SpringBoot集成WebSocket实现客户端与服务端通信

话不多说，直接上代码看效果！

一、服务端：

1、引用依赖

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

2、添加配置文件 WebSocketConfig

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

3、编写WebSocket服务端接收、发送功能

? 声明接口代码：

public interface IWebSocketService {

    void sendMessage(String message, List<String> toSids);

    String getMessage(String msg);
}

? 实现类代码：

@Slf4j
@Service
@ServerEndpoint("/api/websocket/{sid}")
public class IWebSocketServiceImpl implements IWebSocketService {
    @Autowired
    RabbitTemplate rabbitTemplate;

    //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 AtomicInteger onlineCount = new AtomicInteger(0);
    //concurrent包的线程安全Set，用来存放每个客户端对应的WebSocket对象。
    private static CopyOnWriteArraySet<IWebSocketServiceImpl> webSocketSet = new CopyOnWriteArraySet<>();

    //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sid
    private String sid = "";

    @Override
    public void sendMessage(String message, List<String> toSids) {
        log.info("推送消息到客户端 " + toSids + "，推送内容:" + message);

        for (IWebSocketServiceImpl item : webSocketSet) {
            try {
                if (CollectionUtils.isEmpty(toSids)) {
                    item.sendMessage(message);
                } else if (toSids.contains(item.sid)) {
                    item.sendMessage(message);
                }
            } catch (IOException e) {
                continue;
            }
        }
    }

    @Override
    public String getMessage(String msg) {
        return null;
    }


    /**
     * 连接建立成功调用的方法
     */
    @OnOpen
    public void onOpen(Session session, @PathParam("sid") String sid) {
        this.session = session;
        webSocketSet.add(this);     // 加入set中
        this.sid = sid;
        addOnlineCount();           // 在线数加1
        try {
//            sendMessage("conn_success");
            log.info("有新客户端开始监听,sid=" + sid + ",当前在线人数为:" + getOnlineCount());
        } catch (Exception e) {
            log.error("websocket IO Exception");
        }
    }

    /**
     * 连接关闭调用的方法
     */
    @OnClose
    public void onClose() {
        webSocketSet.remove(this);  // 从set中删除
        subOnlineCount();              // 在线数减1
        // 断开连接情况下，更新主板占用情况为释放
        log.info("释放的sid=" + sid + "的客户端");
        releaseResource();
    }

    @OnMessage
    public void onMessage(String message, Session session) {
        log.info("收到来自客户端 sid=" + sid + " 的信息:" + message);
        //此处为MQ接收功能，如果不使用则可以屏蔽,如果有需要可使用
//        if (rabbitTemplate == null) {
//            ApplicationContext context = springUtils.getApplicationContext();
//            rabbitTemplate = context.getBean(RabbitTemplate.class);
//        }
//        rabbitTemplate.convertAndSend(RabbitmqConfig.EXCHANGE_TOPICS_INFORM, //RabbitmqConfig.ROUTINGKEY_RETURN, message);
//        rabbitTemplate.convertAndSend(RabbitmqConfig.EXCHANGE_TOPICS_INFORM, //RabbitmqConfig.ROUTINGKEY_RETURN, message);
        // 群发消息
//        List<String> sids = new ArrayList<>();
//        for (WebSocketServer item : webSocketSet) {
//            sids.add(item.sid);
//        }
//        try {
//            sendMessage("客户端 " + this.sid + "发布消息：" + message, sids);
//        } catch (IOException e) {
//            e.printStackTrace();
//        }
    }

    private void releaseResource() {
        // 这里写释放资源和要处理的业务
        log.info("有一连接关闭！当前在线人数为" + getOnlineCount());
    }

    /**
     * 发生错误回调
     */
    @OnError
    public void onError(Session session, Throwable error) {
        log.error(session.getAsyncRemote() + "客户端发生错误");
        error.printStackTrace();
    }

    /**
     * 实现服务器主动推送消息到 指定客户端
     */
    public void sendMessage(String message) throws IOException {
        this.session.getAsyncRemote().sendText(message);
    }

    /**
     * 获取当前在线人数
     *
     * @return
     */
    public int getOnlineCount() {
        return onlineCount.get();
    }

    /**
     * 当前在线人数 +1
     *
     * @return
     */
    public void addOnlineCount() {
        onlineCount.getAndIncrement();
    }

    /**
     * 当前在线人数 -1
     *
     * @return
     */
    public void subOnlineCount() {
        onlineCount.getAndDecrement();
    }

    /**
     * 获取当前在线客户端对应的WebSocket对象
     *
     * @return
     */
    public CopyOnWriteArraySet<IWebSocketServiceImpl> getWebSocketSet() {
        return webSocketSet;
    }

}

4、如果不需要实现客户端功能，此处可选择前端调用，奉上代码

<!DOCTYPE html>
<html>

<head>
    <meta charset="utf-8">
    <title>Java后端WebSocket的Tomcat实现</title>
    <script src="https://cdn.bootcdn.net/ajax/libs/jquery/3.6.0/jquery.min.js"></script>
</head>

<body>
    <div id="message"></div>
    <hr />
    <div id="main"></div>
    <div id="client"></div>
    <input id="text" type="text" />
    <button onclick="send()">发送消息</button>
    <hr />
    <button onclick="closeWebSocket()">关闭WebSocket连接</button>
</body>
<script type="text/javascript">

    var cid = Math.floor(Math.random() * 100); // 随机生成客户端id
    document.getElementById('client').innerHTML += "客户端 id = " + cid + '<br/>';

    var websocket = null;

    //判断当前浏览器是否支持WebSocket
    if ('WebSocket' in window) {
        // 改成你的地址
        websocket = new WebSocket("ws://127.0.0.1:9204/api/websocket/" + cid);
    } 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.onerror: WebSocket连接发生错误");
    };

    //连接成功建立的回调方法
    websocket.onopen = function () {
        setMessageInnerHTML("websocket.onopen: WebSocket连接成功");
    }

    //接收到消息的回调方法
    websocket.onmessage = function (event) {
        setMessageInnerHTML("websocket.onmessage: " + event.data);
    }

    //连接关闭的回调方法
    websocket.onclose = function () {
        setMessageInnerHTML("websocket.onclose: 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();
        alert('websocket.close: 关闭websocket连接')
    }

    //发送消息
    function send() {
        var message = document.getElementById('text').value;
        try {
            websocket.send('{"msg":"' + message + '"}');
            setMessageInnerHTML("websocket.send: " + message);
        } catch (err) {
            console.error("websocket.send: " + message + " 失败");
        }
    }
</script>

</html>

二、客户端：

1、引用依赖

<dependency>
    <groupId>org.java-websocket</groupId>
    <artifactId>Java-WebSocket</artifactId>
    <version>1.3.8</version>
</dependency>

2、自定义WebSocket客户端，继承WebSocketClient类，实现发送、接收等功能

/**
 * 自定义WebSocket客户端
 */
public class CustomizedWebSocketClient extends WebSocketClient {
    private static final Logger logger = LoggerFactory.getLogger(CustomizedWebSocketClient.class);

    //用来接收数据
    private String excptMessage;

    /**
     * 线程安全的Boolean -是否受到消息
     */
    public AtomicBoolean hasMessage = new AtomicBoolean(false);

    /**
     * 线程安全的Boolean -是否已经连接
     */
    private AtomicBoolean hasConnection = new AtomicBoolean(false);

    /**
     * 构造方法
     *
     * @param serverUri
     */
    public CustomizedWebSocketClient(URI serverUri) {
        super(serverUri);
        logger.info("CustomizeWebSocketClient init:" + serverUri.toString());
    }

    /**
     * 打开连接是方法
     *
     * @param serverHandshake
     */
    @Override
    public void onOpen(ServerHandshake serverHandshake) {
        logger.info("CustomizeWebSocketClient onOpen");
    }

    /**
     * 收到消息时
     *
     * @param s
     */
    @Override
    public void onMessage(String s) {
        hasMessage.set(true);
        logger.info("CustomizeWebSocketClient onMessage:" + s);
    }

    public void sendMessage(String message){
        this.send(message);
        logger.info("已发送消息：" + message);
    }

    /**
     * 当连接关闭时
     *
     * @param i
     * @param s
     * @param b
     */
    @Override
    public void onClose(int i, String s, boolean b) {
        this.hasConnection.set(false);
        this.hasMessage.set(false);
        logger.info("CustomizeWebSocketClient onClose:" + s);
    }

    /**
     * 发生error时
     *
     * @param e
     */
    @Override
    public void onError(Exception e) {
        logger.error("CustomizeWebSocketClient onError:" + e);
    }

    @Override
    public void connect() {
        if(!this.hasConnection.get()){
            super.connect();
            hasConnection.set(true);
        }
    }

    //获取接收到的信息
    public String getExcptMessage() {
        if(excptMessage != null){
            String message = new String(excptMessage);
            excptMessage = null;
            return message;
        }
        return null;
    }
}

3、创建连接封装类，uri对应socket服务的ip和端口号

public class WebSocketClientSingleton {
    private static CustomizedWebSocketClient client;
    private WebSocketClientSingleton(){}

    public static CustomizedWebSocketClient getInstance() {
        if (client == null || client.isClosed()) {
            String webSocketUri = "ws://localhost:9204/api/websocket/12345678";
            try {
                //实例WebSocketClient对象，并连接到WebSocket服务端
                client = new CustomizedWebSocketClient(new URI(webSocketUri));
                client.connect();
                //等待服务端响应
                while (!client.getReadyState().equals(WebSocket.READYSTATE.OPEN)) {
                    System.out.println("连接中···请稍后");
                    Thread.sleep(1000);
                }
            } catch (URISyntaxException e) {
                e.printStackTrace();
            } catch (InterruptedException e) {
                throw new RuntimeException(e);
            }
//            return client;
        }
        return client;
    }

    public static void closeClient(CustomizedWebSocketClient client){
        client.close();
    }
}

三、测试

@Autowired
    private IWebSocketService webSocketService;

调用代码：

//懒汉模式创建客户端连接
CustomizedWebSocketClient customizedWebSocketClient = WebSocketClientSingleton.getInstance();
//客户端发送消息
customizedWebSocketClient.sendMessage("----客户端发送消息啦-----1123");
//服务端发送消息
webSocketService.sendMessage("服务端发送消息啦----223333",null);
//关闭连接
WebSocketClientSingleton.closeClient(customizedWebSocketClient);

控制台打印效果：

总结完毕