java WebSocket 简易聊天消息推送

环境：

JDK.1.7.0_51

apache-tomcat-7.0.53

Java jar包：tomcat-coyote.jar、tomcat-juli.jar、websocket-api.jar

ChatAnnotation消息发送类：

 import java.io.IOException;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.concurrent.atomic.AtomicInteger;

 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 org.apache.juli.logging.Log;
 import org.apache.juli.logging.LogFactory;

 import com.util.HTMLFilter;

 /**
  * WebSocket 消息推送服务类
  * @author 胡汉三
  *
  * 2014-11-18 下午7:53:13
  */
 @ServerEndpoint(value = "/websocket/chat")
 public class ChatAnnotation {

     private static final Log log = LogFactory.getLog(ChatAnnotation.class);

     private static final String GUEST_PREFIX = "Guest";
     private static final AtomicInteger connectionIds = new AtomicInteger(0);
     private static final Map connections = new HashMap();

     private final String nickname;
     private Session session;

     public ChatAnnotation() {
         nickname = GUEST_PREFIX + connectionIds.getAndIncrement();
     }


     @OnOpen
     public void start(Session session) {
         this.session = session;
         connections.put(nickname, this);
         String message = String.format("* %s %s", nickname, "has joined.");
         broadcast(message);
     }


     @OnClose
     public void end() {
         connections.remove(this);
         String message = String.format("* %s %s",
                 nickname, "has disconnected.");
         broadcast(message);
     }


     /**
      * 消息发送触发方法
      * @param message
      */
     @OnMessage
     public void incoming(String message) {
         // Never trust the client
         String filteredMessage = String.format("%s: %s",
                 nickname, HTMLFilter.filter(message.toString()));
         broadcast(filteredMessage);
     }

     @OnError
     public void onError(Throwable t) throws Throwable {
         log.error("Chat Error: " + t.toString(), t);
     }

     /**
      * 消息发送方法
      * @param msg
      */
     private static void broadcast(String msg) {
         if(msg.indexOf("Guest0")!=-1){
             sendUser(msg);
         } else{
             sendAll(msg);
         }
     }

     /**
      * 向所有用户发送
      * @param msg
      */
     public static void sendAll(String msg){
         for (String key : connections.keySet()) {
             ChatAnnotation client = null ;
             try {
                 client = (ChatAnnotation) connections.get(key);
                 synchronized (client) {
                     client.session.getBasicRemote().sendText(msg);
                 }
             } catch (IOException e) {
                 log.debug("Chat Error: Failed to send message to client", e);
                 connections.remove(client);
                 try {
                     client.session.close();
                 } catch (IOException e1) {
                     // Ignore
                 }
                 String message = String.format("* %s %s",
                         client.nickname, "has been disconnected.");
                 broadcast(message);
             }
         }
     }

     /**
      * 向指定用户发送消息
      * @param msg
      */
     public static void sendUser(String msg){
         ChatAnnotation c = (ChatAnnotation)connections.get("Guest0");
         try {
             c.session.getBasicRemote().sendText(msg);
         } catch (IOException e) {
             log.debug("Chat Error: Failed to send message to client", e);
             connections.remove(c);
             try {
                 c.session.close();
             } catch (IOException e1) {
                 // Ignore
             }
             String message = String.format("* %s %s",
                     c.nickname, "has been disconnected.");
             broadcast(message);
         }
     }
 }

HTMLFilter工具类：

 /**
  * HTML 工具类
  *
  * @author 胡汉三
  */
 public final class HTMLFilter {
     public static String filter(String message) {
         if (message == null)
             return (null);
         char content[] = new char[message.length()];
         message.getChars(0, message.length(), content, 0);
         StringBuilder result = new StringBuilder(content.length + 50);
         for (int i = 0; i < content.length; i++) {
             switch (content[i]) {
             case '<':
                 result.append("<");
                 break;
             case '>':
                 result.append(">");
                 break;
             case '&':
                 result.append("&");
                 break;
             case '"':
                 result.append(""");
                 break;
             default:
                 result.append(content[i]);
             }
         }
         return (result.toString());
     }
 }

页面：

 <%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
 <%
 String path = request.getContextPath();
 String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
 %>

 xml version="1.0" encoding="UTF-8"?>
 <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
 <head>
     <title>测试title>
     <style type="text/css">
         input#chat {
             width: 410px
         }

         #console-container {
             width: 400px;
         }

         #console {
             border: 1px solid #CCCCCC;
             border-right-color: #999999;
             border-bottom-color: #999999;
             height: 170px;
             overflow-y: scroll;
             padding: 5px;
             width: 100%;
         }

         #console p {
             padding: 0;
             margin: 0;
         }
  style>
     <script type="text/javascript">

         var Chat = {};

         Chat.socket = null;

         Chat.connect = (function(host) {
             if ('WebSocket' in window) {
                 Chat.socket = new WebSocket(host);
             } else if ('MozWebSocket' in window) {
                 Chat.socket = new MozWebSocket(host);
             } else {
                 Console.log('Error: WebSocket is not supported by this browser.');
                 return;
             }

             Chat.socket.onopen = function () {
                 Console.log('Info: WebSocket connection opened.');
                 document.getElementById('chat').onkeydown = function(event) {
                     if (event.keyCode == 13) {
                         Chat.sendMessage();
                     }
                 };
             };

             Chat.socket.onclose = function () {
                 document.getElementById('chat').onkeydown = null;
                 Console.log('Info: WebSocket closed.');
             };

             Chat.socket.onmessage = function (message) {
                 Console.log(message.data);
             };
         });

         Chat.initialize = function() {
             if (window.location.protocol == 'http:') {
                 Chat.connect('ws://' + window.location.host + '/socket2/websocket/chat');
             } else {
                 Chat.connect('wss://' + window.location.host + '/socket2/websocket/chat');
             }
         };

         Chat.sendMessage = (function() {
             var message = document.getElementById('chat').value;
             if (message != '') {
                 Chat.socket.send(message);
                 document.getElementById('chat').value = '';
             }
         });

         var Console = {};

         Console.log = (function(message) {
             var console = document.getElementById('console');
             var p = document.createElement('p');
             p.style.wordWrap = 'break-word';
             p.innerHTML = message;
             console.appendChild(p);
             while (console.childNodes.length > 25) {
                 console.removeChild(console.firstChild);
             }
             console.scrollTop = console.scrollHeight;
         });

         Chat.initialize();


         document.addEventListener("DOMContentLoaded", function() {
             // Remove elements with "noscript" class - <noscript> is not allowed in XHTML
             var noscripts = document.getElementsByClassName("noscript");
             for (var i = 0; i < noscripts.length; i++) {
                 noscripts[i].parentNode.removeChild(noscripts[i]);
             }
         }, false);

    script>
 head>
 <body>
 <div class="noscript"><h2 style="color: #ff0000">Seems your browser doesn't support Javascript! Websockets rely on Javascript being enabled. Please enable
     Javascript and reload this page!h2>div>
 <div>
     <p>
         <input type="text" placeholder="请输入内容" id="chat" />
     p>
     <div id="console-container">
         <div id="console"/>
     div>
 div>
 body>
 html>

可指定发送给某个用户，也可全部发送，详情见ChatAnnotation类的broadcast方法。

程序发布时记得删除tomcat-coyote.jar、tomcat-juli.jar、websocket-api.jar这三个jar包在启动Tomcat。

程序截图，Guest0用户发送信息的信息，在后台进行了判断只发送给自己：

Guest1：

Guest2：