[Flex]flex侦听键盘事件代码示例

在监听键盘事件之前，让舞台获得焦点是必要的，加一个单击事件来变通一下

<?xml version="1.0" encoding="utf-8"?> 
<s: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" minWidth="955" 
minHeight="600" creationComplete="init()"> 
<s:layout> 
   <s:BasicLayout/> 
</s:layout> 
<fx:Declarations> 
   <!-- 将非可视元素（例如服务、值对象）放在此处 --> 
</fx:Declarations> 
<fx:Script> 
   <![CDATA[ 
    import spark.core.SpriteVisualElement; 
    import mx.controls.Alert; 
    
    private var sprite:SpriteVisualElement; 
    
    internal function init():void{ 
      sprite = new SpriteVisualElement(); 
      sprite.graphics.beginFill(0xFF0000); 
      sprite.graphics.drawCircle(10,10,30); 
      sprite.graphics.endFill(); 
      this.addElement(sprite); 
     // sprite. 
      sprite.addEventListener(MouseEvent.MOUSE_DOWN,startDragHander); 
      sprite.addEventListener(MouseEvent.MOUSE_UP,stopDragHander); 
      this.addEventListener(KeyboardEvent.KEY_UP,keyHander); 
    } 
    
    internal function startDragHander(evt:MouseEvent):void{ 
     sprite.startDrag(); 
    } 
    
    internal function stopDragHander(evt:MouseEvent):void{ 
     sprite.stopDrag(); 
    } 
    
    internal function doFoucs():void{ 
    stage.focus = this; 
    } 
    
    internal function keyHander(evt:KeyboardEvent):void{ 
     //Alert.show(evt.keyCode.toString()); 
      switch(evt.keyCode){ 
         case 37: 
       sprite.x-=10; 
      break; 
      case 38: 
       sprite.y-=10; 
      break; 
      case 39: 
       sprite.x+=10; 
         break; 
      case 40: 
       sprite.y+=10; 
      break; 
      default: 
      break; 
      } 
    } 
   ]]> 
</fx:Script> 
<s:Button x="539" y="369" label="场景获得焦点" click="doFoucs()"/> 
</s:Application>