string imgpath = "";
        Random ran = new Random();
        if (FileUpload1.HasFile)
        {
            string fileContentType = FileUpload1.PostedFile.ContentType;
            if (fileContentType == "image/bmp" || fileContentType == "image/gif" || fileContentType == "image/pjpeg")
            {
                string name = FileUpload1.PostedFile.FileName;                  // 客户端文件路径

                DateTime time = DateTime.Now;
                string newfilename = time.Year.ToString() + time.Month + time.Day + time.Hour.ToString() + time.Millisecond.ToString() + ran.Next(1000, 9999).ToString() + time.Second.ToString() + time.Millisecond.ToString() + ran.Next(1000, 9999).ToString();
                FileInfo file = new FileInfo(name);
                string fileName = file.Name;                                    // 文件名称
                string extension = Path.GetExtension(file.Extension);
                fileName = newfilename + extension;
                imgpath = "uploadfile/" + fileName;
                string webFilePath = Server.MapPath("../uploadfile/" + fileName);        // 服务器端文件路径
                if (!File.Exists(webFilePath))
                {
                    try
                    {
                        FileUpload1.SaveAs(webFilePath);                                // 使用     
                    }
                    catch (Exception ex)
                    {
                        Alert.ShowOnly("Tip: file upload fails, the reason for failure：" + ex.Message);
                    }
                }
                else
                {
                    Alert.ShowOnly("Tip: file already exists. Please rename after uploading");
                }
            }
            else
            {
                Alert.ShowOnly("Tip: file types");
            }
            this.SmallPic.Value = imgpath;
        }