WebSocket message notification implementation

1. Introduction to WebSocket

WebSocket is a protocol for full-duplex communication over a TCP connection, establishing a communication channel between the client and the server. The browser and server only need one handshake, and a persistent connection can be created directly between the two for bidirectional data transmission.

2. Implementation steps

1. SpringBoot integrates Websocket

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

2. WebSocket server

@Slf4j
@Component
@ServerEndpoint("/websocket/{userName}")
public class WebSocket {
    
    

    private Session session;

    private static CopyOnWriteArraySet<WebSocket> webSockets =new CopyOnWriteArraySet<>();
    private static Map<String,Session> sessionPool = new HashMap<>();

    @OnOpen
    public void onOpen(Session session, @PathParam(value="userName")String userName) {
    
    
        this.session = session;
        webSockets.add(this);
        sessionPool.put(userName, session);
        System.out.println("【websocket消息】有新用户" + userName +"接入，当前在线总数为:"+webSockets.size());
    }

    @OnClose
    public void onClose() {
    
    
        try {
    
    
            webSockets.remove(this);
        } catch (Exception e) {
    
    
            e.printStackTrace();
        }
        System.out.println("【websocket消息】连接断开，总数为:"+webSockets.size());
    }

    @OnMessage
    public void onMessage(String message,@PathParam(value="userName")String userName) {
    
    
        System.out.println("【websocket消息】收到" + userName + "消息:" + message);
    }

    /**
     * 集体通知
     * @param message
     */
    public void sendAllMessage(String message) {
    
    
        for(WebSocket webSocket : webSockets) {
    
    
            System.out.println("群体通知:"+message);
            try {
    
    
                webSocket.session.getAsyncRemote().sendText("群体通知:"+message);
            } catch (Exception e) {
    
    
                e.printStackTrace();
            }
        }
    }

    /**
     * 单用户通知
     * @param userName
     * @param message
     */
    public void sendOneMessage(String userName, String message) {
    
    
        log.info("站内消息给{}发送了{}",userName,message);
        Session session = sessionPool.get(userName);
        if (session != null) {
    
    
            try {
    
    
                session.getAsyncRemote().sendText(message);
            } catch (Exception e) {
    
    
                e.printStackTrace();
            }
        }
    }

}

3. The client can use postman to initiate a webSocket request.