在Angular中，可以使用Promise或Observable来等待服务响应。

使用Promise的示例代码如下：

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

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

  getData(): Promise {
    return new Promise((resolve, reject) => {
      this.http.get('https://api.example.com/data').subscribe(
        (response) => {
          resolve(response);
        },
        (error) => {
          reject(error);
        }
      );
    });
  }
}

在组件中使用DataService的示例代码如下：

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

@Component({
  selector: 'app-root',
  template: `
    
{{ data }}
  `
})
export class AppComponent {
  data: any;

  constructor(private dataService: DataService) { }

  ngOnInit() {
    this.dataService.getData().then(
      (response) => {
        this.data = response;
      },
      (error) => {
        console.error(error);
      }
    );
  }
}

使用Observable的示例代码如下：

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

在组件中使用DataService的示例代码如下：

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

@Component({
  selector: 'app-root',
  template: `
    
{{ data }}
  `
})
export class AppComponent {
  data: any;

  constructor(private dataService: DataService) { }

  ngOnInit() {
    this.dataService.getData().subscribe(
      (response) => {
        this.data = response;
      },
      (error) => {
        console.error(error);
      }
    );
  }
}

这些示例中，DataService负责发送HTTP请求并返回数据，组件则调用DataService的方法来获取数据并处理响应或错误。