Angular 4 组件通信

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

@Component({
  selector: 'page-parent',
  templateUrl: 'parent.html',
})
export class ParentPage {
  i: number = 0;
  constructor() {
    setInterval(() => {
      this.i++;
    }, 1000)
  }
}

parent.html<ion-header>
  <ion-navbar>
    <ion-title>Parent</ion-title>
  </ion-navbar>
</ion-header>

<ion-content padding>
  <h2>Parent</h2>
  <page-child [content]="i"></page-child>
</ion-content>

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

@Component({
  selector: 'page-child',
  templateUrl: 'child.html',
})
export class ChildPage {
@Input() content:string;
  constructor() {
  }
}

child.html

<ion-content padding>
child:{{content}}
</ion-content>

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

@Component({
  selector: 'page-parent',
  templateUrl: 'parent.html',
})
export class ParentPage {
  i: number = 0;
  numberIChange(i:number){
      this.i = i;
  }
}

parent.html
<ion-header>
  <ion-navbar>
    <ion-title>Parent</ion-title>
  </ion-navbar>
</ion-header>

<ion-content padding>
  <h2>Parent:{{i}}</h2>
  <page-child (changeNumber)="numberIChange($event)"></page-child>
</ion-content>

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

@Component({
  selector: 'page-child',
  templateUrl: 'child.html',
})
export class ChildPage {
  @Output() changeNumber: EventEmitter<number> = new EventEmitter();
  Number: number = 0;
  constructor() {
    setInterval(() => {
      this.changeNumber.emit(++this.Number);
    }, 1000)
  }
}

child.html

<ion-content padding>
     child
</ion-content>