Question

Angular DI Multi Provider机制保证某种顺序吗？

示例：

const TOKEN: OpaqueToken = new OpaqueToken('token');

@Injectable() 
class MyService (@Inject(TOKEN) deps: any[]) {/* What is order of deps? */}

@NgModule ({
  providers: [ 
    {provide: TOKEN, multi: true, useValue: 1},
    {provide: TOKEN, multi: true, useValue: 2},
    {provide: TOKEN, multi: true, useValue: 3},
    MyService
})
class MyModule {}

Answer 1

如果你需要在组件X中注入类A，例如，它依赖于其他类，最好的方法是在类A中注入这些类。在组件X中，你仍然需要声明所有的服务。例如：组件X：

import { Component } from '@angular/core';

import {
  CarService, CarService2, CarService3,
  EngineService, EngineService2, TiresService
} from './car.services';

car.services.ts

import { Injectable } from '@angular/core';

/// Model ///
export class Car {
}

export class Engine {
}

export class Tires {
}

//// Engine services ///
@Injectable()
export class EngineService {
}

@Injectable()
export class EngineService2 {
}

//// Tire services ///
@Injectable()
export class TiresService {
}

/// Car Services ///
@Injectable()
export class CarService {
  id = 'C1';
  constructor(
    protected engineService: EngineService,
    protected tiresService: TiresService) { }
}

@Injectable()
export class CarService2 extends CarService {
  id = 'C2';
  constructor(
    protected engineService: EngineService,
    protected tiresService: TiresService) {
    super(engineService, tiresService);
  }
}

@Injectable()
export class CarService3 extends CarService2 {
  id = 'C3';
  constructor(
    protected engineService: EngineService,
    protected tiresService: TiresService) {
    super(engineService, tiresService);
  }

}

https://stackblitz.com/angular/vomexgeqgdj?file=src%2Fapp%2Fcar.services.ts

Angular Multi Provider依赖顺序

1 个答案: