java WebSocket 简易聊天消息推送

àì夳堔傛蜴生んèń 2022-08-14 01:37 300阅读 0赞

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：

![Center][]

Guest1：

![Center 1][]

Guest2：

![Center 2][]

[Center]: /images/20220810/ed6edce2800b4c7f93de8433e3a4a42d.png
[Center 1]: /images/20220810/48c3aa6cf64b48ff9b55ca0ba7e6a541.png
[Center 2]: /images/20220810/d3eff66fb37740ab931ba627a769c2bb.png