protected void btnOK_Click(object sender, EventArgs e)
    {
        //上传列表图片
        try
        {
            string datedir = DateTime.Now.ToString("yyyyMMdd");
            string name = Maticsoft.Utility.Tool.Upload(myFileUpload, new string[] { ".jpg", ".png", ".gif" }, 3, Server.MapPath("../download/"));
            
        }
        catch (Exception ex)
        {
            //错误        }
    }

------解决方案--------------------

傻了。竟然忘记贴函数了。SORRY
C# code

    public static string Upload(FileUpload myFileUpload, string[] allowExtensions, int maxLength, string savePath)
        {
            // 文件格式是否允许上传
            bool fileAllow = false;

            //检查是否有文件案
            if (myFileUpload.HasFile)
            {
                // 检查文件大小, ContentLength获取的是字节，转成M的时候要除以2次1024
                if (myFileUpload.PostedFile.ContentLength / 1024 / 1024 >= maxLength)
                {
                    throw new Exception("只能上传小于" + maxLength + "M的文件！");
                }

                //取得上传文件之扩展文件名，并转换成小写字母
                string fileExtension = System.IO.Path.GetExtension(myFileUpload.FileName).ToLower();
                string tmp = "";   // 存储允许上传的文件后缀名
                //检查扩展文件名是否符合限定类型
                for (int i = 0; i < allowExtensions.Length; i++)
                {
                    tmp += i == allowExtensions.Length - 1 ? allowExtensions[i] : allowExtensions[i] + ",";
                    if (fileExtension == allowExtensions[i])
                    {
                        fileAllow = true;
                    }
                }

                if (fileAllow)
                {
                    try
                    {
                        string datedir = DateTime.Now.ToString("yyyyMMdd");
                        if (!Directory.Exists(savePath + datedir))
                        {
                            Directory.CreateDirectory(savePath + datedir);
                        }
                        string saveName = Guid.NewGuid() + fileExtension;
                        string path = savePath + datedir + "/" + saveName;
                        //存储文件到文件夹
                        myFileUpload.SaveAs(path);
                        return datedir + "/" + saveName;
                    }
                    catch (Exception ex)
                    {
                        throw new Exception(ex.Message);
                    }
                }
                else
                {
                    throw new Exception("文件格式不符，可以上传的文件格式为：" + tmp);
                }
            }
            else
            {
                throw new Exception("请选择要上传的文件！");
            }
        }

------解决方案--------------------
 protected void UploadButton_Click(object sender, EventArgs e)  
   {  
       string uploadName = InputFile.Value;//获取待上传图片的完整路径，包括文件名  
       //string uploadName = InputFile.PostedFile.FileName;  
       string pictureName = "";//上传后的图片名，以当前时间为文件名，确保文件名没有重复  
       if (InputFile.Value != "")  
       {  
           int idx = uploadName.LastIndexOf(".");  
           string suffix = uploadName.Substring(idx);//获得上传的图片的后缀名  
           pictureName = DateTime.Now.Ticks.ToString() + suffix;  
       }  
       try  
       {  
           if (uploadName != "")