加载位图，获得bitmapData

var loader:Loader=new Loader();

            loader.contentLoaderInfo.addEventListener(Event.COMPLETE,onComplete);

            try {

                loader.load(new URLRequest("assets/兔年.jpg"));

            }catch(e:Error) {

                Alert.show(e.toString());

            }

private function onComplete(event:Event):void {

            var urlLoader:LoaderInfo=event.target as LoaderInfo;

            var bitmap:Bitmap=urlLoader.content as Bitmap;

        }