Question

在angular2中，

update.service.ts

      public _progress$: Observable<number>;
      private _progress: number = 0;
      private _progressObserver: Observer<number>;
      constructor(private _http:Http, private _configurationService: ConfigurationService,private _authenservice:AuthenticationService) {
        this._progress$ = new Observable(observer => {
          this._progressObserver = observer
        });
      }
    ....
 uploadVideo(file:File):Promise<Video> {
    return new Promise((resolve, reject) => {
      let formData: FormData = new FormData(),
       authenCode = this._authenservice.authenticate(),
        xhr: XMLHttpRequest = new XMLHttpRequest();
      console.log('getVideos:authenCode is' + authenCode);
      let path = this._configurationService.getAPI('API_VIDEOMANAGEMENT_UPLOAD');
      console.log('upload video to:' + path);
      xhr.open('POST', path, true);
      xhr.setRequestHeader('X-Requested-With', 'XMLHttpRequest');
      xhr.setRequestHeader('Content-Type', 'multipart/form-data');
      xhr.onreadystatechange = () => {
        if (xhr.readyState === 4) {
          if (xhr.status === 200) {
            console.log('xhr status 200');
            resolve(<Video>JSON.parse(xhr.response));
          } else {
            console.log('xhr status rejected:'+xhr.status);
            reject(xhr.response);
          }
        }
      };
      xhr.upload.onprogress = (event) => {
        this._progress = Math.round(event.loaded / event.total * 100);
        this._progressObserver.next(this._progress);
      };
      formData.append("file", file, file.name);
      xhr.send(formData);
    });
  }

在另一个组件home.component.ts

中

 private  _uploadProgressStatus:Observable<number>;
 constructor(private _uploadService:UploadService) {
    this._uploadProgressStatus = this._uploadService._progress$; 
 this._uploadProgressStatus.subscribe(
  data => {
    console.log('progress = '+data/100);
  }); //if subscribe to this._uploadProgressStatus, no values are received...
this._uploadService._progress$.subscribe(
  data => {
    console.log('progress = '+data/100);
  });
  } // if subscribe to this._uploadService._progress$ ,numbers are received.

任何想法是什么原因？

Answer 1

制作可观察的.share()

    this._progress$ = new Observable(observer => {
      this._progressObserver = observer
    }).share();

需要导入运营商;

import 'rxjs'

或

import 'rxjs/add/operator/share'

为什么将Observable分配给另一个Observable，后者不接收任何数据？

1 个答案: