flex中DataGrid中的checkbox

需要重新复写一个CheckBox，在CheckBox被选中后，赋值给相应的data，将状态保存下来即可。 
package comp.control.itemRenderer {   
   import flash.events.Event;   
   import mx.controls.CheckBox;
   public class CheckboxItemRanderer extends CheckBox{
   public function CheckboxItemRanderer() {   
     super();   
     this.addEventListener('change',changeHandler);   
   }   
   private var _data:Object;   
   override public function get data():Object {   
     return _data;   
   }   
   override public function set data(value:Object):void {   
     _data = value;   
     if(_data && _data['selected']){   
      this.selected = true;   
     }else{   
      this.selected = false;   
     }   
   }
   private function changeHandler(event:Event):void{   
     _data['selected'] = this.selected;   
   }   
   }   
   }