Angular 2-简单的HTTP GET from组件无法工作

import { HttpClientModule } from '@angular/common/http';

@NgModule({
  imports: [
    HttpClientModule
  ],
  ...
})
export class AppModule { }

import { HttpClient } from '@angular/common/http';

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

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

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

@Component({
  selector: 'app-root',
  template: `
    <button (click)="getData()">Get Data</button>
    <div>{{ data }}</div>
  `
})
export class AppComponent {
  data: any;

  constructor(private dataService: DataService) { }

  getData() {
    this.dataService.getData().subscribe((response) => {
      this.data = response;
    });
  }
}