Java实现最简单的RPC框架

使用Java原生的序列化、动态代理、反射等实现简单的RPC框架。本示例来源于《分布式服务框架》。

示例

• EchoService.java

复制代码public interface EchoService {
    String echo(String ping);
}

• EchoServiceImpl.java

复制代码public class EchoServiceImpl implements EchoService {
    @Override
    public String echo(String ping) {
        return ping != null ? ping + "--> I am OK." : " I am OK.";
    }
}

• RpcExporter.java

复制代码import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.lang.reflect.Method;
import java.net.InetSocketAddress;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.concurrent.Executor;
import java.util.concurrent.Executors;

/**
 * Created by lbd on 2017/11/12.
 */
public class RpcExporter {
    static Executor executor = Executors.newFixedThreadPool(Runtime.getRuntime().availableProcessors());

    public static void exporter(String hostName, int port) throws Exception {
        ServerSocket server = new ServerSocket();
        server.bind(new InetSocketAddress(hostName, port));
        try {
            while (true) {
                executor.execute(new ExporterTask(server.accept()));
            }
        } finally {
            server.close();
        }
    }

    private static class ExporterTask implements Runnable {
        Socket client = null;

        public ExporterTask(Socket client) {
            this.client = client;
        }

        @Override
        public void run() {
            ObjectInputStream input = null;
            ObjectOutputStream output = null;

            try {
                input = new ObjectInputStream(client.getInputStream());
                String interfaceName = input.readUTF();
                Class<?> service = Class.forName(interfaceName);
                String methodName = input.readUTF();
                Class<?>[] parameterTypes = (Class<?>[])input.readObject();
                Object[] arguments = (Object[])input.readObject();
                Method method = service.getMethod(methodName, parameterTypes);
                Object result = method.invoke(service.newInstance(), arguments);
                output = new ObjectOutputStream(client.getOutputStream());
                output.writeObject(result);
            } catch (Exception e) {
                e.printStackTrace();
            } finally {
                if (output != null)
                    try {
                        output.close();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }

                if (input != null)
                    try {
                        input.close();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }

            }
        }
    }
}

• RpcImporter.java

复制代码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.InetSocketAddress;
import java.net.Socket;

/**
 * Created by lbd on 2017/11/12.
 */
public class RpcImporter<S> {
    public S importer(final Class<?> serviceClass, final InetSocketAddress addr) {
        return (S) Proxy.newProxyInstance(serviceClass.getClassLoader(), new Class<?>[]{serviceClass.getInterfaces()[0]},
                new InvocationHandler() {
                    @Override
                    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
                        Socket socket = null;
                        ObjectOutputStream output = null;
                        ObjectInputStream input = null;
                        try {
                            socket = new Socket();
                            socket.connect(addr);
                            output = new ObjectOutputStream(socket.getOutputStream());
                            output.writeUTF(serviceClass.getName());
                            output.writeUTF(method.getName());
                            output.writeObject(method.getParameterTypes());
                            output.writeObject(args);
                            input = new ObjectInputStream(socket.getInputStream());
                            return input.readObject();
                        } finally {
                            if (socket != null)
                                socket.close();
                            if (output != null)
                                output.close();
                            if (input != null)
                                input.close();
                        }
                    }
                });
    }
}

• RpcTest.java

复制代码import java.net.InetSocketAddress;

/**
 * Created by lbd on 2017/11/12.
 */
public class RpcTest {
    public static void main(String[] args) {
        new Thread(new Runnable() {
            @Override
            public void run() {
                try {
                    RpcExporter.exporter("localhost", 7890);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }).start();

        RpcImporter<EchoService> proxyImporter = new RpcImporter<>();
        EchoService echoService = proxyImporter.importer(EchoServiceImpl.class, new InetSocketAddress("localhost", 7890));
        System.out.println(echoService.echo("Are you ok ?"));
    }
}

输出

复制代码Are you ok ?--> I am OK.

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