如何将从服务到数组的可观察值转换为Angular2中的ngFor？

import { Observable } from 'rxjs/Observable';
import 'rxjs/add/operator/map';

import { Component } from '@angular/core';
import { DataService } from './data.service';

@Component({
  selector: 'app',
  template: `
    <ul>
      <li *ngFor="let item of data | async">{{ item }}</li>
    </ul>
  `,
  providers: [DataService]
})
export class AppComponent {
  data: Observable<any[]>;

  constructor(private dataService: DataService) {
    this.data = this.dataService.getData();
  }
}