基於Socket與Netty的RPC實現
前言
RPC的大多數實現方式包括兩類:Socket與Netty,接下來介紹兩種方式基於java的簡單實現。
RPC架構分為三部分:
1)服務提供者,執行在伺服器端,提供服務介面定義與服務實現類。
2)服務中心,執行在伺服器端,負責將本地服務釋出成遠端服務,管理遠端服務,提供給服務消費者使用。
3)服務消費者,執行在客戶端,通過遠端代理物件呼叫遠端服務。
1 Socket
RPC的socket實現是基於TCP/IP協議,它在通訊的兩端各建立一個Socket,從而在通訊的兩端之間形成網路虛擬鏈路。一旦建立了虛擬的網路鏈路,兩端的成員就可以通過虛擬鏈路進行通訊。Java是對基於TCP協議的網路通訊提供了良好的封裝,Java使用Socket物件來代表兩端的通訊埠,並通過Socket產生IO流來進行網路通訊,實現消費者與服務方的通訊。
1.1 Interface
首先介紹介面類中的介面方法:
SayHello.java
public interface SayHello {
String sayHello(String name);
}
Server.java
import java.io.IOException; public interface Server { void stop(); void start() throws IOException; void register(Class serviceInterface, Class impl); boolean isRunning(); int getPort(); }
1.2 Provider
服務端定義介面的具體實現,包括被呼叫方法以及服務中心實現。
SayHelloImpl.java
/**
* @author jhz
* @date 18-8-24 下午8:56
*/
public class SayHelloImpl implements SayHello{
@Override
public String sayHello(String name) {
return name;
}
}
ServerImpl.java
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.HashMap; import java.util.concurrent.ExecutorService; import java.util.concurrent.Executors; /** * @author jhz * @date 18-8-24 下午10:00 */ public class ServerImpl implements Server { private static ExecutorService executor = Executors.newFixedThreadPool(Runtime.getRuntime().availableProcessors()); private static final HashMap<String, Class> serviceRegistry = new HashMap<String, Class>(); private static boolean isRunning = false; private static int port; public ServerImpl(int port) { this.port = port; } public void stop() { isRunning = false; executor.shutdown(); } public void start() throws IOException { ServerSocket server = new ServerSocket(); server.bind(new InetSocketAddress(port)); System.out.println("start server"); try { while (true) { // 1.監聽客戶端的TCP連線,接到TCP連線後將其封裝成task,由執行緒池執行 executor.execute(new ServiceTask(server.accept())); } } finally { server.close(); } } public void register(Class serviceInterface, Class impl) { serviceRegistry.put(serviceInterface.getName(), impl); } public boolean isRunning() { return isRunning; } public int getPort() { return port; } private static class ServiceTask implements Runnable { Socket clent = null; public ServiceTask(Socket client) { this.clent = client; } public void run() { ObjectInputStream input = null; ObjectOutputStream output = null; try { // 2.將客戶端傳送的碼流反序列化成物件,反射呼叫服務實現者,獲取執行結果 input = new ObjectInputStream(clent.getInputStream()); String serviceName = input.readUTF(); String methodName = input.readUTF(); Class<?>[] parameterTypes = (Class<?>[]) input.readObject(); Object[] arguments = (Object[]) input.readObject(); Class serviceClass = serviceRegistry.get(serviceName); if (serviceClass == null) { throw new ClassNotFoundException(serviceName + " not found"); } Method method = serviceClass.getMethod(methodName, parameterTypes); Object result = method.invoke(serviceClass.newInstance(), arguments); // 3.將執行結果反序列化,通過socket傳送給客戶端 output = new ObjectOutputStream(clent.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(); } } if (clent != null) { try { clent.close(); } catch (IOException e) { e.printStackTrace(); } } } } } }
ProviderRunner.java(服務端啟動)
import java.io.IOException;
/**
* @author jhz
* @date 18-8-24 下午10:40
*/
public class ProviderRunner {
public static void main(String[] args) {
new Thread(new Runnable() {
public void run() {
try {
