Angular使用ControlValueAccessor创建自定义表单控件

export interface ControlValueAccessor {
 writeValue(obj: any) : void
 registerOnChange(fn: any) : void
 registerOnTouched(fn: any) : void
}

writeValue(value: any): void {
 this._renderer.setProperty(this._elementRef.nativeElement, 'value', value);
}

registerOnChange(fn: (_: any) => void): void {
 this._onChange = fn;
}

registerOnTouched(fn: any): void {
 this._onTouched = fn;
}

setDisabledState(isDisabled: boolean): void {
 this._renderer.setProperty(this._elementRef.nativeElement, 'disabled', isDisabled);
}

export abstract class AbstractValueAccessor implements ControlValueAccessor {
 
 private _value: any = '';
 
 get value(): any {
 return this._value;
 }

 set value(v: any) {
 if (v !== this._value) {
  this._value = v;
  this.onChange(v);
  this.onTouched();
 }
 }

 writeValue(value: any) {
 this._value = value;
 }

 onChange = (_) => {};
 onTouched = () => {};

 registerOnChange(fn: (_: any) => void): void {
 this.onChange = fn;
 }

 registerOnTouched(fn: () => void): void {
 this.onTouched = fn;
 }
}

export function MakeProvider(type: any): { provide: any, useExisting: any, multi: boolean} {
 return { provide: NG_VALUE_ACCESSOR, useExisting: forwardRef(() => type), multi: true };
}