angular4 父组件和子组件通过服务来通讯

父组件和它的子组件共享同一个服务,可以将这服务理解为全局，同时共用，但是这个服务实例的作用域被限制在父组件和其子组件内，这个组件之外的服务无法访问这个服务。

import { Injectable } from ‘@angular/core‘;
@Injectable()
export class myService {
  list:string[] = [];
  constructor() { }
  append(str:any){
    this.list.push(str);
  }
}

//faher.compnent.ts

import { Component, OnInit } from ‘@angular/core‘; 
import {Service} from "service/Service.service"; 
@Component({ 
selector: ‘app-father‘,
 templateUrl: ‘father.component.html‘,
 styleUrls: [‘father.component.css‘],
 providers:[Service](注入服务) 
})

 export class FatherComponent implements OnInit {
 list:string[] = [];
 constructor(
　　　　private service:Service
) { }
 ngOnInit() {
 　　this.list = this.service.list;
  } }

//faher.compnent.html

<app-child></app-child>
<ul>
  <li *ngFor="let item of list">{{item}}</li>
</ul>

//child.compnent.ts

import { Component, OnInit } from ‘@angular/core‘;
 import {Service} from "service/child.service";
 @Component({
 selector: ‘app-child‘, 
templateUrl: ‘child.component.html‘, 
styleUrls: [‘child.component.css‘] }) 
export class ChildComponent implements OnInit {
 inputText:string = "";
 constructor(
     private service:Service
) { }
 ngOnInit() { }
　　 add(){
 　　this.service.appeend( this.inputText);
　　 this.inputText = "";
 } }

//child.compnent.html

<input type="text" [(ngModel)]="inputText"/> 
<input type="button" value="add" (click)="add()"/>