运行环境：jdk8 tomcat8 ??无须其他jar包。package com.reach.socketController;import java.io.IOException;import java.util.HashMap;import java.util.Map;import java.util.concurrent.CopyOnWriteArraySet;import javax.annotation.Resource;import javax.websocket.OnClose;import javax.websocket.OnError;import javax.websocket.OnMessage;import javax.websocket.OnOpen;import javax.websocket.Session;import javax.websocket.server.PathParam;import javax.websocket.server.ServerEndpoint;@ServerEndpoint(value ="/newwebsocket/{userId}")public class Webcomment { ???@Resource ???private Webcomment webcomment; ???????//静态变量，用来记录当前在线连接数。应该把它设计成线程安全的。 ???private static int onlineCount = 0; ???//concurrent包的线程安全Set，用来存放每个客户端对应的MyWebSocket对象。若要实现服务端与单一客户端通信的话，可以使用Map来存放，其中Key可以为用户标识 ???private static CopyOnWriteArraySet<Webcomment> webSocketSet = new CopyOnWriteArraySet<Webcomment>(); ? //线程安全的Map ?????private static ConcurrentHashMap<String,Session> webSocketMap = new ConcurrentHashMap<String,Session>();//建立连接的方法 ???@OnOpen ???public void onOpen(Session session,@PathParam("userId")String ?userId){ ???????/*获取从/websocket开始的整条链接，用于获取userId？***=***的参数 ???????String uri = session.getRequestURI().toString();*/ ???webSocketMap.put(userId, session); ???addOnlineCount(); //在线数加 ???System.out.println(userId+"进入聊天室"); ???System.out.println("有新连接加入！当前在线人数为" + getOnlineCount()); ???} ???????/** ???* 连接关闭调用的方法 ???*/ ???@OnClose ???public void onClose(Session session){ ???Map<String, String> map = session.getPathParameters(); ???webSocketMap.remove(map.get("userId")); //从set中删除 ???for(String user:webSocketMap.keySet()){ ???System.out.println(user); ???} ???subOnlineCount(); //在线数减 ???System.out.println("有一连接关闭！当前在线人数为" + getOnlineCount()); ???} ???????/** ???* 收到客户端消息后调用的方法 ???* @param message 客户端发送过来的消息 ???* @param session 可选的参数 ???*/ ???@OnMessage ???public void onMessage(String message, Session session) { ???System.out.println("来自客户端的消息:" + message); ???//获取用户ID ???Map<String, String> map = session.getPathParameters(); ???String userId = map.get("userId"); ???for(String user:webSocketMap.keySet()){ ???????try { ???????????sendMessage(user+"你好，我是"+userId+" ??"+message,webSocketMap.get(user)); ???????} catch (IOException e) { ???????????e.printStackTrace(); ???????} ???} ???} ???????/** ???* 发生错误时调用 ???* @param session ???* @param error ???*/ ???@OnError ???public void onError(Session session, Throwable error){ ???System.out.println("发生错误"); ???error.printStackTrace(); ???} ???????public void sendMessage(String message,Session session) throws IOException{ ???????if(session.isOpen()){ ???????session.getAsyncRemote().sendText(message); ???????} ???????//this.session.getAsyncRemote().sendText(message); ???????} ???????????????public static synchronized int getOnlineCount() { ???????return onlineCount; ???????} ???public static synchronized void addOnlineCount() { ???????Webcomment.onlineCount++; ???????} ???public static synchronized void subOnlineCount() { ???????Webcomment.onlineCount--; ???????}}html代码，可以单独建立html，无须放在项目中
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"> <head> ?<title> new document </title> ?<meta name="generator" content="editplus" /> ?<meta name="author" content="" /> ?<meta name="keywords" content="" /> ?<meta name="description" content="" /> ?<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> ?<script src="jquery-1.8.3.min.js" type="text/javascript"></script> </head> <body> ?<center>Welcome<br/><input id="text" type="text"/><button onclick="send()">发送消息</button><hr/><button onclick="closeWebSocket()">关闭WebSocket连接</button><hr/><div id="message"></div> </body> <script type="text/javascript">var websocket = null;//判断当前浏览器是否支持WebSocketif (‘WebSocket‘ in window) {alert(‘当前浏览器支持 websocket‘);websocket = new WebSocket("ws://localhost:8080/Y-websocket/newwebsocket/234");}else {alert(‘当前浏览器 Not support websocket‘)}//连接发生错误的回调方法websocket.onerror = function () {setMessageInnerHTML("WebSocket连接发生错误");};//连接成功建立的回调方法websocket.onopen = function () {setMessageInnerHTML("WebSocket连接成功");}//接收到消息的回调方法websocket.onmessage = function (event) {setMessageInnerHTML(event.data);}//连接关闭的回调方法websocket.onclose = function () {setMessageInnerHTML("WebSocket连接关闭");}//监听窗口关闭事件，当窗口关闭时，主动去关闭websocket连接，防止连接还没断开就关闭窗口，server端会抛异常。window.onbeforeunload = function () {closeWebSocket();}//将消息显示在网页上function setMessageInnerHTML(innerHTML) {document.getElementById(‘message‘).innerHTML += innerHTML + ‘<br/>‘;}//关闭WebSocket连接function closeWebSocket() {websocket.close();}//发送消息function send() {var message = document.getElementById(‘text‘).value;websocket.send(message);}</script></html>友情提示： 向客户端发送信息 sendText（）是用来传输字符串的，有一个sendObject（）方法可以通过转码器发送javabean。
但是这里我们不推荐，因为非常麻烦。最简单的办法，就是把要发送的bean转成json字符串。 bean转json
然后在页面将接收的json字符串转成json：JSON.parse(event.data)
WebSocket教程(二)
原文地址：http://www.cnblogs.com/longqingyang/p/7929548.html