问如何使用httpClient在Angular7中封装请求管理器？

EN

 public getFocusAreaDataWithHttpClient() {

    this.http.get(Api.focusAreaApi).subscribe({
      next(response) {
        console.log("httpClient handle data");
        console.dir(response);
      },
      error(err) {
        console.error("Error: " + err);
      },
      complete() {
        console.log("Completed");
      }
    });
  }

export class ApiManager {
  constructor(private http: HttpClient) {}
// define request header , content-Type , auth token ,and some common config here
// and there should be 2 method - get and post

}

apiManager.get(apiurl,parameters).subscript...
apiManager.post(apiurl,parameters).subscript...