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：
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);
}
}
} 
