角多提供者依赖顺序

Question

角DI多提供者机制是否保证某种顺序？

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

我会答应的。虽然我找不到确切的文件可以说。然而，根据个人经验，我可以说，它们总是按照相同的顺序提供的。我们在整个应用程序中使用多个HttpInterceptors以及一些可注入的操作，它们总是按照提供的顺序注入。而且，由于伊尼蒂里泽和拦截器是以这种方式提供的，所以我认为这更正确。您不会希望您的HTTP_拦截器按随机顺序提供。

Answer 2

如果您需要在组件X中注入类A，例如，这取决于其他类，最好的方法是将这些类注入到组件X中的A类中，在组件X中，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