如何在打字稿上重新连接（重新订阅）到 websocket

Posted 2023-02-16

【中文标题】如何在打字稿上重新连接（重新订阅）到 websocket

【英文标题】：How reconnect (resubscribe) to websocket on typescript

【发布时间】：2018-07-21 17:06:34

【问题描述】：

我有一个 Ionic3 应用程序，它在某个视图上连接视图进入并订阅 websocket 可观察/观察者服务：

subscribtion: Subscription;


ionViewDidEnter() 
    this.subscribtion =  this.socket.message.subscribe(msg => 
    let configs = <Configs>msg.data 
    this.inputs = configs.inputs;
  );
  this.socket.message.next(this.enterMessage);

然后，在离开视图时，取消订阅：

ionViewWillLeave() 
  this.socket.message.next(this.quitMessage);
  this.subscribtion.unsubscribe();

但是如果我重新进入视图，它不会重新连接到 websocket。我该怎么做？

这里是socket和websocket.ts：

@Injectable()
export class SocketProvider 

public message: Subject<Message>;

  constructor(private socket: WebsocketProvider, @Inject('server') private server) 
    console.log('Hello SocketProvider Provider');
    let wsAddr = this.server.webSocketUrl();
    this.message = <Subject<Message>>socket
    .connect(wsAddr)
    .map((response: MessageEvent): Message => 
        let data = JSON.parse(response.data);
        return data;
    )
  

  


private subject: Rx.Subject<MessageEvent>;

public connect(url): Rx.Subject<MessageEvent> 
  if (!this.subject) 
    this.subject = this.create(url);
    //console.log('successfully Connnect: ' + url);
  
  return this.subject;


public create(url): Rx.Subject<MessageEvent> 
let ws = new WebSocket(url);

let observable = Rx.Observable.create(
  (obs: Rx.Observer<MessageEvent>) => 
    ws.onmessage = obs.next.bind(obs);
    ws.onerror = obs.error.bind(obs);
    ws.onclose = obs.complete.bind(obs);
    return ws.close.bind(ws);
  
)

let observer = 
  next: (data: Object) => 
    if (ws.readyState === WebSocket.OPEN) 
      ws.send(JSON.stringify(data));
    
  


return Rx.Subject.create(observer, observable);

【参考方案1】：

我找到了解决办法：

我将 socket.ts 中构造函数中的代码移动到我在 IonViewEnter() 中调用的连接函数中并重新初始化 WebSocketProvider 对象：

constructor(private socket: WebsocketProvider, @Inject('server') private server) 
  console.log('Hello SocketProvider Provider');


connect() 
  console.log("try to connect eb socket");
  this.socket = new WebsocketProvider;
  let wsAddr = this.server.webSocketUrl();
  //let wsAddr = 'ws://192.168.0.110:8181';
  this.message = <Subject<Message>>this.socket
  //.connect('wss://echo.websocket.org')
  .connect(wsAddr)
  .map((response: MessageEvent): Message => 
    try 
      let data = JSON.parse(response.data);
      return data;
    catch(e) 
      alert(e);
      console.log("receive invalid JSON message: ");
      console.log(response.data);
    
  )