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<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：