Server serviceServer = new ServerImpl(8088);
serviceServer.register(SayHello.class, SayHelloImpl.class);
serviceServer.start();
} catch (IOException e) {
e.printStackTrace();
}
}
}).start();
}
}
1.3 Consumer
RPCClient.java(客戶端代理類)
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;
/**
* @author jhz
* @date 18-8-24 下午10:10
*/
public class RPCClient {
public static <T> T getRemoteProxyObj(final Class<?> serviceInterface, final InetSocketAddress addr) {
// 1.將本地的介面呼叫轉換成JDK的動態代理,在動態代理中實現介面的遠端呼叫
return (T) Proxy.newProxyInstance(serviceInterface.getClassLoader(), new Class<?>[]{serviceInterface},
new InvocationHandler() {
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
Socket socket = null;
ObjectOutputStream output = null;
ObjectInputStream input = null;
try {
// 2.建立Socket客戶端,根據指定地址連線遠端服務提供者
socket = new Socket();
socket.connect(addr);
// 3.將遠端服務呼叫所需的介面類、方法名、引數列表等編碼後傳送給服務提供者
output = new ObjectOutputStream(socket.getOutputStream());
output.writeUTF(serviceInterface.getName());
output.writeUTF(method.getName());
output.writeObject(method.getParameterTypes());
output.writeObject(args);
// 4.同步阻塞等待伺服器返回應答,獲取應答後返回
input = new ObjectInputStream(socket.getInputStream());
return input.readObject();
} finally {
if (socket != null) socket.close();
if (output != null) output.close();
if (input != null) input.close();
}
}
});
}
}
可以看到遠端的呼叫是在動態處理器中的invoke()方法(匿名類中的invoke)中實現的,且是同步阻塞的實現方式,當客戶端發起呼叫時,在invoke()中發起建立socket連線,等待服務端返回呼叫結果。
SocketRunner.java(呼叫類)
import java.io.IOException;
import java.net.InetSocketAddress;
/**
* @author jhz
* @date 18-8-24 下午10:19
*/
public class SocketRunner {
public static void main(String[] args) throws IOException {
SayHello service = RPCClient.getRemoteProxyObj(SayHello.class, new InetSocketAddress("localhost", 8088));
System.out.println(service.sayHello("hello jhz!"));
}
}
執行結果
首先啟動服務端
再啟動客戶端:
2 Netty
接著我們使用Netty來代替這種BIO的實現:
2.1 Interface
介面類只需要定義介面方法(SayHello),服務端中的實現方法也不用變
2.2 Provider
NettyServer.java(Netty服務端)
import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import io.netty.handler.codec.string.StringDecoder;
import io.netty.handler.codec.string.StringEncoder;
/**
* @author jhz
* @date 18-8-24 下午10:48
*/
public class NettyServer {
public static void startServer(String hostName, int port) {
try {
ServerBootstrap bootstrap = new ServerBootstrap();
NioEventLoopGroup eventLoopGroup = new NioEventLoopGroup();
bootstrap.group(eventLoopGroup)
.channel(NioServerSocketChannel.class)
.childHandler(new ChannelInitializer<SocketChannel>() {
@Override
protected void initChannel(SocketChannel ch) throws Exception {
ChannelPipeline p = ch.pipeline();
p.addLast(new StringDecoder());
p.addLast(new StringEncoder());
p.addLast(new HelloServerHandler());
}
});
bootstrap.bind(hostName, port).sync();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
在NettyServer中定義ServerBootStrap,並新增自定義的handler,具體的實現如下:
HelloServerHandler.java
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
/**
* @author jhz
* @date 18-8-26 上午12:40
*/
public class HelloServerHandler extends ChannelInboundHandlerAdapter {
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) {
// 如何符合約定,則呼叫本地方法,返回資料
if (msg.toString().startsWith("SayHello")) {
String result = new SayHelloImpl()
.sayHello(msg.toString().substring(msg.toString().lastIndexOf("#") + 1));
ctx.writeAndFlush(result);
}
}
}
該類重寫channelRead以實現對channel中訊息的過濾以及具體方法的呼叫。
NettyServerStarter.java
/**
* @author jhz
* @date 18-8-26 上午12:23
*/
public class NettyServerStarter {
public static void main(String[] args) {
NettyServer.startServer("localhost", 8088);
System.out.println("Netty Server Start!");
}
}
2.2 Consumer
同樣,我們需要建立客戶端代理類
RPCConsumer.java
import io.netty.bootstrap.Bootstrap;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelOption;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioSocketChannel;
import io.netty.handler.codec.string.StringDecoder;
import io.netty.handler.codec.string.StringEncoder;
import java.lang.reflect.Proxy;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
/**
* @author jhz
* @date 18-8-26 上午12:19
*/
public class RPCConsumer {
private static ExecutorService executor = Executors
.newFixedThreadPool(Runtime.getRuntime().availableProcessors());
private static SayHelloHandler client;
/**
* 建立一個代理物件
*/
public Object createProxy(final Class<?> serviceClass,
final String providerName) {
return Proxy.newProxyInstance(Thread.currentThread().getContextClassLoader(),
new Class<?>[]{serviceClass}, (proxy, method, args) -> {
if (client == null) {
initClient();
}
// 設定引數
client.setPara(providerName + args[0]);
return executor.submit(client).get();
});
}
/**
* 初始化客戶端
*/
private static void initClient() {
client = new SayHelloHandler();
EventLoopGroup group = new NioEventLoopGroup();
Bootstrap b = new Bootstrap();
b.group(group)
.channel(NioSocketChannel.class)
.option(ChannelOption.TCP_NODELAY, true)
.handler(new ChannelInitializer<SocketChannel>() {
@Override
public void initChannel(SocketChannel ch) throws Exception {
ChannelPipeline p = ch.pipeline();
p.addLast(new StringDecoder());
p.addLast(new StringEncoder());
p.addLast(client);
}
});
try {
b.connect("localhost", 8088).sync();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
在代理中實現客戶端的初始化,定義ClientBootStrap並新增客戶端的自定義handler(SayHelloHandler),這個handler同時還能在收到回覆後完成callback,SayHelloHandler的具體實現如下。
ClientHandler.java
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
import java.util.concurrent.Callable;
public class SayHelloHandler extends ChannelInboundHandlerAdapter implements Callable {
private ChannelHandlerContext context;
private String result;
private String para;
@Override
public void channelActive(ChannelHandlerContext ctx) {
context = ctx;
}
/**
* 收到服務端資料,喚醒等待執行緒
*/
@Override
public synchronized void channelRead(ChannelHandlerContext ctx, Object msg) {
result = msg.toString();
notify();
}
/**
* 寫出資料,開始等待喚醒
*/
@Override
public synchronized Object call() throws InterruptedException {
context.writeAndFlush(para);
wait();
return result;
}
void setPara(String para) {
this.para = para;
}
}
定義了ChannelHandlerContext context:快取ctx,可以用於下次使用,整個流程如下,客戶端發起呼叫->呼叫call()方法,將請求訊息寫入channel並等待喚醒->收到服務端返回的訊息呼叫channelRead()並喚醒call上等待的執行緒,返回結果。
ClientBootStrap.java(客戶端測試類)
/**
* @author jhz
* @date 18-8-26 上午12:12
*/
public class ClientBootStrap {
public static final String providerName = "SayHello#sayHello#";
public static void main(String[] args) throws InterruptedException {
RPCConsumer consumer = new RPCConsumer();
// 建立一個代理物件
SayHello service = (SayHello) consumer
.createProxy(SayHello.class, providerName);
System.out.println(service.sayHello("hello jhz"));
}
}
測試結果
啟動Netty服務端:
客戶端呼叫:
採用Netty實現的RPC是執行緒級別的阻塞,並不會影響到其他的執行緒。