java WebSocket实现聊天消息推送功能

本文实例为大家分享了java WebSocket实现聊天消息推送功能的具体代码，供大家参考，具体内容如下

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<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);
}
 }
}

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：

来源：https://blog.csdn.net/hzw2312/article/details/41252159/