如何将@Input中的变量传递给Angular2 component>中的服务

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

@Component({
  selector: 'parent-component',
  template: `
    <child-component [inputVariable]="parentVariable"></child-component>
  `
})
export class ParentComponent {
  parentVariable: string = 'Hello from parent';
}

import { Component, Input } from '@angular/core';
import { ChildService } from './child.service';

@Component({
  selector: 'child-component',
  template: `
    <p>{{ childService.childVariable }}</p>
  `,
  providers: [ChildService]
})
export class ChildComponent {
  @Input() inputVariable: string;

  constructor(private childService: ChildService) {
    this.childService.childVariable = this.inputVariable;
  }
}

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

@Injectable()
export class ChildService {
  childVariable: string;
}