var ff:File = File.desktopDirectory.resolvePath("Progress.CSV");
ff.addEventListener(Event.SELECT,exportCSVSelectedHandler);
ff.browseForSave("選擇路徑");

private function exportCSVSelectedHandler(event:Event):void
{
var dir:String = event.target.nativePath;
var writeStream:FileStream = new FileStream();
writeStream.open(new File(dir),FileMode.WRITE);
var content:String = "jhfdklahflaksjdhflkasjhflaskjhlf/n";
writeStream.writeMultiByte(content,'utf-8');
writeStream.close();
}

var content:String = "jhfdklahflaksjdhflkasjhflaskjhlf/n";

var f:FileReference = new FileReference();
f.save(content,"1.csv");