.Proxy;

interface HelloSerivce {

    void sayHello();

    void sayHi();

}

interface FuckService {

    void fuck();

}

class HelloServiceImpl implements HelloSerivce {

    @Override

    public void sayHello() {

        System.out.println("hello zhang");

    }

    @Override

    public void sayHi() {

        System.out.println("hi zhang");

    }

} 

public class InvocationHandler_Test {

    public static void main(String[] args) {

        class MyInvocationHandler implements InvocationHandler {

            private Object obj;

            public MyInvocationHandler(Object obj) {

                this.obj = obj;

            }

            //拦截方法

            @Override

            public Object invoke(Object proxy, Method method, Object[] args)

                    throws Throwable {

                if ("sayHello".equals(method.getName())) {

                    System.out.println("拦截sayHello");

                } else if("sayHi".equals(method.getName())) {

                    System.out.println("拦截sayHi");

                }

                //调用原始方法

                method.invoke(obj, args);

                return null;

            }

            @Override

            public String toString() {

                return "MyInvocationHandler:" + System.currentTimeMillis();

            }

        } 

        HelloSerivce helloSerivceImpl = new HelloServiceImpl();

        MyInvocationHandler myInvocationHandler = new MyInvocationHandler(helloSerivceImpl);

        //生成代理

        Class<?>[] src = HelloServiceImpl.class.getInterfaces();

        Class<?>[] dest = new Class<?>[src.length + 1];

        System.arraycopy(src, 0, dest, 0, src.length);

        dest[src.length] = FuckService.class;

        HelloSerivce proxyInstance = (HelloSerivce)Proxy.newProxyInstance(HelloServiceImpl.class.getClassLoader(),

                dest, myInvocationHandler);

        proxyInstance.sayHello();

        proxyInstance.sayHi();

        System.out.println(proxyInstance instanceof FuckService);

        FuckService fService = (FuckService)proxyInstance;

        //报错

        fService.fuck();

    }

}

public class InvokerInvocationHandler implements InvocationHandler {

    private final Invoker<?> invoker;

    public InvokerInvocationHandler(Invoker<?> handler){

        this.invoker = handler;

    }

    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {

        String methodName = method.getName();

        Class<?>[] parameterTypes = method.getParameterTypes();

        //如果是Object的方法，直接调用原生对象的方法

        if (method.getDeclaringClass() == Object.class) {

            return method.invoke(invoker, args);

        }

        //下面的判断其实是冗余的

        if ("toString".equals(methodName) && parameterTypes.length == 0) {

            return invoker.toString();

        }

        if ("hashCode".equals(methodName) && parameterTypes.length == 0) {

            return invoker.hashCode();

        }

        if ("equals".equals(methodName) && parameterTypes.length == 1) {

            return invoker.equals(args[0]);

        }

        //剩下的就需要发送请求给provider了

        return invoker.invoke(new RpcInvocation(method, args)).recreate();

    }

}

//JdkProxyFactory

@SuppressWarnings("unchecked")

public <T> T getProxy(Invoker<T> invoker, Class<?>[] interfaces) {

    return (T) Proxy.newProxyInstance(Thread.currentThread().getContextClassLoader(), 
              interfaces, new InvokerInvocationHandler(invoker));

}

//JavassistProxyFactory

@SuppressWarnings("unchecked")

public <T> T getProxy(Invoker<T> invoker, Class<?>[] interfaces) {

    return (T) Proxy.getProxy(interfaces).newInstance(new InvokerInvocationHandler(invoker));

} 

public interface HelloService {

    String sayHello();

}

class com.alibaba.dubbo.common.bytecode.proxy0 implements

    com.alibaba.dubbo.rpc.service.EchoService, com.zhang.HelloService {

    public <init>(java.lang.reflect.InvocationHandler arg0){

        handler=$1;

    }

    public static java.lang.reflect.Method[] methods;

    private java.lang.reflect.InvocationHandler handler;

    public java.lang.String sayHello(){

        Object[] args = new Object[0];

        //handler是InvokerInvocationHandler对象

        Object ret = handler.invoke(this, methods[0], args);

        return (java.lang.String)ret;

    }

    public java.lang.Object $echo(java.lang.Object arg0){

        Object[] args = new Object[1];

        args[0] = ($w)$1;

        Object ret = handler.invoke(this, methods[1], args);

        return (java.lang.Object)ret;

    }

}