火狐浏览器下载文件保存文件名的乱码问题

String oldname = file.getName().substring(file.getName().indexOf("_")+1); 
String encodefileName = request.getHeader ( "user-agent" ).contains ( "MSIE" ) ? ("="+URLEncoder.encode ( oldfilename, "utf-8") ):("*=utf-8‘‘"+ URLEncoder.encode ( oldfilename, "utf-8") );
response.setHeader ( "Content-disposition", "attachment; filename" + encodefileName);