必要环境：JDK1.7以上，tomcat7.0以上。以下是干货：
1、websocket的jar直接从tomcat运行库里面添加到build path里面。
2、前台聊天页面，通过ws://localhost:8080/newProject/websocketTest与后台建立连接
<%@ page language=\"java\" import=\"java.util.\" pageEncoding=\"UTF-8\"%> <!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\"><html><head> <title>My JSP 'socketChart.jsp' starting page</title><script type=\"text/javascript\" src=\"js/jquery-1.8.2.js\"></script></head> <body>${username}<br/>在线人数:<div id=\"onlineCount\">0</div><br />发送对象:<input id=\"username\" type=\"text\" width=\"50px\"/>内容:<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) {websocket = new WebSocket(\"ws://localhost:8080/newProject/websocketTest\");} 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) {debuggervar messageJson=eval(\"(\"+event.data+\")\");if(messageJson.messageType==\"message\"){setMessageInnerHTML(messageJson.data);}if(messageJson.messageType==\"onlineCount\"){document.getElementById('onlineCount').innerHTML=messageJson.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;var username = document.getElementById('username').value;websocket.send(username+\"@\"+message);document.getElementById('message').innerHTML += message + '<br/>';}</script></html>
3、登录页面，简单的创建一个session会话模拟用户登录用作点对点聊天的唯一标识。
<%@ page language=\"java\" import=\"java.util.\" pageEncoding=\"UTF-8\"%><%String path = request.getContextPath();String basePath = request.getScheme() + \"://\"+ request.getServerName() + \":\" + request.getServerPort()+ path + \"/\";%> <!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\"><html><head><base href=\"<%=basePath%>\"> <title>My JSP 'login.jsp' starting page</title> </head> <body><center><form action=\"chatWebsocket/login.do\" method=\"post\"><table><tr><td>username:</td><td><input type=\"text\" id=\"username\" name=\"username\"/></td></tr><tr><td colspan=\"2\"> <input type=\"submit\" value=\"登录\"/></td></tr></table></form></center></body></html>
4、controller类，模拟登录创建会话，并向socket工具类里面传送登录用户的唯一标识。
package com.test.controller; import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import javax.servlet.http.HttpSession; import org.springframework.stereotype.Controller;import org.springframework.web.bind.annotation.RequestMapping; import com.test.socket.WebSocketTest; @Controller@RequestMapping(\"chatWebsocket\")public class ChartWebsocketController {@RequestMapping(\"login\")public void login(String username,HttpServletRequest request,HttpServletResponse response) throws Exception{HttpSession session=request.getSession();session.setAttribute(\"username\", username);WebSocketTest.setHttpSession(session);request.getRequestDispatcher(\"/socketChart.jsp\").forward(request, response);}@RequestMapping(\"loginOut\")public void loginOut(HttpServletRequest request,HttpServletResponse response) throws Exception{HttpSession session=request.getSession();session.removeAttribute(\"username\");request.getRequestDispatcher(\"/socketChart.jsp\").forward(request, response);}}
5、socket消息处理类，负责消息的接收与转发，作用类似于TCP的服务端，@ServerEndpoint(\"/websocketTest\")的作用是声明websocket的连接路径。
package com.test.socket; import java.io.IOException;import java.util.HashMap;import java.util.Map;import java.util.Map.Entry; import javax.servlet.http.HttpSession;import javax.websocket.OnClose;import javax.websocket.OnError;import javax.websocket.OnMessage;import javax.websocket.OnOpen;import javax.websocket.Session;import javax.websocket.server.ServerEndpoint;import com.google.gson.Gson; / @ServerEndpoint /@ServerEndpoint(\"/websocketTest\")public class WebSocketTest {private static int onlineCount = 0;//存放所有登录用户的Map集合，键：每个用户的唯一标识（用户名）private static Map<String,WebSocketTest> webSocketMap = new HashMap<String,WebSocketTest>();//session作为用户简历连接的唯一会话，可以用来区别每个用户private Session session;//httpsession用以在建立连接的时候获取登录用户的唯一标识（登录名）,获取到之后以键值对的方式存在Map对象里面private static HttpSession httpSession;public static void setHttpSession(HttpSession httpSession){WebSocketTest.httpSession=httpSession;}/ 连接建立成功调用的方法 @param session 可选的参数。session为与某个客户端的连接会话，需要通过它来给客户端发送数据 /@OnOpenpublic void onOpen(Session session) {Gson gson=new Gson();this.session = session;webSocketMap.put((String) httpSession.getAttribute(\"username\"), this);addOnlineCount(); // MessageDto md=new MessageDto();md.setMessageType(\"onlineCount\");md.setData(onlineCount+\"\");sendOnlineCount(gson.toJson(md));System.out.println(getOnlineCount());}/ 向所有在线用户发送在线人数 @param message /public void sendOnlineCount(String message){for (Entry<String,WebSocketTest> entry : webSocketMap.entrySet()) {try {entry.getValue().sendMessage(message);} catch (IOException e) {continue;}}}/ 连接关闭调用的方法 /@OnClosepublic void onClose() {for (Entry<String,WebSocketTest> entry : webSocketMap.entrySet()) {if(entry.getValue().session==this.session){webSocketMap.remove(entry.getKey());break;}}//webSocketMap.remove(httpSession.getAttribute(\"username\"));subOnlineCount(); // System.out.println(getOnlineCount());} / 服务器接收到客户端消息时调用的方法，（通过“@”截取接收用户的用户名） @param message 客户端发送过来的消息 @param session 数据源客户端的session /@OnMessagepublic void onMessage(String message, Session session) {Gson gson=new Gson();System.out.println(\"收到客户端的消息:\" + message);StringBuffer messageStr=new StringBuffer(message);if(messageStr.indexOf(\"@\")!=-1){String targetname=messageStr.substring(0, messageStr.indexOf(\"@\"));String sourcename=\"\";for (Entry<String,WebSocketTest> entry : webSocketMap.entrySet()) {//根据接收用户名遍历出接收对象if(targetname.equals(entry.getKey())){try {for (Entry<String,WebSocketTest> entry1 : webSocketMap.entrySet()) {//session在这里作为客户端向服务器发送信息的会话，用来遍历出信息来源if(entry1.getValue().session==session){sourcename=entry1.getKey();}}MessageDto md=new MessageDto();md.setMessageType(\"message\");md.setData(sourcename+\":\"+message.substring(messageStr.indexOf(\"@\")+1));entry.getValue().sendMessage(gson.toJson(md));} catch (IOException e) {e.printStackTrace();continue;}}}}} / 发生错误时调用 @param session @param error /@OnErrorpublic void onError(Session session, Throwable error) {error.printStackTrace();} / 这个方法与上面几个方法不一样。没有用注解，是根据自己需要添加的方法。 @param message @throws IOException /public void sendMessage(String message) throws IOException {this.session.getBasicRemote().sendText(message);// this.session.getAsyncRemote().sendText(message);} public static synchronized int getOnlineCount() {return onlineCount;} public static synchronized void addOnlineCount() {WebSocketTest.onlineCount++;} public static synchronized void subOnlineCount() {WebSocketTest.onlineCount--;}}
6、消息封装的数据传输对象
package com.chart.dto; public class MessageDto {private String messageType;private String data;public String getMessageType() {return messageType;}public void setMessageType(String messageType) {this.messageType = messageType;}public String getData() {return data;}public void setData(String data) {this.data = data;}}
