websocket应用

╰+哭是因爲堅強的太久メ 2021-11-27 03:12 283阅读 0赞

pom

<dependency>
                <groupId>javax.websocket</groupId>
                <artifactId>javax.websocket-api</artifactId>
                <version>1.0</version>
                <scope>provided</scope>
            </dependency>

代码

package cn.alibaba.utils;
    
    import javax.websocket.*;
    import javax.websocket.server.PathParam;
    import javax.websocket.server.ServerEndpoint;
    import java.io.IOException;
    import java.util.HashMap;
    import java.util.Map;
    import java.util.concurrent.ConcurrentHashMap;
    
    
    @ServerEndpoint("/websocket/{username}")
    public class WebSocketServer {
    
        //记录当前连接数
        private static int onlineCount = 0;
    
        //
        private static Map<String,WebSocketServer> webSockets = new ConcurrentHashMap<String, WebSocketServer>();
    
        private Session session;
    
        /**
         * 建立连接
         * @param session
         */
        @OnOpen
        public void onOpen(@PathParam(value = "username") String username, Session session){
            this.session = session;
            webSockets.put(username,this);
            onlineCount ++ ;
            System.out.println("现在在线人数为："+onlineCount);
        }
    
        /**
         * 连接关闭
         */
        @OnClose
        public void onClose(@PathParam(value = "username") String username){
            webSockets.remove(username);
            onlineCount -- ;
            System.out.println("现在在线人数为："+onlineCount);
        }
    
        @OnMessage
        public void onMessage(@PathParam(value = "username") String username,String message,Session session){
            System.out.println("收到消息："+message);
            if (webSockets.containsKey(username)){
                try {
                    webSockets.get(username).session.getBasicRemote().sendText(username);
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
    
        }
    
        @OnError
        public void onError(Session session,Throwable error){
            System.out.println("发生错误");
            error.printStackTrace();
        }
    }

页面调用

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
    <html>
    <head>
        <title>主页</title>
    
        <style>
    
        </style>
    </head>
    <body>
    Welcome<br/><input id="text" type="text"/>
    <button  onclick="send()">发送消息</button>
    <hr/>
    <button onclick="closeWebSocket()">关闭WebSocket连接</button>
    <hr/>
    <div id="message"></div>
    
    </body>
    
    <link href="http://libs.baidu.com/bootstrap/3.0.3/css/bootstrap.min.css" rel="stylesheet">
    
    
    <script src="https://apps.bdimg.com/libs/jquery/2.1.4/jquery.min.js"></script>
    <script>
    
        var websocket = null;
        //判断当前浏览器是否支持WebSocket
            if ('WebSocket' in window) {
                var username = "1234";//根据你得要求获取username
                websocket = new WebSocket("ws://127.0.0.1:8080/websocket/"+username);
            } else {
                alert('当前浏览器 Not support websocket')
            }
    
            //连接发生错误的回调方法
            websocket.onerror = function () {
                setMessageInnerHTML("WebSocket连接发生错误");
            };
    
            //连接成功建立的回调方法
            websocket.onopen = function () {
                setMessageInnerHTML("WebSocket连接成功");
            }
    
            //接收到消息的回调方法
            websocket.onmessage = function (event) {
                setMessageInnerHTML(event.data);
            }
    
            //连接关闭的回调方法
            websocket.onclose = function () {
                setMessageInnerHTML("WebSocket连接关闭");
            }
    
            //监听窗口关闭事件，当窗口关闭时，主动去关闭websocket连接，防止连接还没断开就关闭窗口，server端会抛异常。
            window.onbeforeunload = function () {
                closeWebSocket();
            }
    
    
        //将消息显示在网页上
        function setMessageInnerHTML(innerHTML) {
            document.getElementById('message').innerHTML += innerHTML + '<br/>';
        }
    
        //关闭WebSocket连接
        function closeWebSocket() {
            websocket.close();
        }
    
        //发送消息
        function send() {
            var message = document.getElementById('text').value;
            websocket.send(message);
        }
    
    </script>
    </html>