分布式服务架构学习（一）：实现自己的RPC框架（采用Java Socket）

RPC实现原理图：

1、Service API对应服务接口。

HelloService.java代码如下：

package com.shan.rpc.service;

public interface HelloService {
	public String sayHello(String content);
}

2、Service Impl对应服务接口的实现：

HelloServiceImpl.java代码如下：

package com.shan.rpc.service.impl;

import com.shan.rpc.service.HelloService;

public class HelloServiceImpl implements HelloService {
	public String sayHello(String content) {
		return "hello," + content;
	}
}

3、Consumer Proxy 角色对应服务消费者代理类。通过实现服务接口的动态代理对象获得服务接口的动态代理实例Proxy.newProxyInstance，通过实现InvocationHandler接口中的invoke方法来完成远程RPC的调用。具体通过输出流将调用接口的方法及参数写入Socket，发起远程调用。之后通过Java对象输入流从Socket获得返回结果。

ConsumerProxy.java代码如下：

package com.shan.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.Socket;

public class ConsumerProxy {
	
	/**
	 * @Title: consume
	 * @Description：服务消费代理
	 * @author fuss
	 * @date 2018年7月12日
	 * @param interfaceClass
	 * @param host
	 * @param port
	 * @return
	 * @throws Exception
	 */
	public static <T> T consume(final Class<T> interfaceClass, final String host, final int port) throws Exception {
		return (T) Proxy.newProxyInstance(interfaceClass.getClassLoader(), new Class<?>[]{interfaceClass}, new InvocationHandler() {
			@Override
			public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
				Socket socket = new Socket(host, port);
				try {
					ObjectOutputStream output = new ObjectOutputStream(socket.getOutputStream());
					try {
						output.writeUTF(method.getName());
						output.writeObject(args);
						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();
				}
			}
		});
	}
	
}

4、Provider Reflect角色对应服务发布实现。通过输入流从Socket中按照ConsumerProxy的写入顺序注意获取调动方法

名称及方法参数，通过MethodUtils.invokeExactMethod对服务实现类发起反射调用，将调用结果写入Socket返回给对方。

ProviderReflect.java代码如下：

package com.shan.rpc.framework;

import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

import org.apache.commons.lang3.reflect.MethodUtils;

public class ProviderReflect {
	
	private static final ExecutorService EXECUTOR_SERVICE = Executors.newCachedThreadPool();
	
	/**
	 * @Title: provider
	 * @Description：服务发布
	 * @author fuss
	 * @date 2018年7月12日
	 * @param service
	 * @param port
	 * @throws Exception
	 */
	public static void provider(final Object service, int port) throws Exception {
		ServerSocket serverSocket = new ServerSocket(port);
		while (true) {
			final Socket socket = serverSocket.accept();
			EXECUTOR_SERVICE.execute(new Runnable() {
				@Override
				public void run() {
					try {
						ObjectInputStream input = new ObjectInputStream(socket.getInputStream());
						try {
							try {
								String methodName = input.readUTF();//方法名称
								Object[] args = (Object[]) input.readObject();//方法参数
								ObjectOutputStream output = new ObjectOutputStream(socket.getOutputStream());
								try {
									Object result = MethodUtils.invokeExactMethod(service, methodName, args);
									output.writeObject(result);
								} catch (Throwable t) {
									output.writeObject(t);
								} finally {
									output.close();
								}
							} catch (Exception e) {
								e.printStackTrace();
							} finally {
								input.close();
							}
						} finally {
							socket.close();
						}
					} catch (Exception e) {
						e.printStackTrace();
					}
					
				}
			});
		}
	}
	
}

然后写main方法通过ProviderReflect发布服务，代码如下：

package com.shan.rpc.invoke;

import com.shan.rpc.framework.ProviderReflect;
import com.shan.rpc.service.HelloService;
import com.shan.rpc.service.impl.HelloServiceImpl;

public class RpcProviderMain {

	public static void main(String[] args) throws Exception {
		HelloService service = new HelloServiceImpl();
		ProviderReflect.provider(service, 8083);
	}

}

客户端调用远程服务的main方法，代码如下：

package com.shan.rpc.invoke;

import com.shan.rpc.framework.ConsumerProxy;
import com.shan.rpc.service.HelloService;

public class RpcConsumerMain {

	public static void main(String[] args) throws Exception {
		HelloService service = ConsumerProxy.consume(HelloService.class, "127.0.0.1", 8083);
		for (int i = 0; i < 1000; i++) {
			String hello = service.sayHello("fuss_" + i);
			System.out.println(hello);
			Thread.sleep(1000);
		}
	}

}

执行结果如图：