Flex中本地图片上传及上传文件前的预览

<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" layout="absolute" fontSize="12" creationComplete="init()">
<mx:Script>
<!--[CDATA[
import mx.utils.*;
import flash.net.*;

private var fileReference:FileReference=new FileReference();
private var byteArray:ByteArray;
private var bitmapData:BitmapData;
private var loader:Loader=new Loader();
private function init():void
{
fileReference.addEventListener(Event.COMPLETE,fileReferenceCompleteHandler);
}
private function fileReferenceCompleteHandler(e:Event):void
{
byteArray = fileReference.data;
loader.contentLoaderInfo.addEventListener(Event.COMPLETE,loaderCompleteHandler);
loader.loadBytes(byteArray);
}
private function loaderCompleteHandler(e:Event):void
{
var bitmap:Bitmap = Bitmap(loader.content);
bitmapData = bitmap.bitmapData;
img.source = bitmap;
}
private function fileReferenceSelectHandler(e:Event):void
{
fileReference.load();
}
private function btnClick():void
{
fileReference.browse();
fileReference.addEventListener(Event.SELECT,fileReferenceSelectHandler);
}
]]-->
</mx:Script>
<mx:Panel width="456" height="345" horizontalCenter="0" verticalGap="0" horizontalAlign="center" verticalAlign="middle">
<mx:Image id="img" width="263" height="234"/>
<mx:Button label="选择..." click="btnClick()"/>
</mx:Panel>
</mx:Application>