Question

我是Angular的新手，正在尝试弄清楚如何将Angular服务（游戏服务）注入另一个将成为Resolver（游戏解析器）的angular服务中。通常，我的应用程序中仅创建了一个游戏服务实例，并且已成功将其注入到每个组件中，但是当需要我的游戏解析器服务时，即使游戏服务是应该是单身人士。

我尝试在NgModule的'providers'数组中声明这两个服务，以使其同时成为单例服务，并且还尝试了在@Injectable装饰器中声明'providedIn：'root'的方法。，但是在调用游戏解析器服务构造函数时会创建游戏服务的新实例。

//GameResolver.service.ts

    @Injectable({
      providedIn: 'root'
    })
    export class GameResolverService implements Resolve<Game> {
      constructor(private gameService: GameService) {

      }


      resolve(route: ActivatedRouteSnapshot, state: RouterStateSnapshot): Observable<Game> {

          return this.gameService.getGameById(gameId)

      }
    }

//game-resolver.service.spec.ts    

import { TestBed, inject } from '@angular/core/testing';

import { GameResolverService } from './game-resolver.service';

describe('GameResolverService', () => {
  beforeEach(() => {
    TestBed.configureTestingModule({
      providers: [GameResolverService]
    });
  });

  it('should be created', inject([GameResolverService], (service: GameResolverService) => {
    expect(service).toBeTruthy();
  }));
});



//Game.service.ts

import { Injectable } from '@angular/core';
import { Http, Headers } from '@angular/http';
import { Game } from './game';
import { map } from "rxjs/operators";
import { User } from './user';


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

  constructor(private http: Http) {
    console.log('new instance of GameService created');
  }



//app.module.ts

const appRoutes: Routes = [
  ...
  {path:'game', component: GameComponent, data:{depth:3}, resolve: { game: GameResolverService}},
  {path:'endGame', component: EndGameComponent, data:{depth:4}},
  {path:'nextRound', component: NextRoundComponent, data:{depth:5}}
]

@NgModule({
  declarations: [
    ...
  ],
  imports: [
    ...
  ],
  bootstrap: [AppComponent],
  providers: [GameService, GameResolverService]
})


//create-game.component.ts
...
import {GameService} from '../game.service';




@Component({
  selector: 'app-create-game',
  templateUrl: './create-game.component.html',
  styleUrls: ['./create-game.component.css'],

})
export class CreateGameComponent implements OnInit {
  // @HostListener('window:popstate', ['$event'])




  constructor(private gameService: GameService, private router: Router) {
   }


//game.component.ts

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

  game:Game;

  constructor(private gameService: GameService, private router: Router, private socketService: SocketService, private route: ActivatedRoute ) {
    this.game = this.route.snapshot.data['game']
  }
}

关于角度依赖注入的层次结构，我是否不了解？我需要GameService成为应用程序所有部分的单例服务，因此我需要将单例实例注入Game Resolver Service中，而无需创建新实例。

Answer 1

经过大量搜索后，我终于意识到，在使用providers方法的同时，我仍然在@Component装饰器中定义了providedIn: 'root'数组。 Dzhavat Ushev是正确的，您不能同时使用这两个功能。我以为我已经摆脱了所有的providers声明，但是我不知道有一个声明。现在，它可以完美运行。谢谢您的帮助。

在另一个单例服务中创建的Angular单例服务的新实例

1 个答案: