詳解Angular2組件之間如何通信

2019-11-19 16:16:47

字體：大中小

供稿：網(wǎng)友

組件之間的共享可以有好幾種方式

父->子 input 方式

import {Component,Input} from 'angular2/core';@Component({  selector: 'child',  template: `    <h2>child {{content}}</h2>  `})class Child {  @Input() content:string;}@Component({  selector: 'App',  directives: [Child],  template: `    <h1>App</h1>    <child [content]="i"></child>  `})export class App {  i:number = 0;  constructor() {    setInterval(()=> {      this.i++;    }, 1000)  }}

子->父 output 方式

import {Output,EventEmitter,Component} from 'angular2/core';@Component({  selector: 'child',  template: `    <h2>child</h2>  `})class Child {  @Output() updateNumberI:EventEmitter<number> = new EventEmitter();  i:number = 0;  constructor() {    setInterval(()=> {      this.updateNumberI.emit(++this.i);    }, 1000)  }}@Component({  selector: 'App',  directives: [Child],  template: `    <h1>App {{i}}</h1>    <child (updateNumberI)="numberIChange($event)"></child>  `})export class App {  i:number = 0;  numberIChange(i:number){    this.i = i;  }}

子獲得父實(shí)例

如果不了解forwardRef用處的的可以看 #11

@Host 表示這個(gè)Injector必須是host element在這里可以理解為 parent

import {Host,Component,forwardRef} from 'angular2/core';@Component({  selector: 'child',  template: `    <h2>child</h2>  `})class Child {  constructor(@Host() @Inject(forwardRef(()=> App)) app:App) {    setInterval(()=> {      app.i++;    }, 1000);  }}@Component({  selector: 'App',  directives: [Child],  template: `    <h1>App {{i}}</h1>    <child></child>  `})export class App {  i:number = 0;}

父獲得子實(shí)例

子元素指令在父constructor時(shí)是獲取不到的，所以必須在組件的ngAfterViewInit生命周期鉤子后才能獲取，如果對(duì)組件生命周期不了解的話，可以參考#56

import {ViewChild,Component} from 'angular2/core';@Component({  selector: 'child',  template: `    <h2>child {{i}}</h2>  `})class Child {  i:number = 0;}@Component({  selector: 'App',  directives: [Child],  template: `    <h1>App {{i}}</h1>    <child></child>  `})export class App {  @ViewChild(Child) child:Child;  ngAfterViewInit() {    setInterval(()=> {      this.child.i++;    }, 1000)  }}

service 方式

import {Component,Injectable} from 'angular2/core';@Injectable();class KittencupService {  i:number = 0;}@Component({  selector: 'child',  template: `    <h2>child {{service.i}}</h2>  `})class Child {  constructor(public service:KittencupService){  }}@Component({  selector: 'App',  directives: [Child],  providers: [KittencupService],  template: `    <h1>App {{i}}</h1>    <child></child>  `})export class App {  constructor(service:KittencupService) {    setInterval(()=> {      service.i++;    }, 1000)  }}

service EventEmitter方式

import {Component,Injectable,EventEmitter} from 'angular2/core';@Injectable()class KittencupService {  change: EventEmitter<number>;  constructor(){    this.change = new EventEmitter();  }}@Component({  selector: 'child',  template: `<h2>child {{i}}</h2>`})class Child {  public i:number = 0;  constructor(public service:KittencupService){    service.change.subscribe((value:number)=>{      this.i = value;    })  }}@Component({  selector: 'App',  directives: [Child],  providers: [KittencupService],  template: `<h1>App {{i}}</h1><child></child>`})export class App {  i:number = 0;  constructor(service:KittencupService) {    setInterval(()=> {      service.change.emit(++this.i);    }, 1000)  }}

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