Angular -无法使用.subsribe将json数据存储在变量中

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

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

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

// 在组件中使用
import { Component, OnInit } from '@angular/core';
import { DataService } from './data.service';

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

  constructor(private dataService: DataService) {}

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

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

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

  getData(): Promise<any> {
    return this.http.get<any>('api/data').toPromise();
  }
}

// 在组件中使用
import { Component, OnInit } from '@angular/core';
import { DataService } from './data.service';

@Component({
  selector: 'app-data',
  template: `
    <div>{{ data }}</div>
  `,
})
export class DataComponent implements OnInit {
  data: any;

  constructor(private dataService: DataService) {}

  ngOnInit() {
    this.dataService.getData().then((result) => {
      this.data = result;
    });
  }
}