Flex动态设置Button中的icon指向外网图片源

　　package { import flash.display.BitmapData; import flash.display.Loader; import flash.display.LoaderInfo; import flash.events.Event; import flash.geom.Matrix; import flash.net.URLRequest; import flash.system.LoaderContext; import flash.utils.Dictionary; import mx.containers.accordionClasses.AccordionHeader; import mx.controls.tabBarClasses.Tab; import mx.core.BitmapAsset; import mx.core.UIComponent; public class IconUtility extends BitmapAsset { private static var dictionary:Dictionary; public static function getClass( target:UIComponent, source:String, width:Number = NaN, height:Number = NaN ):Class { if(!dictionary) { dictionary = new Dictionary(false); } //if(source is String) //{ var loader:Loader = new Loader(); loader.load(new URLRequest(source as String), new LoaderContext(true)); //source = loader; //} dictionary[target] = { source:loader, width:width, height:height }; return IconUtility; } public function IconUtility():void { addEventListener(Event.ADDED, addedHandler, false, 0, true) } private function addedHandler(event:Event):void { if(parent) { if(parent is AccordionHeader) { var header:AccordionHeader = parent as AccordionHeader; getData(header.data); } else if(parent is Tab) { var tab:Tab = parent as Tab; getData(tab.data); } else { getData(parent); } } } private function getData(object:Object):void { var data:Object = dictionary[object]; if(data) { var source:Object = data.source; if(data.width > 0 && data.height > 0) { bitmapData = new BitmapData(data.width, data.height, true, 0x00FFFFFF); } if(source is Loader) { var loader:Loader = source as Loader; if(!loader.content) { loader.contentLoaderInfo.addEventListener(Event.CO MPLETE, completeHandler, false, 0, true); } else { displayLoader(loader); } } } } private function displayLoader( loader:Loader ):void { if(!bitmapData) { bitmapData = new BitmapData(loader.content.width, loader.content.height, true, 0x00FFFFFF); } bitmapData.draw(loader, new Matrix(bitmapData.width/loader.width, 0, 0, bitmapData.height/loader.height, 0, 0)); if(parent is UIComponent) { var component:UIComponent = parent as UIComponent; component.invalidateSize(); } } private function completeHandler(event:Event):void { if(event && event.target && event.target is LoaderInfo) { displayLoader(event.target.loader as Loader); } } } }