Angular 4中的WebSocket

Question

我正在用Angular 4和websocket創建聊天應用程序。對於這一點，我已經按照這個Angular websocket tutorial

這裏是WebsocketService源代碼：

import { Injectable } from '@angular/core'; 
import * as Rx from 'rxjs/Rx'; 

@Injectable() 
export class WebsocketService { 
    constructor() { } 

    private subject: Rx.Subject<MessageEvent>; 

    public connect(url): Rx.Subject<MessageEvent> { 
    if (!this.subject) { 
     this.subject = this.create(url); 
     console.log("Successfully connected: " + url); 
    } 
    return this.subject; 
    } 

    private 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); 
    } 

} 

而且這是我的ChatService：

import { Injectable } from '@angular/core'; 
import { Observable, Subject } from 'rxjs/Rx'; 
import { WebsocketService } from './websocket.service'; 

const CHAT_URL = 'ws://echo.websocket.org/'; 

export interface Message { 
    author: string, 
    message: string 
} 

@Injectable() 
export class ChatService { 
    public messages: Subject<Message>; 

    constructor(wsService: WebsocketService) { 
     this.messages = <Subject<Message>>wsService 
      .connect(CHAT_URL) 
      .map((response: MessageEvent): Message => { 
       let data = JSON.parse(response.data); 
       return { 
        author: data.author, 
        message: data.message 
       } 
      }); 
    } 
} 

它工作正常，但我想檢測連接狀態。我想知道連接是否中斷或服務器是否關閉。

對於這一點，我試圖實現WebsocketService類內的isServerOn()功能是這樣的：

isServerOn(): Observable<boolean> { 
    return Observable.of(!!this.subject); 
} 

但一直沒有解決問題。有沒有人惹過同樣的問題？

預先感謝您。

Answer 1

我不知道你想與

return Observable.of(!!this.subject); 

實現我不認爲它做什麼，你認爲它做什麼。 相反，你應該寧可創建自己的BehaviorSubject並返回 對應的可觀測像

isServerOn(): Observable<boolean> { 
    return this.myServerOnSubject.asObservable(); 
} 

在相應的在線/離線碼位置，可以隨後與

this.myServerOnSubject.next(true/false); 

Answer 2

發出的下一個值，我建議你使用您的Angular應用程序中的socket.io-client的類型定義。從您的角度成分

export enum Event { 
    CONNECT = 'connect', 
    DISCONNECT = 'disconnect' 
} 

然後subscribe到您的服務功能：

import { Injectable } from '@angular/core'; 
import { Observable } from 'rxjs/Observable'; 
import { Observer } from 'rxjs/Observer'; 
import { Message } from '../model/message'; 
import { Event } from '../model/event'; 

import * as socketIo from 'socket.io-client'; 

const SERVER_URL = 'https://yourserverhost.com'; 

@Injectable() 
export class SocketService { 
    private socket; 

    public initSocket(): void { 
     this.socket = socketIo(SERVER_URL); 
    } 

    public send(message: Message): void { 
     this.socket.emit('message', message); 
    } 

    public onEvent(event: Event): Observable<any> { 
     return new Observable<Event>(observer => { 
      this.socket.on(event,() => observer.next()); 
     }); 
    } 
} 

定義事件枚舉：然後如下定義服務

export class ChatComponent implements OnInit { 
    constructor(private socketService: SocketService) { } 

    ngOnInit(): void { 
    this.initIoConnection(); 
    } 

    private initIoConnection(): void { 
    this.socketService.initSocket(); 

    this.ioConnection = this.socketService.onMessage() 
     .subscribe((message: Message) => { 
     this.messages.push(message); 
     }); 


    this.socketService.onEvent(Event.CONNECT) 
     .subscribe(() => { 
     console.log('Connected to the server'); 
     }); 

    this.socketService.onEvent(Event.DISCONNECT) 
     .subscribe(() => { 
     console.log('Disconnected'); 
     }); 
    } 
} 

找到完整的聊天項目，這裏使用的是Node.js，WebSockets和Angular：https://github.com/luixaviles/socket-io-typescript-chat