如何在运行时确定可注入的angular服务？

// 1. 创建一个服务类
import { Injectable } from '@angular/core';

@Injectable()
export class MyService {
  constructor() { }

  // 提供所需的功能和方法
  doSomething() {
    console.log('Doing something...');
  }
}

// 2. 在模块中注册服务
import { NgModule } from '@angular/core';
import { MyService } from './my.service';

@NgModule({
  providers: [MyService]
})
export class AppModule { }

// 3. 在组件中注入服务
import { Component } from '@angular/core';
import { MyService } from './my.service';

@Component({
  selector: 'app-my-component',
  template: '<button (click)="doSomething()">Do Something</button>'
})
export class MyComponent {
  constructor(private myService: MyService) { }

  doSomething() {
    this.myService.doSomething();
  }
}