Non US-ASCII characters in download file names

Question

I am trying to implement a simple file download in a JSP, and trying to get IE, Firefox and Opera to all display and handle non US-ASCII characters in the suggested download file name. Only concerned with Windows platform for now. Here's the code I am currently using:
String agent = request.getHeader("USER-AGENT");
if (null != agent && -1 != agent.indexOf("MSIE"))
String codedfilename = URLEncoder.encode(cfrfilename, "UTF8");
response.setContentType("application/x-download");
response.setHeader("Content-Disposition","attachment;filename=" + codedfilename);
else if (null != agent && -1 != agent.indexOf("Mozilla"))
String codedfilename = MimeUtility.encodeText(cfrfilename, "UTF8", "B");
response.setContentType("application/x-download");
response.setHeader("Content-Disposition","attachment;filename=" + codedfilename);
else
response.setContentType("application/x-download");
response.setHeader("Content-Disposition","attachment;filename=" + cfrfilename);
}This URL encodes the file name if the browser is IE, MIME encodes it if the browser is Mozilla, and sends plain UTF-8 (the encoding of the JSP) for all other browsers. I get "cfrfilename" from translated properties files, and the string can contain characters from any character set - Chinese, Thai, Korean, etc.
This code works correctly for IE - the file name is displayed correctly in the file Save as dialog, and it is saved correctly on disk, no matter which character set is used.
For Firefox, the file name is displayed correctly in the file Save as dialog, but it is only saved correctly to disk if the file name is in a character set supported by the system locale. This seems to be a known Firefox bug (not fully using the Windows Unicode APIs), so nothing I can do about that.
Nothing seems to work for Opera, however - I cannot get the file name to display correctly in the file Save as dialog, no matter which method I use (I have tried URL encoding and MIME encoding in addition to the plain UTF-8).
Has anybody implemented something similar that works for at least these 3 browsers?

Answer 1

I tested your code today,
                     dialog           save           open
Firefox 1.5          OK                 OK               OK
IE 6.0                OK                 OK                NGdailog: filename show in download popup dialog
save: save to disk from dialog
open: open directly from dailog