flex 里键盘事件

一、
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
      addedToStage="stage.addEventListener(KeyboardEvent.KEY_DOWN, myKeyDown)"   
     click="clickEvt(event)"
     layout="absolute"
     frameRate="6"
     creationComplete="start()" keyFocusChange="testKey(event)"    
  backgroundGradientAlphas="[1.0, 1.0]" backgroundGradientColors="[#990000, #FF9900]">
 <mx:Script source="SnakeMain.as"/> 
二、<?xml version="1.0" encoding="utf-8"?>  
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" 
                layout="absolute" 
                applicationComplete="appComplete();">  
    <mx:Script>  
       <![CDATA[  
           import mx.controls.Alert;  
            import flash.events.KeyboardEvent;  
              
            //监听keyboard事件  
            private function appComplete():void  
            {  
                 this.addEventListener(KeyboardEvent.KEY_DOWN,keyHandler);
                //this.addEventListener(KeyboardEvent.KEY_UP, my