angular6：注入服务时，实际注入的服务不是我请求的服务

Question

以下是我创建的服务：

HttpSiteLangService.ts

@Injectable({providedIn: 'root'})
export class HttpSiteLangService extends HttpSiteService<SiteLangConfigEntity> {...

HttpSiteService.ts

@Injectable({providedIn: 'root'})
export class HttpSiteService<E> extends HttpApiConfigService<E> {...

HttpApiConfigService.ts

@Injectable({providedIn: 'root'})
export class HttpApiConfigService<E> extends HttpApiService {...

HttpApiService.ts

@Injectable({providedIn: 'root'})
export class HttpApiService {

  constructor(private httpClient: HttpClient) {
  }
...

然后我尝试将HttpSiteLangService注入组件：

export class SiteLangListComponent implements OnInit {
  constructor(public httpService: HttpSiteLangService) {
    console.log(httpService)
  }
...

但是注入是HttpApiService，而不是HttpSiteLangService console log image