Angular2 -让组件等待服务完成数据获取，然后呈现数据

// 服务代码
import { Injectable } from '@angular/core';
import { HttpClient } from '@angular/common/http';
import { Observable } from 'rxjs';

@Injectable()
export class DataService {
  constructor(private http: HttpClient) {}

  getData(): Observable<any> {
    return this.http.get('https://example.com/api/data');
  }
}

// 组件代码
import { Component, OnInit } from '@angular/core';
import { DataService } from './data.service';

@Component({
  selector: 'app-data',
  template: `
    <div *ngIf="data$ | async as data">
      {{ data }}
    </div>
  `,
})
export class DataComponent implements OnInit {
  data$: Observable<any>;

  constructor(private dataService: DataService) {}

  ngOnInit() {
    this.data$ = this.dataService.getData();
  }
}