简单的RPC框架的实现

本文主要是介绍简单的RPC框架的实现，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

本文转载自阿里RPC框架DUBBO的作者粱老师的博客：http://javatar.iteye.com/blog/1123915

通过简单的几行代码就实现了一个RPC框架，对学习其他的RPC框架真的很有帮助。

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;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 IllegalAccessException("service install == null");}if (port <= 0 || port > 65535) {throw new IllegalAccessException("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() {@Overridepublic void run() {ObjectInputStream input = null;ObjectOutputStream output = null;try {input = new ObjectInputStream(socket.getInputStream());String methodName = input.readUTF();Class<?>[] parameterTypes = (Class<?>[])input.readObject();Object[] arguments = (Object[])input.readObject();output = new ObjectOutputStream(socket.getOutputStream());Method method = service.getClass().getMethod(methodName, parameterTypes);Object result = method.invoke(service, arguments);output.writeObject(result);} catch (Exception e) {e.printStackTrace();} finally {try {if (input != null) {input.close();}if (output != null) {output.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 IllegalAccessException("Interface class == null");}if (!interfaceClass.isInterface()) {throw new IllegalAccessException("The " + interfaceClass.getName() + " must be interface class");}if (host == null || host.length() == 0) {throw new IllegalAccessException("Host == null");}if (port <= 0 || port > 65535) {throw new IllegalAccessException("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() {@Overridepublic Object invoke(Object proxy, Method method, Object[] args)throws Throwable {Object result = null;ObjectOutputStream output = null;ObjectInputStream input = null;try {Socket socket = new Socket(host, port);output = new ObjectOutputStream(socket.getOutputStream());output.writeUTF(method.getName());output.writeObject(method.getParameterTypes());output.writeObject(args);input = new ObjectInputStream(socket.getInputStream());result = input.readObject();} catch (Exception e) {e.printStackTrace();} finally {try {if (input != null) {input.close();}if (output != null) {output.close();}} catch (Exception e) {e.printStackTrace();}}return result;}});}
}

定义服务接口：

package com.alibaba.study.rpc.test;public interface HelloService {String hello(String name, int age);
}

实现服务：

package com.alibaba.study.rpc.test;public class HelloServiceImpl implements HelloService{@Overridepublic String hello(String name, int age) {return "Hello " + name + ", age " + age;}}

暴露服务：

package com.alibaba.study.rpc.test;import com.alibaba.study.rpc.framework.RpcFramework;public class RpcProvider {public static void main(String[] args) throws Exception{HelloService service = new HelloServiceImpl();RpcFramework.export(service, 1234);}
}

引用服务：

package com.alibaba.study.rpc.test;import com.alibaba.study.rpc.framework.RpcFramework;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, i);System.out.println(hello);Thread.sleep(1000);}}
}

运行结果：

总结：

从这个小的Demo我们可以发现，RPC的精髓在于服务端所提供的动态代理，消费者通过接口去调用某个方法，其实最后是通过动态代理来调用到了服务端的真实方法，然而代理中参数，方法，接口的传递是通过TCP作为通讯方式实现而已，如果你有兴趣，还可以用Http进行实现。

2017-11-16补充：

上面的总结总感觉有问题，客户端在调用RPC服务时，客户端有调用服务的接口，而对接口的实现是在服务端进行的，服务端启动，监听某个接口，并将提供的服务（主要是地址+端口+服务）进行注册，你可以注册到内存也可以注册到zookeeper中间件，客户端调用类似于ClientProxy通过动态代理（这段代码是在客户端的），这段代码利用反射将客户端需要调用的服务（接口的字节码、参数、方法）组装成待发送的请求，然后通过网络工具（netty、jetty、mina、selvlet）的客户端经过序列化（Hessian、Jackson、Protostuff）发送到服务端,服务端接收到反序列化然后反射调用，OK

 

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