RPC框架几行代码就够了

虽然以前也大概知道rpc的实现原理，也看过部分msgpack的实现，但是对于反射不是很了解。

现在看到一个简单完整的实现，也解决我的以前的另一个疑惑：

http://topic.csdn.net/u/20111028/14/092f98d0-ecdc-48b2-bf8b-317d5071ab6f.html?seed=361547001&r=77648361#r_77648361

不过，还是不明白为什么msgpack只用函数名，没有结合参数列表来识别一个函数，为了和其它语言兼容？

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from：http://javatar.iteye.com/blog/1123915

因为要给百技上实训课，让新同学们自行实现一个简易RPC框架，在准备PPT时，就想写个示例，发现原来一个RPC框架只要一个类，10来分钟就可以写完了，虽然简陋，也晒晒： 

 /*
  * Copyright 2011 Alibaba.com All right reserved. This software is the
  * confidential and proprietary information of Alibaba.com ("Confidential
  * Information"). You shall not disclose such Confidential Information and shall
  * use it only in accordance with the terms of the license agreement you entered
  * into with Alibaba.com.
  */
 package com.alibaba.study.rpc.framework;

 import java.io.ObjectInputStream;
 import java.io.ObjectOutputStream;
 import java.lang.reflect.InvocationHandler;
 import java.lang.reflect.Method;
 import java.lang.reflect.Proxy;
 import java.net.ServerSocket;
 import java.net.Socket;

 /**
  * RpcFramework
  *
  * @author william.liangf
  */
 public class RpcFramework {

     /**
      * 暴露服务
      *
      * @param service 服务实现
      * @param port 服务端口
      * @throws Exception
      */
     public static void export(final Object service, int port) throws Exception {
         if (service == null)
             throw new IllegalArgumentException("service instance == null");
         if (port <= 0 || port > 65535)
             throw new IllegalArgumentException("Invalid port " + port);
         System.out.println("Export service " + service.getClass().getName() + " on port " + port);
         ServerSocket server = new ServerSocket(port);
         for(;;) {
             try {
                 final Socket socket = server.accept();
                 new Thread(new Runnable() {
                     @Override
                     public void run() {
                         try {
                             try {
                                 ObjectInputStream input = new ObjectInputStream(socket.getInputStream());
                                 try {
                                     String methodName = input.readUTF();
                                     Class<?>[] parameterTypes = (Class<?>[])input.readObject();
                                     Object[] arguments = (Object[])input.readObject();
                                     ObjectOutputStream output = new ObjectOutputStream(socket.getOutputStream());
                                     try {
                                         Method method = service.getClass().getMethod(methodName, parameterTypes);
                                         Object result = method.invoke(service, arguments);
                                         output.writeObject(result);
                                     } catch (Throwable t) {
                                         output.writeObject(t);
                                     } finally {
                                         output.close();
                                     }
                                 } finally {
                                     input.close();
                                 }
                             } finally {
                                 socket.close();
                             }
                         } catch (Exception e) {
                             e.printStackTrace();
                         }
                     }
                 }).start();
             } catch (Exception e) {
                 e.printStackTrace();
             }
         }
     }

     /**
      * 引用服务
      *
      * @param <T> 接口泛型
      * @param interfaceClass 接口类型
      * @param host 服务器主机名
      * @param port 服务器端口
      * @return 远程服务
      * @throws Exception
      */
     @SuppressWarnings("unchecked")
     public static <T> T refer(final Class<T> interfaceClass, final String host, final int port) throws Exception {
         if (interfaceClass == null)
             throw new IllegalArgumentException("Interface class == null");
         if (! interfaceClass.isInterface())
             throw new IllegalArgumentException("The " + interfaceClass.getName() + " must be interface class!");
         if (host == null || host.length() == 0)
             throw new IllegalArgumentException("Host == null!");
         if (port <= 0 || port > 65535)
             throw new IllegalArgumentException("Invalid port " + port);
         System.out.println("Get remote service " + interfaceClass.getName() + " from server " + host + ":" + port);
         return (T) Proxy.newProxyInstance(interfaceClass.getClassLoader(), new Class<?>[] {interfaceClass}, new InvocationHandler() {
             public Object invoke(Object proxy, Method method, Object[] arguments) throws Throwable {
                 Socket socket = new Socket(host, port);
                 try {
                     ObjectOutputStream output = new ObjectOutputStream(socket.getOutputStream());
                     try {
                         output.writeUTF(method.getName());
                         output.writeObject(method.getParameterTypes());
                         output.writeObject(arguments);
                         ObjectInputStream input = new ObjectInputStream(socket.getInputStream());
                         try {
                             Object result = input.readObject();
                             if (result instanceof Throwable) {
                                 throw (Throwable) result;
                             }
                             return result;
                         } finally {
                             input.close();
                         }
                     } finally {
                         output.close();
                     }
                 } finally {
                     socket.close();
                 }
             }
         });
     }

 }

用起来也像模像样：

(1) 定义服务接口 

 /*
  * Copyright 2011 Alibaba.com All right reserved. This software is the
  * confidential and proprietary information of Alibaba.com ("Confidential
  * Information"). You shall not disclose such Confidential Information and shall
  * use it only in accordance with the terms of the license agreement you entered
  * into with Alibaba.com.
  */
 package com.alibaba.study.rpc.test;

 /**
  * HelloService
  *
  * @author william.liangf
  */
 public interface HelloService {

     String hello(String name);

 }

(2) 实现服务  

 /*
  * Copyright 2011 Alibaba.com All right reserved. This software is the
  * confidential and proprietary information of Alibaba.com ("Confidential
  * Information"). You shall not disclose such Confidential Information and shall
  * use it only in accordance with the terms of the license agreement you entered
  * into with Alibaba.com.
  */
 package com.alibaba.study.rpc.test;

 /**
  * HelloServiceImpl
  *
  * @author william.liangf
  */
 public class HelloServiceImpl implements HelloService {

     public String hello(String name) {
         return "Hello " + name;
     }

 }

(3) 暴露服务  

 /*
  * Copyright 2011 Alibaba.com All right reserved. This software is the
  * confidential and proprietary information of Alibaba.com ("Confidential
  * Information"). You shall not disclose such Confidential Information and shall
  * use it only in accordance with the terms of the license agreement you entered
  * into with Alibaba.com.
  */
 package com.alibaba.study.rpc.test;

 import com.alibaba.study.rpc.framework.RpcFramework;

 /**
  * RpcProvider
  *
  * @author william.liangf
  */
 public class RpcProvider {

     public static void main(String[] args) throws Exception {
         HelloService service = new HelloServiceImpl();
         RpcFramework.export(service, 1234);
     }

 }

(4) 引用服务  

 /*
  * Copyright 2011 Alibaba.com All right reserved. This software is the
  * confidential and proprietary information of Alibaba.com ("Confidential
  * Information"). You shall not disclose such Confidential Information and shall
  * use it only in accordance with the terms of the license agreement you entered
  * into with Alibaba.com.
  */
 package com.alibaba.study.rpc.test;

 import com.alibaba.study.rpc.framework.RpcFramework;

 /**
  * RpcConsumer
  *
  * @author william.liangf
  */
 public class RpcConsumer {

     public static void main(String[] args) throws Exception {
         HelloService service = RpcFramework.refer(HelloService.class, "127.0.0.1", 1234);
         for (int i = 0; i < Integer.MAX_VALUE; i ++) {
             String hello = service.hello("World" + i);
             System.out.println(hello);
             Thread.sleep(1000);
         }
     }

 }