Losing extension when use FileReference download

Question

I need user download JPEG file from my app, however, when user change the file name the saved file will be downloaded without extension.

For Example: I am using File

Answer 1

you just need to use navigateToUrl(ur)

var ur:URLRequest=new URLRequest();
var fr:FileReference=new FileReference();
fr.download(ur,);

"download" method call fileBrowser and then call servlet . then flex can't catch file extension

but "navigateToUrl" called servlet first then servlet call fileBrowser then html can catch file extension