SpringBoot+WebSocket在线聊天

先看一下页面效果，有点简单粗暴！哈哈哈哈哈，别介意.
本文参考：SpringBoot2.0集成WebSocket，实现后台向前端推送信息

新建一个springboot项目

引入相关依赖

  <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <!-- https://mvnrepository.com/artifact/org.apache.commons/commons-lang3 -->
        <dependency>
            <groupId>org.apache.commons</groupId>
            <artifactId>commons-lang3</artifactId>
            <version>3.0</version>
        </dependency>

        <!--com.alibaba/fastjson-->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>fastjson</artifactId>
            <version>1.2.62</version>
        </dependency>

        <!--websocket依赖-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-websocket</artifactId>
        </dependency>

        <!--thymeleaf-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-thymeleaf</artifactId>
        </dependency>

Java代码

WebSocketConfig

@Configuration
public class WebSocketConfig {
    @Bean
    public ServerEndpointExporter serverEndpointExporter(){
        return new ServerEndpointExporter();
    }
}

PageController

@RestController
public class PageController {
    @GetMapping("chat")
    public ModelAndView tochat(){
        return new ModelAndView("/chat");
    }
}

WebSocketServer

@ServerEndpoint("/chat/{userName}")
@Component
@Slf4j
public class WebSocketServer {

    /**静态变量，用来记录当前在线连接数。应该把它设计成线程安全的。*/
    private static int onlineCount = 0;
    /**concurrent包的线程安全Set，用来存放每个客户端对应的MyWebSocket对象。*/
    private static ConcurrentHashMap<String,WebSocketServer> webSocketMap = new ConcurrentHashMap<>();
    /**与某个客户端的连接会话，需要通过它来给客户端发送数据*/
    private Session session;

    /**接收userId*/
    private String userName="";

    /**
     * @Description: 连接建立成功调用的方法
     * @params: [session, userId]
     * @return: void
     * @Author: wangxianlin
     * @Date: 2020/5/9 9:13 PM
     */
    @Onopen
    public void onopen(Session session,@PathParam("userName") String userName) {
        this.session = session;
        this.userName=userName;
        if(webSocketMap.containsKey(userName)){
            webSocketMap.remove(userName);
            webSocketMap.put(userName,this);
            //加入set中
        }else{
            webSocketMap.put(userName,this);
            //加入set中
            addOnlineCount();
            //在线数加1
        }

        log.info("用户连接:"+userName+",当前在线人数为:" + getonlineCount());

        try {
            sendMessage("{\"msg\":\"连接成功\"}");
        } catch (IOException e) {
            log.error("用户:"+userName+",网络异常!!!!!!");
        }
    }

    /**
     * @Description: 连接关闭调用的方法
     * @params: []
     * @return: void
     * @Author: wangxianlin
     * @Date: 2020/5/9 9:13 PM
     */
    @OnClose
    public void onClose() {
        if(webSocketMap.containsKey(userName)){
            webSocketMap.remove(userName);
            //从set中删除
            subOnlineCount();
        }
        log.info("用户退出:"+userName+",当前在线人数为:" + getonlineCount());
    }


    /**
     * @Description: 收到客户端消息后调用的方法
     * @params: [message, session]
     * @return: void
     * @Author: wangxianlin
     * @Date: 2020/5/9 9:13 PM
     */
    @OnMessage
    public void onMessage(String message, Session session) {
        log.info("用户消息:"+userName+",报文:"+message);
        //可以群发消息
        //消息保存到数据库、redis
        if(StringUtils.isNotBlank(message)){
            try {
                //解析发送的报文
                JSONObject jsonObject = JSON.parSEObject(message);
                //追加发送人(防止串改)
                jsonObject.put("sender",this.userName);
                String receiver=jsonObject.getString("receiver");
                //传送给对应toUserId用户的websocket
                if(StringUtils.isNotBlank(receiver)&&webSocketMap.containsKey(receiver)){
                    webSocketMap.get(receiver).sendMessage(jsonObject.toJSONString());
                }else{
                    log.error("请求的receiver:"+receiver+"不在该服务器上");
                    //否则不在这个服务器上，发送到MysqL或者redis
                }
            }catch (Exception e){
                e.printstacktrace();
            }
        }
    }

    /**
     *
     * @param session
     * @param error
     */
    @OnError
    public void one rror(Session session, Throwable error) {
        log.error("用户错误:"+this.userName+",原因:"+error.getMessage());
        error.printstacktrace();
    }

    /**
     * 实现服务器主动推送
     */
    public void sendMessage(String message) throws IOException {
        this.session.getBasicRemote().sendText(message);
    }

    /**
     * @Description: 发送消息
     * @params: [message, userId]
     * @return: void
     * @Author: wangxianlin
     * @Date: 2020/5/9 9:09 PM
     */
    public static void sendInfo(String message,@PathParam("userId") String userId) throws IOException {
        log.info("发送消息到:"+userId+"，报文:"+message);
        if(StringUtils.isNotBlank(userId)&&webSocketMap.containsKey(userId)){
            webSocketMap.get(userId).sendMessage(message);
        }else{
            log.error("用户"+userId+",不在线！");
        }
    }

