如何在打字稿上重新连接（重新订阅）到 websocket答案

【问题标题】：How reconnect (resubscribe) to websocket on typescript如何在打字稿上重新连接（重新订阅）到 websocket
【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);
}
}

【问题讨论】：

标签： typescript ionic-framework websocket observable

【解决方案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);
    }
  })  
}

【讨论】：