Angular / rxjs :显示下载进度+等待文件下载完成后再继续

import { Component } from '@angular/core';
import { HttpClient, HttpEventType } from '@angular/common/http';
import { map } from 'rxjs/operators';

@Component({
  selector: 'app-download',
  template: `
    <button (click)="download()">下载文件</button>
    <div *ngIf="progress !== undefined">
      <p>下载进度: {{ progress }}%</p>
    </div>
  `
})
export class DownloadComponent {
  public progress: number;

  constructor(private http: HttpClient) { }

  download() {
    const url = '下载文件的URL地址';
    const fileName = '文件名';
    
    this.http.get(url, { responseType: 'blob', observe: 'events', reportProgress: true })
      .pipe(
        map(event => {
          if (event.type === HttpEventType.DownloadProgress) {
            const percentDone = Math.round(100 * event.loaded / event.total);
            this.progress = percentDone;
          } else if (event.type === HttpEventType.Response) {
            // 下载完成后的处理逻辑
            const blob = new Blob([event.body]);
            const link = document.createElement('a');
            link.href = window.URL.createObjectURL(blob);
            link.download = fileName;
            link.click();
          }
        })
      )
      .subscribe();
  }
}