接上文，“websocket协议简析”。分享一下基于jetty9实现java版的webcoket服务端和客户端demo。
没有理论，话不多说，代码奉上。
准备工作：
新建maven工程，pom文件引入：

          <dependency>
            <groupId>org.eclipse.jetty.websocket</groupId>
            <artifactId>websocket-client</artifactId>
            <version>9.4.6.v20170531</version>
        </dependency>
        <dependency>
            <groupId>org.eclipse.jetty.websocket</groupId>
            <artifactId>websocket-server</artifactId>
            <version>9.4.6.v20170531</version>
        </dependency>
        <dependency>
            <groupId>org.eclipse.jetty.websocket</groupId>
            <artifactId>websocket-api</artifactId>
            <version>9.4.6.v20170531</version>
    </dependency>

服务端实现：
服务端启动类：

package jasonleewebsocket.websocket.server;

import org.eclipse.jetty.server.Server;
import org.eclipse.jetty.server.handler.ContextHandler;
import org.eclipse.jetty.websocket.server.WebSocketHandler;
import org.eclipse.jetty.websocket.servlet.WebSocketServletFactory;

public class WebSocketServerTest{
       public static void main(String args[]) 
        { 
            Server server = new Server(7778); 
            WebSocketHandler  wsHandler = new WebSocketHandler(){ 
                @Override 
                public void configure(WebSocketServletFactory factory) 
                { 
                    //注册自定义事件监听器
                    factory.register(MyEchoSocket.class); 
                } 
            }; 
            ContextHandler context = new ContextHandler(); 
            context.setContextPath("/echo"); 
            context.setHandler(wsHandler); 
            
            server.setHandler(wsHandler); 
            try 
            { 
                server.start(); 
                server.join(); 
            } 
            catch (Exception e) 
            { 
                e.printStackTrace(); 
            } 
        } 
}

自定义监听类：

package jasonleewebsocket.websocket.server;

import java.io.IOException;
import java.nio.ByteBuffer;
import java.util.Collections;
import java.util.HashSet;
import java.util.Set;

import org.eclipse.jetty.websocket.api.Session;
import org.eclipse.jetty.websocket.api.WebSocketListener;
import org.eclipse.jetty.websocket.api.WriteCallback;

public class MyEchoSocket implements WebSocketListener{
    //维持session
    private static final Set< Session > sessions = 
            Collections.synchronizedSet( new HashSet< Session >() );
    private Session session;
    
    //连接关闭，移除session列表
    public void onWebSocketClose(int statusCode, String reason) {
        System.out.println(reason);
        sessions.remove(this.session);
        this.session = null;
    }

    //建立连接后保存session
    public void onWebSocketConnect(Session session) {
        this.session = session;
        System.out.println(session.isOpen());
        sessions.add(session);
    }
    
    //错误处理
    public void onWebSocketError(Throwable cause) {
        System.out.println(cause.getMessage());
        
    }

    //接收字符串类型消息，并通知所有客户端
    public void onWebSocketBinary(byte[] payload, int offset, int len) {
        System.out.println("WebSocketBinary:"+new String(payload));
        for(final Session session : sessions){
            session.getRemote().sendBytes(ByteBuffer.wrap(payload), new WriteCallback() {
                //回调处理发送是否成功
                public void writeSuccess() {
                    System.out.println("success");
                }
                
                public void writeFailed(Throwable x) {
                    System.out.println("senderror:"+x.getMessage());
                }
            });
        }
    }

    //接收字符串类型消息，并转发给所有客户端
    public void onWebSocketText(String message) {
        System.out.println("text message:"+message);
        try {
            for(final Session session : sessions){
                session.getRemote().sendString("server to convert text:"+message);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

客户端实现：
客户端启动类：

package jasonleewebsocket.websocket.client;

import java.net.URI;
import java.util.concurrent.TimeUnit;

import org.eclipse.jetty.websocket.client.ClientUpgradeRequest;
import org.eclipse.jetty.websocket.client.WebSocketClient;

public class SimpleEchoClient
{
    public static void main(String[] args)
    {
         String destUri = "ws://localhost:7778/echo";
        if (args.length > 0)
        {
            destUri = args[0];
        }

        WebSocketClient client = new WebSocketClient();
        SimpleEchoSocket socket = new SimpleEchoSocket();
        try
        {
            client.start();

            URI echoUri = new URI(destUri);
            ClientUpgradeRequest request = new ClientUpgradeRequest();
            client.connect(socket,echoUri,request);
            System.out.printf("Connecting to : %s%n",echoUri);
            // wait for closed socket connection.
            socket.awaitClose(500,TimeUnit.SECONDS);
        }
        catch (Throwable t)
        {
            t.printStackTrace();
        }
        finally
        {
            try
            {
                client.stop();
            }
            catch (Exception e)
            {
                e.printStackTrace();
            }
        }
    }
}

客户端监听类：

package jasonleewebsocket.websocket.client;

import java.nio.ByteBuffer;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.TimeUnit;

import org.eclipse.jetty.websocket.api.Session;
import org.eclipse.jetty.websocket.api.annotations.OnWebSocketConnect;
import org.eclipse.jetty.websocket.api.annotations.OnWebSocketMessage;
import org.eclipse.jetty.websocket.api.annotations.WebSocket;

@WebSocket
public class SimpleEchoSocket {

    private final CountDownLatch closeLatch;

    public SimpleEchoSocket() {
        this.closeLatch = new CountDownLatch(1);
    }

    public boolean awaitClose(int duration, TimeUnit unit) throws InterruptedException {
        return this.closeLatch.await(duration, unit);
    }

    @OnWebSocketMessage
    public void onMessage(String msg) {
        System.out.printf("Got msg: %s%n", msg);
    }

    @OnWebSocketMessage
    public void onMessage(byte[] buffer, int offset, int length) {
        System.out.printf("Got msg: %s%n", new String(buffer));
    }

    @OnWebSocketConnect
    public void onConnect(Session session) {
        System.out.printf("Got connect: %s%n", session);
        try {
            session.getRemote().sendBytes(ByteBuffer.wrap("test byte".getBytes()));
            session.getRemote().sendString("456");
        } catch (Throwable t) {
            t.printStackTrace();
        }
    }
}