檔案下載時檔名在ie和firefox下面表現不一致問題

String agent = request.getHeader("USER-AGENT");
String fileName = desc+".xls";
 if (null != agent && -1 != agent.indexOf("MSIE")){
    fileName = java.net.URLEncoder.encode(fileName, "UTF8");
 }else if (null != agent && -1 != agent.indexOf("Mozilla")){
    fileName = MimeUtility.encodeText(fileName, "UTF8", "B");
 }
 response.setContentType("application/vnd.ms-excel;charset=UTF-8");
 //response.setHeader("Cache-Control", "no-cache");
 response.setHeader("Pragma", "no-cache");
 response.setDateHeader("Expires", 0);
 response.setHeader("Content-disposition" , "attachment; filename=" + fileName);