flex datagrid checkbox选中项目

<?xml version="1.0" encoding="utf-8"?> 
<mx:Application xmlns:fx="http://ns.adobe.com/mxml/2009"  
   xmlns:s="library://ns.adobe.com/flex/spark"  
   xmlns:mx="library://ns.adobe.com/flex/mx"> 
 
 <fx:Script> 
  <![CDATA[
   import mx.collections.ArrayCollection;
   import mx.controls.Alert;
   
   //数据源
   [Bindable]
   private var dsObjects:ArrayCollection = new ArrayCollection([
    {flag:false,name:"Chen",job:"developer"},
    {flag:false,name:"men",job:"mentor"},
   ]);
   
   /*
   *实现所有项目的全选中过程 
   */
   public function all_click(event:Event):void{
    
    dsObjects = this.dgDistbRecordSearchList.dataProvider as ArrayCollection;
    this.unAll.selected = false;
    for(var i:int = 0 ;i<dsObjects.length;i++){
     dsObjects[i].flag = CheckBox(event.target).selected;
    }
    //重新绑定
    this.dgDistbRecordSearchList.dataProvider = dsObjects;
   }
   /*
   *实现项目反相选中
   */
   public function unAll_click(event:Event):void{
    
    if(CheckBox(event.target).selected){
     
     this.all.selected = false;
     
     dsObjects = this.dgDistbRecordSearchList.dataProvider as ArrayCollection;
     
     for(var i:int = 0 ;i<dsObjects.length;i++){
      dsObjects[i].flag = !dsObjects[i].flag;
     }
     //重新绑定
     this.dgDistbRecordSearchList.dataProvider = dsObjects;
    }
   }
   
   //显示被选中项目的名称
   private function showSelectedName():void{
    var ac:ArrayCollection = this.dgDistbRecordSearchList.dataProvider as ArrayCollection;
    var selectedNames:String = "选中项目名称为："
    
    for(var i:int = 0;i<ac.length;i++){
     if(ac[i].flag == true){
      selectedNames += ac[i].name + " ";
     }
    }
    
    Alert.show(selectedNames);
   }
  ]]> 
 </fx:Script> 
 <mx:VBox> 
  <mx:DataGrid /> 
  
 </mx:VBox> 
 
</mx:Application>