angular4自定义组件非input元素实现ngModel双向数据绑定

import { Component,forwardRef } from '@angular/core''@angular/forms'@Component({
selector: 'app-child'<span style="color: #000000">,templateUrl: './child.component.html'<span style="color: #000000">,styleUrls: ['./child.component.css'<span style="color: #000000">],providers: [{
provide: NG_VALUE_ACCESSOR,useExisting: forwardRef(() =><span style="color: #000000"> ChildComponent),multi: <span style="color: #0000ff">true<span style="color: #000000">
}]
})
export class ChildComponent implements ControlValueAccessor {
constructor() { }
_data: any;
add () {
<span style="color: #0000ff">this.childData ++<span style="color: #000000">;
}
change = (value: any) => {}; <span style="color: #008000">//<span style="color: #008000"> 先定义一个方法，很重要，用于接收registerOnChange()方法里传递回来的方法，然后通过这个方法就能通知到外部组件数据更新。
set childData(value: number) { <span style="color: #008000">//<span style="color: #008000"> childData被更改走该方法
<span style="color: #0000ff">this._data =<span style="color: #000000"> value;
<span style="color: #0000ff">this.change(<span style="color: #0000ff">this._data); <span style="color: #008000">//<span style="color: #008000"> 将更新后的数据通知到外部组件
<span style="color: #000000"> }
get childData() { <span style="color: #008000">//<span style="color: #008000"> 页面或者方法里面有调用childData就会走该方法
<span style="color: #0000ff">return <span style="color: #0000ff">this<span style="color: #000000">._data;
}
writeValue(val): <span style="color: #0000ff">void { <span style="color: #008000">//<span style="color: #008000"> 初始化时，获取并监听父组件通过ngModel传递进来的数据
<span style="color: #0000ff">if<span style="color: #000000"> (val) {
<span style="color: #0000ff">this._data =<span style="color: #000000"> val;
}
}
registerOnChange(fn: any): <span style="color: #0000ff">void { <span style="color: #008000">//<span style="color: #008000"> 初始化后，执行该方法，并保存控件接收到 change 事件后，调用的函数
<span style="color: #0000ff">this.change =<span style="color: #000000"> fn;
}
registerOnTouched(fn: any): <span style="color: #0000ff">void<span style="color: #000000"> {
}
}

import { FormsModule } from '@angular/forms'

import { Component,// 这里的组件名为当前组件的名字 multi: = 2

writeValue(val):

writeValue(val): .childData =

registerOnChange(fn: any): { .change =

change = (value: any) => {};

set childData(value: number) { ._data =.change(._data); }

import { Component,multi: = 1.childData ++.change(= (value: any) => {}; writeValue(val): { .childData = { .change =