    /**
     * @Description: 获取在线人数
     * @params: []
     * @return: int
     * @Author: wangxianlin
     * @Date: 2020/5/9 9:09 PM
     */
    public static synchronized int getonlineCount() {
        return onlineCount;
    }

    /**
     * @Description: 在线人数+1
     * @params: []
     * @return: void
     * @Author: wangxianlin
     * @Date: 2020/5/9 9:09 PM
     */
    public static synchronized void addOnlineCount() {
        WebSocketServer.onlineCount++;
    }

    /**
     * @Description: 在线人数-1
     * @params: []
     * @return: void
     * @Author: wangxianlin
     * @Date: 2020/5/9 9:09 PM
     */
    public static synchronized void subOnlineCount() {
        WebSocketServer.onlineCount--;
    }
}

前端HTMl

<div class="layui-container">
    <div class="layui-row">
        <div class="layui-col-md12">
            <fieldset class="layui-elem-field layui-field-title" style="margin-top: 25px;">
                <legend style="margin-left: 40%;">简单粗暴的聊天界面</legend>
            </fieldset>
            <div class="grid-demo grid-demo-bg2" style="text-align: center">
                <form class="layui-form">
                    <div class="layui-form-item">
                        <label class="layui-form-label">接收者</label>
                        <div class="layui-input-block">
                            <input type="text" id="receiver" lay-verify="title" autocomplete="off" class="layui-input">
                        </div>
                    </div>
                    <div class="layui-form-item">
                        <label class="layui-form-label">发送者</label>
                        <div class="layui-input-block">
                            <input type="text" id="sender" autocomplete="off" class="layui-input">
                        </div>
                    </div>

                    <div class="layui-form-item layui-form-text">
                        <label class="layui-form-label">消息</label>
                        <div class="layui-input-block">
                            <textarea placeholder="请输入内容" class="layui-textarea" id="msg"></textarea>
                        </div>
                    </div>
                    <div class="layui-col-md12" style="margin-left: 4%">
                        <div class="layui-tab layui-tab-card" style="height: 200px;overflow: auto">
                            <fieldset class="layui-elem-field layui-field-title">
                                <legend>消息记录</legend>
                            </fieldset>
                            <div id="msgDiv">

                            </div>
                        </div>
                    </div>

                    <div class="layui-form-item">
                        <div class="layui-input-block">
                            <button type="button" class="layui-btn layui-btn-primary" onclick="establishConnection()">
                                建立连接
                            </button>
                            <button type="button" class="layui-btn layui-btn-primary" onclick="sendMessage()">发送消息
                            </button>
                        </div>
                    </div>
                </form>
            </div>
        </div>
    </div>
</div>
<script type="text/javascript" th:src="@{/javascript/jquery-2.1.4.js}"></script>
<!--layui-->
<script type="text/javascript" th:src="@{/plugins/layui/layui.js}"></script>

JavaScript代码

var socket;
    if (typeof(WebSocket) == "undefined") {
        console.log("您的浏览器不支持WebSocket");
    } else {

        /***建立连接*/
        function establishConnection() {
            var userName = $("#sender").val();
            if (userName == '' || userName == null) {
                alert("请输入发送者");
                return;
            }
            //实现化WebSocket对象，指定要连接的服务器地址与端口  建立连接
            var socketUrl = "" + window.location.protocol + "//" + window.location.host + "/chat/" + userName;
            socketUrl = socketUrl.replace("https", "ws").replace("http", "ws");
            if (socket != null) {
                socket.close();
                socket = null;
            }
            socket = new WebSocket(socketUrl);
            //打开事件
            socket.onopen = function () {
                console.log("开始建立链接....")
            };
            //关闭事件
            socket.onclose = function () {
                console.log("websocket已关闭");
            };
            //发生了错误事件
            socket.onerror = function () {
                console.log("websocket发生了错误");
            };
            /**
             * 接收消息
             * @param msg
             */
            socket.onmessage = function (msg) {
                msg = JSON.parse(msg.data);
                if (msg.msg != '连接成功') {
                    $("#msgDiv").append('<p class="user">用户名：' + msg.sender + '</p><p class="chat">' + msg.msg + '</p>');
                }
            };
        }

        /**
         * 发送消息
         */
        function sendMessage() {
            var msg = $("#msg").val();
            if (msg == '' || msg == null) {
                alert("消息内容不能为空");
                return;
            }
            var receiver = $("#receiver").val();
            if (receiver == '' || receiver == null) {
                alert("接收人不能为空");
                return;
            }
            var msgObj = {
                receiver: receiver,
                msg: msg
            };
            socket.send(JSON.stringify(msgObj));
        }
    }