在angular中如何等待执行服务？

import { Injectable } from '@angular/core';

@Injectable()
export class MyService {
  async fetchData(): Promise<any> {
    return new Promise((resolve, reject) => {
      // 异步操作，比如从服务器获取数据
      setTimeout(() => {
        const data = '这是从服务器获取的数据';
        resolve(data);
      }, 2000);
    });
  }
}

import { Component } from '@angular/core';
import { MyService } from './my.service';

@Component({
  selector: 'app-my-component',
  template: `
    <div>{{ fetchedData }}</div>
  `
})
export class MyComponent {
  fetchedData: any;

  constructor(private myService: MyService) {}

  async ngOnInit() {
    try {
      this.fetchedData = await this.myService.fetchData();
    } catch (error) {
      console.error(error);
    }
  }
}

import { Injectable } from '@angular/core';
import { Observable } from 'rxjs';

@Injectable()
export class MyService {
  fetchData(): Observable<any> {
    return new Observable((observer) => {
      // 异步操作，比如从服务器获取数据
      setTimeout(() => {
        const data = '这是从服务器获取的数据';
        observer.next(data);
        observer.complete();
      }, 2000);
    });
  }
}

import { Component } from '@angular/core';
import { MyService } from './my.service';

@Component({
  selector: 'app-my-component',
  template: `
    <div>{{ fetchedData }}</div>
  `
})
export class MyComponent {
  fetchedData: any;

  constructor(private myService: MyService) {}

  ngOnInit() {
    this.myService.fetchData().subscribe(
      (data) => {
        this.fetchedData = data;
      },
      (error) => {
        console.error(error);
      }
    );
  }
}