flex event捕获的两种方法

<?xml version="1.0" encoding="utf-8"?>
<s:WindowedApplication xmlns:fx="http://ns.adobe.com/mxml/2009" 
					   xmlns:s="library://ns.adobe.com/flex/spark" 
					   xmlns:mx="library://ns.adobe.com/flex/mx"
					   creationComplete="initAppHandler()">
	<fx:Script>
		<![CDATA[
			import flash.utils.getTimer;
			
			import mx.events.FlexEvent;

			private var itemArray:Array = new Array;
			private var num:Number = 20;
			protected function initAppHandler():void
			{
				for(var i:int=0;i<num;i++){
					var item:Item = new Item();
					itemArray.push(item);
					addElement(itemArray[i]);
					itemArray[i].txt.text = i;
					itemArray[i].x = i*120;
					//trace(itemArray[i]);
				}
				addEventListener(MouseEvent.CLICK,onClick);
				addEventListener(MouseEvent.MIDDLE_CLICK,onMidClick);
			}
			
			protected function onClick(event:MouseEvent):void{
				//trace(event.target +"\t");
				//trace(event.currentTarget);
				var t:uint = getTimer();
				
				var temp:String = String(event.target);
				var aa:Array = (temp.split(".B"));
				if(aa.length > 1){
					var bb:Array = aa[1].split(".");
					var obj:Object = event.target;
					for(var i:int=0; i<bb.length;i++){ obj = obj.parent; }
					//trace(obj);					
				}
				trace("aa:");
				trace(getTimer()-t);
			}	
			
			protected function onMidClick(event:MouseEvent):void{
				var t:uint = getTimer();
				
				var temp:String = String(event.target);
				var aa:Array = (temp.split(".B"));
				for(var i:int=0; i<num; i++){
					if(itemArray[i] == aa[0]) { 
					//trace(itemArray[i]);
					}
				} 
				trace("bb:");
				trace(getTimer()-t);
			}
		]]>
	</fx:Script>
</s:WindowedApplication>

 第一个全部在0毫秒，第二个偶尔为1毫秒。