无法在我的angular应用程序中下载pdfs

import { Injectable } from '@angular/core';
import { HttpClient, HttpHeaders } from '@angular/common/http';
import { Observable } from 'rxjs';

@Injectable({
  providedIn: 'root'
})
export class DownloadService {
  constructor(private http: HttpClient) {}

  downloadPDF(url: string): Observable<Blob> {
    const headers = new HttpHeaders().set('Accept', 'application/pdf');
    return this.http.get(url, { headers, responseType: 'blob' });
  }
}

import { Component } from '@angular/core';
import { DownloadService } from './download.service';

@Component({
  selector: 'app-root',
  template: `
    <button (click)="downloadPDF()">下载PDF</button>
  `
})
export class AppComponent {
  constructor(private downloadService: DownloadService) {}

  downloadPDF() {
    const pdfUrl = 'https://example.com/path/to/file.pdf';
    this.downloadService.downloadPDF(pdfUrl).subscribe(blob => {
      const url = window.URL.createObjectURL(blob);
      const a = document.createElement('a');
      a.href = url;
      a.download = 'file.pdf';
      a.click();
      window.URL.revokeObjectURL(url);
    });
  }
}