asp.net 上传/下载/新建文件夹

上传代码：
string fullname = FileUpload1.FileName.ToString();
            string url = FileUpload1.PostedFile.FileName.ToString();
            string typ = FileUpload1.PostedFile.ContentType.ToString();
            string typ2 = fullname.Substring(fullname.LastIndexOf(".")+ 1);
            int size = FileUpload1.PostedFile.ContentLength;
            string upload_file = Server.MapPath("./upload/") + Resumeid + "/" + fullname;
 try
            {
                FileUpload1.PostedFile.SaveAs(upload_file);
            }
            catch
            {
                //error message
            }

下载代码：

if (File.Exists(filePath))
            {
                FileInfo file = new FileInfo(filePath);
                Response.ContentEncoding = System.Text.Encoding.GetEncoding("UTF-8"); //解决中文乱码
                Response.AddHeader("Content-Disposition", "attachment; filename=" + filename.ToString().Trim()); //解决中文文件名乱码   
                Response.AddHeader("Content-length", file.Length.ToString());
                Response.ContentType = "appliction/octet-stream";
                Response.WriteFile(file.FullName);
                Response.End();
            }

创建新文件夹代码：

string CreatePath = Server.MapPath("./upload/") + folder_name.toString();
            if (!Directory.Exists(CreatePath))
            {
                Directory.CreateDirectory(CreatePath);
            }