SpringBoot整合WebSocket实现实时通信功能

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

@Component
@ServerEndpoint("/server/{uid}")
@Slf4j
public class WebSocketServer {

    /**
     * 记录当前在线连接数
     */
    private static int onlineCount = 0;

    /**
     * 使用线程安全的ConcurrentHashMap来存放每个客户端对应的WebSocket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;

    /**
     * 接收客户端消息的uid
     */
    private String uid = "";

    /**
     * 连接建立成功调用的方法
     * @param session
     * @param uid
     */
    @OnOpen
    public void onOpen(Session session, @PathParam("uid") String uid) {
        this.session = session;
        this.uid = uid;
        if (webSocketMap.containsKey(uid)) {
            webSocketMap.remove(uid);
            //加入到set中
            webSocketMap.put(uid, this);
        } else {
            //加入set中
            webSocketMap.put(uid, this);
            //在线数加1
            addOnlineCount();
        }

        log.info("用户【" + uid + "】连接成功，当前在线人数为:" + getOnlineCount());
        try {
            sendMsg("连接成功");
        } catch (IOException e) {
            log.error("用户【" + uid + "】网络异常!", e);
        }
    }

    /**
     * 连接关闭调用的方法
     */
    @OnClose
    public void onClose() {
        if (webSocketMap.containsKey(uid)) {
            webSocketMap.remove(uid);
            //从set中删除
            subOnlineCount();
        }
        log.info("用户【" + uid + "】退出，当前在线人数为:" + getOnlineCount());
    }

    /**
     * 收到客户端消息后调用的方法
     * @param message 客户端发送过来的消息
     * @param session 会话
     */
    @OnMessage
    public void onMessage(String message, Session session) {
        log.info("用户【" + uid + "】发送报文:" + message);
        //群发消息
        //消息保存到数据库或者redis
        if (StringUtils.isNotBlank(message)) {
            try {
                //解析发送的报文
                ObjectMapper objectMapper = new ObjectMapper();
                Map<String, String> map = objectMapper.readValue(message, new TypeReference<Map<String, String>>(){});
                //追加发送人(防止串改)
                map.put("fromUID", this.uid);
                String toUID = map.get("toUID");
                //传送给对应的toUserId用户的WebSocket
                if (StringUtils.isNotBlank(toUID) && webSocketMap.containsKey(toUID)) {
                    webSocketMap.get(toUID).sendMsg(objectMapper.writeValueAsString(map));
                } else {
                    //若果不在这个服务器上，可以考虑发送到mysql或者redis
                    log.error("请求目标用户【" + toUID + "】不在该服务器上");
                }
            } catch (Exception e) {
                log.error("用户【" + uid + "】发送消息异常！", e);
            }
        }
    }

    /**
     * 处理错误
     * @param session
     * @param error
     */
    @OnError
    public void onError(Session session, Throwable error) {
        log.error("用户【" + this.uid + "】处理消息错误，原因:" + error.getMessage());
        error.printStackTrace();
    }

    /**
     * 实现服务器主动推送
     * @param msg
     * @throws IOException
     */
    private void sendMsg(String msg) throws IOException {
        this.session.getBasicRemote().sendText(msg);
    }

    /**
     * 发送自定义消息
     * @param message
     * @param uid
     * @throws IOException
     */
    public static void sendInfo(String message, @PathParam("uid") String uid) throws IOException {
        log.info("发送消息到用户【" + uid + "】发送的报文:" + message);
        if (!StringUtils.isEmpty(uid) && webSocketMap.containsKey(uid)) {
            webSocketMap.get(uid).sendMsg(message);
        } else {
            log.error("用户【" + uid + "】不在线！");
        }
    }

    private static synchronized int getOnlineCount() {
        return onlineCount;
    }

    private static synchronized void addOnlineCount() {
        WebSocketServer.onlineCount++;
    }

    private static synchronized void subOnlineCount() {
        WebSocketServer.onlineCount--;
    }

}

@RestController
public class WebSocketController {

    @GetMapping("/page")
    public ModelAndView page() {
        return new ModelAndView("webSocket");
    }

    @RequestMapping("/push/{toUID}")
    public ResponseEntity<String> pushToClient(String message, @PathVariable String toUID) throws Exception {
        WebSocketServer.sendInfo(message, toUID);
        return ResponseEntity.ok("Send Success!");
    }
}

<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8">
    <title>WebSocket消息通知</title>
</head>
<script src="https://cdn.bootcss.com/jquery/3.3.1/jquery.js"></script>
<script>
    var socket;

    //打开WebSocket
    function openSocket() {
        if (typeof (WebSocket) === "undefined") {
            console.log("您的浏览器不支持WebSocket");
        } else {
            console.log("您的浏览器支持WebSocket");
            //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 = "http://localhost:8080/socket/server/" + $("#uid").val();
            //将https与http协议替换为ws协议
            socketUrl = socketUrl.replace("https", "ws").replace("http", "ws");
            console.log(socketUrl);
            if (socket != null) {
                socket.close();
                socket = null;
            }
            socket = new WebSocket(socketUrl);
            //打开事件
            socket.onopen = function () {
                console.log("WebSocket已打开");
                //socket.send("这是来自客户端的消息" + location.href + new Date());
            };
            //获得消息事件
            socket.onmessage = function (msg) {
                console.log(msg.data);
                //发现消息进入,开始处理前端触发逻辑
            };
            //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");
            }
        }
    }

    //发送消息
    function sendMessage() {
        if (typeof (WebSocket) === "undefined") {
            console.log("您的浏览器不支持WebSocket");
        } else {
            console.log("您的浏览器支持WebSocket");
            console.log('{"toUID":"' + $("#toUID").val() + '","Msg":"' + $("#msg").val() + '"}');
            socket.send('{"toUID":"' + $("#toUID").val() + '","Msg":"' + $("#msg").val() + '"}');
        }
    }
</script>
<body>
<p>【uid】：
<div><input id="uid" name="uid" type="text" value="1"></div>
<p>【toUID】：
<div><input id="toUID" name="toUID" type="text" value="2"></div>
<p>【Msg】：
<div><input id="msg" name="msg" type="text" value="hello WebSocket2"></div>
<p>【第一步操作:】：
<div>
    <button onclick="openSocket()">开启socket</button>
</div>
<p>【第二步操作:】：
<div>
    <button onclick="sendMessage()">发送消息</button>
</div>
</body>

</html>