如何在Angular6HttpClient中获取响应头

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

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

import { NzNotificationService } from 'ng-zorro-antd';

import { UtilService } from '@/services/util.service';

@Injectable()
export class ApiService {
  async request(method, url, data = {}) {
    const headers = {
      'Content-Type': 'application/json',
      Authorization: `Bearer ${localStorage.getItem('token')}`,
    };
    const trim = s => s === undefined || s === null ? '' : s;
    const args = [
      window['baseUrl'],
      url.replace(/:([^&;/?]+)/g, (...s) => trim(data[s[1]])),
    ].join('/');

    const params = Object.keys(data).reduce((obj, key) => {
      obj[key] = trim(data[key]);
      return obj;
    }, {});

    const optiOns= {
      observe: 'response' as 'response', // 获取完整响应对象
      responseType: 'json'
    };

    try {
      const requestData = {
        url: args,
        method: method,
      };
      console.log(args);

      const respOnse= await this.http[method](args, { ...options, headers, params }).toPromise();
      console.log(response.headers); // 打印响应头
      return response.body;
    } catch (e) {
      console.error(e);
      if (e.status !== 401) {
        // this.notify.create('error', `${e.status}`, e.error.message);
      } else {
        localStorage.clear();
        this.util.navigate(['/user/login']);
      }
      throw e;
    }
  }

  delete = (url) => (data?) => this.request('delete', url, data);
  get = (url) => (data?) => this.request('get', url, data);
  patch = (url) => (data?) => this.request('patch', url, data);
  post = (url) => (data?) => this.request('post', url, data);
  put = (url) => (data?) => this.request('put', url, data);

  constructor(
    private http: HttpClient,
    private notify: NzNotificationService,
    private util: UtilService,
  ) { }
}

async getData(index?) {
  this.loading = true;
  this.currentPage = index;
  this.api.get('accounts')({
    page: this.currentPage,
    'per-page': this.limits
  }).subscribe(resp => {
    console.log(resp.headers); // 打印响应头
    console.log(resp.body); // 打印响应体
    this.loading = false;
    this.data = resp.body;
    this.totalCount = resp.body._meta.totalCount;
  });
}