组件通讯，意在不同的指令和组件之间共享信息。如何在两个多个组件之间共享信息呢。

最近在项目上，组件跟组件之间可能是父子关系，兄弟关系，爷孙关系都有。。。。。我也找找了很多关于组件之间通讯的方法，不同的方法应用在不同的场景，根据功能需求选择组件之间最适合的通讯方式。下面我就总结一下关于组件通讯的N多种方法。

1.父→子 input

parent.ts

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

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

@H_403_55@

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>

@H_403_55@

child.ts

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

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

@H_403_55@

child.html

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

@H_403_55@

结果:

2.子→父 output

parent.ts

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

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

  numberIChange(i:number){
      this.i = i;
  }
}

@H_403_55@

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>

@H_403_55@

child.ts

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

@Component({
  selector: 'page-child',})

export class ChildPage {
  @Output() changeNumber: EventEmitter<number> = new EventEmitter();
  Number: number = 0;
  constructor() {
    setInterval(() => {
      this.changeNumber.emit(++this.Number);
    },1000)
  }
}

@H_403_55@

child.html

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

@H_403_55@

结果：

3.子获得父实例

parent.ts

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

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

@H_403_55@

parent.html

<ion-header>
  <ion-navbar>
    <ion-title>Parent</ion-title>
  </ion-navbar>
</ion-header>

<ion-content padding>
  <h1>parent: {{i}}</h1>
  <page-child></page-child>
</ion-content>

@H_403_55@

child.ts

import { Component,Input,Output,Host,Inject,forwardRef } from '@angular/core';
import{ParentPage} from '../parent/parent';
@Component({
  selector: 'page-child',})
export class ChildPage {
    constructor( @Host() @Inject(forwardRef(() => ParentPage)) app: ParentPage) {
        setInterval(() => {
            app.i++;
        },1000);
    }
}

@H_403_55@

child.html

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

@H_403_55@

结果：

4.父获得子实例

parent.ts

import {ViewChild,Component } from '@angular/core';
import{ChildPage}from '../child/child';

@Component({
  selector: 'page-parent',})
export class ParentPage {
  @ViewChild(ChildPage) child:ChildPage;
    ngAfterViewInit() {
        setInterval(()=> {
            this.child.i++;
        },1000)
    }
}

@H_403_55@

parent.html

<ion-header>
  <ion-navbar>
    <ion-title>Parent</ion-title>
  </ion-navbar>
</ion-header>

<ion-content padding>
  <h1>parent {{i}}</h1>
  <page-child></page-child>
</ion-content>

@H_403_55@

child.ts

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


@Component({
  selector: 'page-child',})
export class ChildPage {
    i:number = 0;
}

@H_403_55@

child.html

<ion-content padding>
<h2>child {{i}}</h2>
</ion-content>

@H_403_55@

结果：

5.service

parent.ts

import { Component } from '@angular/core';
import{myService}from '../child/myService'

@Component({
  selector: 'page-parent',})
export class ParentPage {

i:number=0; @H_403_55@ @H_403_55@

   constructor(service:myService) {
        setInterval(()=> {
            service.i++;
        },1000)
    }
}

@H_403_55@

parent.html

<ion-header>
  <ion-navbar>
    <ion-title>Parent</ion-title>
  </ion-navbar>
</ion-header>

<ion-content padding>
   <h1>parent {{i}}</h1>
   <page-child></page-child>
</ion-content>

@H_403_55@

child.ts

import { Component} from '@angular/core';
import{myService}from "../child/myService"
@Component({
  selector: 'page-child',})
export class ChildPage {
    constructor(public service:myService){
    }
}

@H_403_55@

child.html

<ion-content padding>
<h2>child {{service.i}}</h2>
</ion-content>

@H_403_55@

myService.ts
ps:记得在app.module.ts 加上providers: [KmyService]

import{Injectable } from '@angular/core';
@Injectable()
export class KmyService {
    i:number = 0;
}

@H_403_55@

结果：

6.EventEmitter

myService.ts

import {Component,Injectable,EventEmitter} from '@angular/core';
@Injectable()
export class myService {
    change: EventEmitter<number>;

    constructor(){
        this.change = new EventEmitter();
    }
}

@H_403_55@

parent.ts

import { Component } from '@angular/core';
import{myService}from '../child/myService'

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

@H_403_55@

parent.html

<ion-header>
  <ion-navbar>
    <ion-title>Parent</ion-title>
  </ion-navbar>
</ion-header>

<ion-content padding>
   <h1>parent {{i}}</h1>
   <page-child></page-child>
</ion-content>

@H_403_55@

child.ts

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

import{myService}from "../child/myService"
@Component({
  selector: 'page-child',})
export class ChildPage {

    i:number = 0;

    constructor(public service:myService){
        service.change.subscribe((value:number)=>{
            this.i = value;
        })
    }
    
}

@H_403_55@

child.html

<ion-content padding>
 <h2>child {{i}}</h2>
</ion-content>

@H_403_55@

结果：

7.订阅

parent.ts

import { Component } from '@angular/core';
import{myService}from '../child/myService'

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

@H_403_55@

parent.html

<ion-header>
  <ion-navbar>
    <ion-title>Parent</ion-title>
  </ion-navbar>
</ion-header>

<ion-content padding>
   <h1>parent</h1>
   <page-child></page-child>
</ion-content>

@H_403_55@

child.ts

import { Component,Injectable } from '@angular/core'
import { myService } from "../child/myService"
import { Subscription } from 'rxjs/Subscription';
@Component({
    selector: 'page-child',})
export class ChildPage {
    i:number=0;
    subscription: Subscription;
    constructor(private Service: myService) {
        this.subscription = Service.Status$.subscribe(message => {
            this.i=message;
        });
    }

    ngOnDestroy() {
        this.subscription.unsubscribe();
    }
}

@H_403_55@

child.html

<ion-content padding>
  <h2>child {{i}}</h2> 
</ion-content>

@H_403_55@

myService.ts

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

@Injectable()
export class myService {

    private Source=new Subject<any>();
    Status$=this.Source.asObservable();
    StatusMission(message: any) {
        this.Source.next(message);
    }
}