c# http文件上传

        /// <summary>
        /// 上传文件的api
        /// </summary>
        [HttpPost]
        public string UploadFile(op_client_billfile_info model)
        {
            string path = AppDomain.CurrentDomain.BaseDirectory + "BillFile";
            path += model.path;
            if (!Directory.Exists(path))
                Directory.CreateDirectory(path);
            model.filename = ExistFile(path, model.filename.Replace(" ", ""));

            MemoryStream ms = new MemoryStream(model.by);
            FileStream fs = new FileStream(path + "\\" + model.filename, FileMode.OpenOrCreate);
            ms.WriteTo(fs);
            ms.Close();
            fs.Close();
            return model.filename;
        }
        /// <summary>
        /// 文件名重复加（1）
        /// </summary>
        [NonAction]
        private string ExistFile(string path, string filename)
        {
            int count = 1;
            //在重复名称后加（序号）
            while (File.Exists(path + "\\" + filename))
            {
                if (filename.Contains(")."))
                {
                    int start = filename.LastIndexOf("(");
                    int end = filename.LastIndexOf(").") - filename.LastIndexOf("(") + 2;
                    filename = filename.Replace(filename.Substring(start, end), string.Format("({0}).", count));
                }
                else
                {
                    filename = filename.Replace(".", string.Format("({0}).", count));
                }
                count++;
            }
            return filename;
        }

        /// <summary>
        /// 账单文件信息的id
        /// </summary>        
        public int bid { get; set; }
        /// <summary>
        /// 文件名
        /// </summary>        
        public string filename { get; set; }
        /// <summary>
        /// 放在服务器的路径
        /// </summary>        
        public string path { get; set; }
        /// <summary>
        /// 文件
        /// </summary>
        public byte[] by { get; set; }

        /// <summary>
        /// 保存文件
        /// url 文件地址（iis）；path 保存地址；fileName 保存文件名
        /// </summary>
        private void DownloadFile(string url, string path, string fileName)
        {
            Stream sm = WebRequest.Create(url).GetResponse().GetResponseStream();
            FileStream fs = new FileStream(path + "\\" + fileName, FileMode.OpenOrCreate);
            sm.CopyTo(fs);
            sm.Close();
            fs.Close();
        }