while (true)
            {
                path = getDirectory(sServerDir);//修改
                string directory = Path.Combine(sServerDir, path);
                if (!Directory.Exists(directory))
                {
                    Directory.CreateDirectory(directory);
                }
                sFileName=new Random().Next().ToString() + "_" + sFileName;
                string sFilePath = System.IO.Path.Combine(directory, sFileName);

                if (System.IO.File.Exists(sFilePath))
                {
                    iCounter++;
                    sFileName = System.IO.Path.GetFileNameWithoutExtension(oFile.FileName) + "_" + iCounter + "." + sExtension;
                    iErrorNumber = 201;
                }
                else
                {
                    oFile.SaveAs(sFilePath);
                    break;
                }
            }

 /// <summary>
        /// 获取文件夹路径
        /// </summary>
        /// <param name="path">路径</param>
        /// <returns></returns>
        private string getDirectory(string path)
        {
            string directoryName = DateTime.Now.ToString("yyyyMMdd");//文件夹名称，每天一个
            string filePath = Path.Combine(path, directoryName);
            if (!Directory.Exists(filePath))
            {
                return Path.Combine(directoryName, getNumber(1));
            }
            return Path.Combine(directoryName, getPath(Directory.GetDirectories(filePath)));
        }

/// <summary>
        /// 获取文件夹中的文个数件少于1000的文件夹名称
        /// </summary>
        /// <param name="info"></param>
        /// <returns></returns>
        private string getPath(string[] info)
        {
            DirectoryInfo directoryInfo = null;
            string fileName = string.Empty;

            if (info == null)
            {
                return null;
            }
            if (info.Length <= 0)
            {
                return getNumber(1);
            }
            for (int i = 0; i < info.Length; i++)
            {
                directoryInfo = new DirectoryInfo(info[i]);
                if (directoryInfo.Exists)
                {
                    if (directoryInfo.GetFiles().Length < 1000)
                    {
                        fileName = info[i];
                        break;
                    }
                }
            }
            if (string.IsNullOrEmpty(fileName))
            {
                return getNumber(int.Parse(info.ToList<string>().Max(s => s.Substring(s.LastIndexOf("\\") + 1).TrimStart('0'))) + 1);
            }
            else
            {
                return fileName.Substring(fileName.LastIndexOf("\\")+1);
            }
        }


 /// <summary>
        /// 获取数字字符串，不足4位用0补足
        /// </summary>
        /// <param name="number">不大于9999的数字</param>
        /// <returns></returns>
        private string getNumber(int number)
        {
            if (number > 9999) return null;
            return (10000 + number).ToString().Substring(1);
        }