flex键盘监听事件

<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" layout="absolute" applicationComplete="appComplete();">
<mx:TextArea x="10" y="10" id="t1" width="381" height="387"/>
<mx:Script>
<![CDATA[
import flash.events.KeyboardEvent;
private function myKeyUp(evt:KeyboardEvent):void{
t1.text+= 'evt.charCode='+evt.charCode + 'evt.keyCode='+ evt.keyCode + 'evt.keyLocation='+ evt.keyLocation + " 弹起/n"
}
private function myKeyDown(evt:KeyboardEvent):void{
t1.text= 'evt.charCode='+evt.charCode + 'evt.keyCode='+ evt.keyCode + 'evt.keyLocation='+ evt.keyLocation + "按下/n";
}

private function appComplete():void{
//this.stage.addEventListener(KeyboardEvent.KEY_UP,myKeyUp);
this.stage.addEventListener(KeyboardEvent.KEY_DOWN,myKeyDown);
this.stage.addEventListener(KeyboardEvent.KEY_DOWN,myPress);
}

//下面方法演示每次按下上下左右键头,文本框移动+5像素;
private function myPress(evt:KeyboardEvent):void{
if(evt.keyCode==39){ //右
t2.x=t2.x+5;
}
if(evt.keyCode==38){//上
t2.y=t2.y-5;
}
if(evt.keyCode==40){//下
t2.y=t2.y+5;
}
if(evt.keyCode==37){//左
t2.x=t2.x-5;
}
}

]]>
</mx:Script>
<mx:TextInput x="567" y="149" id="t2"/>
</mx:Application>