Angular2中监听数据更新的方法

import { Component, DoCheck } from "@angular/core";
export class LangListUserComponent implements DoCheck {

constructor(private differs: KeyValueDiffers) {
}

ngOnInit() {
 this.objDiffer = {};
 this.list.forEach((elt) => {
  this.objDiffer[elt] = this.differs.find(elt).create(null);
 });
}

ngDoCheck() {
 this.list.forEach(elt => {
  var objDiffer = this.objDiffer[elt];
  var objChanges = objDiffer.diff(elt);
  if (objChanges) {
   objChanges.forEachChangedItem((elt) => {
    if (elt.key === 'prop1') {
     this.doSomethingIfProp1Change();
    }
   });
  }
 });
}

<input type="text" pInputText size="50" [formControl]="term" placeholder="输入搜索条件">

colo = new FormControl();

this.colo.valueChanges.distinctUntilChanged().subscribe((ast) => {
//do something
})