读取路由参数?

我是新来的。 我们开始吧:

const routes: Routes = [
  { path: '', redirectTo: '/ru/courses/categories', pathMatch: 'full' },
  { path: ':l/courses/categories', component: CourseCategoriesListComponent }
];

然后我得到了一些可注射的东西,一些负责提供正确翻译的东西:

@Injectable()
export class LanguageService {
  constructor(public activatedRoute: ActivatedRoute) { }

  private readonly map: { [languageCode: string]: (() => TranslatorBase) } = {
    ru: () => new RussianTranslagor()
  };

  getTranslatorForCurrentLanguage(callback: (translatorBase: TranslatorBase) => void): void {
    this.activatedRoute.queryParams.subscribe(
      params => {
        console.log(params);
        // HERE IS THE PROBLEM!!!
        const lang = params['l'];
        if (lang) {
          callback(this.map[lang]());
        }
      }
    );
  }
}

当我运行服务器并到达 localhost:xxxxx queryParams 返回空 params 我看不出这个数字的实际值 :l . 我做错什么了吗?