将抽象Angular服务的特定实现注入到另一个Angular服务中

Question

将特定的子服务注入组件相当简单，但如何注入另一个服务？

示例：父服务

import { Injectable } from '@angular/core';
@Injectable({
providedIn: 'root'
})
export abstract class ParentService {
constructor() { }
abstract testMe(): void;
}

儿童服务

import { ParentService } from "./parent.service";
export class ChildService implements ParentService {
testMe(): void {
console.log('child service');
}
}

成分注入

import { Component } from '@angular/core';
import { ChildService } from './services/child.service';
import { ParentService } from './services/parent.service';
@Component({
selector: 'app-root',
templateUrl: './app.component.html',
styleUrls: ['./app.component.css'],
providers: [
{ 
provide: ParentService, 
useClass: ChildService 
}
]
})
export class AppComponent {
title = 'angular_poc';
constructor(private service: ParentService) {
this.service.testMe();
}
}

子服务方法是执行的，所以这很好，但如何在新服务而不是组件中执行同样的操作？

import { Injectable } from '@angular/core';
import { ParentService } from './parent.service';
@Injectable({
providedIn: 'root' 
})
export class TestService {
constructor(private service: ParentService) {  }
run(){
this.service.testMe();
}
}

可注入中没有提供商

Answer 1

我最终选择了将哪个子服务注入组件本身——组件提供程序。

import { Component } from '@angular/core';
import { ChildService } from './services/child.service';
import { ParentService } from './services/parent.service';
import { TestService } from './services/test.service';
@Component({
selector: 'app-root',
templateUrl: './app.component.html',
styleUrls: ['./app.component.css'],
providers: [
TestService,
{ 
provide: ParentService, 
useClass: ChildService 
}
]
})
export class AppComponent {
title = 'angular_poc';
constructor(private service: TestService) {
this.service.run();
}
}