为啥 JS WebSocket 在 sparkjava 中会卡在 CONNECTING 上？

Posted 2023-02-16

【中文标题】为啥 JS WebSocket 在 sparkjava 中会卡在 CONNECTING 上？

【英文标题】：Why does JS WebSocket get stuck on CONNECTING in sparkjava?为什么 JS WebSocket 在 sparkjava 中会卡在 CONNECTING 上？

【发布时间】：2021-02-10 04:11:43

【问题描述】：

这是我的 websocket 代码：

@WebSocket
public class SocketServer 
    BetterLogger logger = new BetterLogger(Main.logger) 
        loggerName = "socket-server";
    ;
    public static class ConnectionInit 
        String tty;
        String device;
    

    static class ConnectionOpenResponse 
        String tty;
    

    @OnWebSocketConnect
    public void onConnect(Session user) throws Exception 
        Main.logger.info("Websocket connected!");
    

    @OnWebSocketClose
    public void onClose(Session user, int statusCode, String reason) 
        Main.logger.info("Websocket disconnected!");
        Main.sessions.closeSession(user);
    

    @OnWebSocketMessage
    public void onMessage(Session user, String message) 
        Main.logger.info("Recevied websock connection: " + message);
        
        try 
            if (Main.sessions.contains(user)) 
                // treat as raw buffer
                Main.sessions.write(user, message);
            
            else 
                ConnectionInit heartbeat = Main.gson.fromJson(message, ConnectionInit.class);
                String s = Main.config.getTTY(heartbeat.device + '.' + heartbeat.tty);

                // make sure that the tty exists in config
                if (s == null)
                    user.close(400, "Invalid device/tty!");

                // get UUID
                Main.sessions.newSession(s, user);

                logger.info("created session (" + user + ") with dev " + heartbeat.device + ":" + heartbeat.tty);
                user.getRemote().sendString(Main.gson.toJson(new ConnectionOpenResponse() 
                    tty = s;
                , ConnectionOpenResponse.class));
            
        
        catch (SessionException e ) 
            user.close(500, e.getMessage());
        
        catch (JsonSyntaxException e) 
            user.close(400, e.getMessage());
        
        catch (IOException e) 
            // wtf
        
    

我已经在我的Main 类中正确注册了它，当我尝试使用websocat 连接到它时，一切似乎都运行良好，我可以发送数据并且一切正常。但是，一旦我创建了一个网页，websocket 就永远不会打开：

console.log("ws://" + location.hostname + ":" + location.port + "/device");
const socket = new WebSocket("ws://" + location.hostname + ":" + location.port + "/device");
var term = new Terminal();

term.open(document.getElementById('terminal'));
term.write('Press enter to re-flush buffers\n');

//while(socket.readyState !== 1);
//console.log("connected!");

socket.send("testdata");

term.onData( (data) => 
    console.log(data);
    if (data.charCodeAt(0) == 13)
        socket.send('\n');
    socket.send(data);
);

// Listen for messages
socket.addEventListener('message', function (event) 
    term.write(event.data);
);

现在，代码打印出正确的 URL (ws://localhost:16838/device)，但是，它卡在 CONNECTING，并引发以下错误（我预计这是因为它仍在连接）：

Uncaught DOMException: Failed to execute 'send' on 'WebSocket': Still in CONNECTING state.

查看我的服务器日志，我可以看到它确实打印了Websocket connected!，这甚至没有任何意义。解决我的 JS websocket 客户端卡住的原因有什么帮助吗？

【参考方案1】：

原来你需要添加打开事件，否则它实际上并没有打开