java WebSocket实现聊天消息推送功能

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<String,Object> connections = new HashMap<String,Object>();
 
  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); 
 } 
  }
}

/**
 * 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());
  }
}

<%@ 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>