下載文件到本地

public function downLoad(sourceurl:String,targetfile:String):void{     var loader:URLLoader = new URLLoader();     loader.dataFormat = URLLoaderDataFormat.BINARY;     loader.addEventListener(Event.COMPLETE,      function(e:Event):void      {       var airf:File =File.applicationStorageDirectory.resolvePath(targetfile);       trace(airf.nativePath);       //trace(airf.url);       var fs:FileStream = new FileStream();       fs.open(airf, FileMode.WRITE);       fs.writeBytes(loader.data);       fs.close();       airf.downloaded = true;                 //打開此下載完成的文件       airf.openWithDefaultApplication();      });     loader.addEventListener(ProgressEvent.PROGRESS,function(e:ProgressEvent):void{      trace(e.bytesLoaded/e.bytesTotal+"/"+100);     });     var req:URLRequest = new URLRequest(sourceurl);     loader.load(req);    }