javascript - Angular 继承注入(inject)不同的实例

Question

我有 2 个彼此相同的组件。唯一的区别是它们的名称和一些 html header 。因此我想使用继承。

我创建了一个抽象服务:

export abstract class AbstractFilmListService {

  protected readonly API = WebUtils.RESOURCE_HOST_API + 'film/';


  constructor(protected client: HttpClient) {
  }

  deleteFilm(filmId: number) {
    return this.client.delete(this.API + filmId);
  }

  fetchFilms(): Observable<Film[]> {
    return this.client.get(this.API) as Observable<Film[]>;
  }
}

子类 1:

@Injectable({
  providedIn: 'root'
})
export class FilmListService extends AbstractFilmListService {
  constructor(protected client: HttpClient) {
    super(client);
  }
}

子类2:

@Injectable({
  providedIn: 'root'
})
export class SeriesListService extends AbstractFilmListService{

  protected readonly API: string;

  constructor(client: HttpClient) {
    super(client);
    this.API = WebUtils.SERIES_API;
  }
}

到目前为止一切都还好。但我想用组件做同样的事情:

电影列表组件:

@Component({
  selector: 'app-film-list',
  templateUrl: './film-list.component.html',
  styleUrls: ['./film-list.component.css']
})
export class FilmListComponent implements OnInit {

  constructor(protected client: HttpClient,
              protected router: Router,
              protected snackService: SnackService,
              protected filmListService: FilmListService // <- Problem is here !
              ) {
  }
//....

}

系列列表组件:

 @Component({
  selector: 'app-series-list',
  templateUrl: './series-list.component.html',
  styleUrls: ['./series-list.component.css']
})
export class SeriesListComponent extends FilmListComponent implements OnInit {

  constructor(protected client: HttpClient,
              protected router: Router,
              protected snackService: SnackService,
              protected filmListService: FilmListService // <- Problem is here!
  ) {
    super(client, router, snackService, filmListService);
  }

  ngOnInit() {
  }

}

我想FilmListComponent声明AbstractFilmListService而不是FilmListService，当它开始注入(inject)服务时，它应该注入(inject)FilmListService >.

同样的方式，SeriesListComponent应该声明AbstractFilmListService而不是FilmListService，当它开始注入(inject)服务时，它应该注入(inject)SeriesListService >.

我的意思是这样的:

export class FilmListComponent implements OnInit {

  constructor(
             // ...
              protected filmListService: AbstractFilmListService
              ) {
          this.filmListService = new FilmListService(); // Angular should do  something like this...
  }
//....

}

SeriesListComponent 也是如此:

export class SeriesListComponent implements OnInit {

  constructor(
             // ...
              protected filmListService: AbstractFilmListService
              ) {
          this.filmListService = new SeriesListService(); // Angular should do  something like this...
  }
//....

}

我知道 Angular 不会为每个组件创建新的服务，它使用单例设计模式进行依赖注入(inject)。为了让自己清楚，我写了

"new SeriesListService(), new FilmListService()"

如何为不同的组件注入(inject)不同的实例，即使它们的类型在构造函数中声明相同？

<小时/>

更新

应用程序模块:

@NgModule({
  declarations: [
    AppComponent,
    LoginComponent,
    HeaderComponent,
    HomeComponent,
    UserManagementComponent,
    ActorComponent,
    FilmComponent,
    SeriesComponent,
    ProductComponent,
    SafeUrlPipe,
    FilmListComponent,
    HeroComponent,
    CoverComponent,
    SeasonComponent,
    ChapterComponent,
    SeriesListComponent,
    ],
  imports: [
    BrowserModule,
    FormsModule,
    HttpClientModule,
    RoutingModule,
    TokenModule,
    MaterialModule,
    NgbTimepickerModule,
    HttpInterceptorModule
  ],
  providers: [],
  bootstrap: [AppComponent],
})
export class AppModule {
}

Answer 1

如果它不是一个单例服务，那么在我看来使用 providedIn 就没有多大意义。

但是要回答您的问题，如果您想要此服务的不同实例，您应该在 @Component 注释中提供该服务:

@Component({
  selector: 'app-series-list',
  templateUrl: './series-list.component.html',
  styleUrls: ['./series-list.component.css'],
  providers: [AbstractFilmListService] // <-- will create a new instance for this component
})