上传和下载附件功能

HTML上传部分 
文件名:<asp:TextBox ID="tbFileName" runat="server" Width="150px"></asp:TextBox>文件(80M以内):
                                <asp:FileUpload ID="FileUpload2" runat="server" />
                                <asp:Button ID="Button1" runat="server" CssClass="buttoncss" Text="上传" OnClick="Button1_Click" />

protected void Button1_Click(object sender, EventArgs e)
        {
            if (FileUpload2.HasFile && ViewState["pid"] != null)
            {
                string path = Server.MapPath("ATT");
                //创建目录
                string pid = ViewState["pid"].ToString();
                if (!Directory.Exists(path + "/" + pid))
                {
                    Directory.CreateDirectory(path + "/" + pid);
                }
                path += "/" + pid;
                string filename = "";
                if (!string.IsNullOrEmpty(tbFileName.Text))
                {
                    string hz = FileUpload2.FileName.Substring(FileUpload2.FileName.IndexOf('.'), FileUpload2.FileName.Length - FileUpload2.FileName.IndexOf('.'));
                    filename = tbFileName.Text.Trim() + hz;
                }
                else
                {
                    string Extension = System.IO.Path.GetExtension(FileUpload2.FileName).ToLower();
                    string FileName = FileUpload2.FileName.Substring(0, FileUpload2.FileName.IndexOf(Extension));
                    FileName += DateTime.Now.ToString("yyyyMMddhhmmss");
                    filename = FileName + Extension;
                }
                try
                {
                    FileUpload2.SaveAs(path + "/" + filename);
                    //保存信息
                    AttachmentModel uam = new AttachmentModel();
                    uam.AttFileName = filename.Substring(0, filename.IndexOf('.'));
                    uam.ProjectId = Convert.ToInt32(pid);
                    uam.AttPath = "ATT/" + pid + "/" + filename;
                    LoginUserInfoModel lum = new LoginUserInfoModel();
                    lum = (LoginUserInfoModel)Session["LoginUserInfoModel"];
                    uam.RecordAccountNoID = lum.LoginUserID;
                    if (IPB.SaveATT(uam))
                    {
                        Page.RegisterClientScriptBlock("TS", "<script>jError('上传成功', { TimeShown: 1000, VerticalPosition: 'center' });;</script>");
                        ShowControl();
                    }
                    else
                    {
                        Page.RegisterClientScriptBlock("TS", "<script>jError('上传失败', { TimeShown: 1000, VerticalPosition: 'center' });;</script>");
                    }

                }
                catch (Exception ex)
                {
                    throw ex;
                }

            }
            else
            {
                Page.RegisterClientScriptBlock("TS", "<script>jError('请选择文件', { TimeShown: 1000, VerticalPosition: 'center' });;</script>");
            }
        }

绑定显示上传成功的附件：

private void BindATT(string pid)
        {
            DataTable dt = IPB.GetATT(pid);
            string html = "";
            if (dt != null && dt.Rows != null && dt.Rows.Count > 0)
            {
                foreach (DataRow dr in dt.Rows)
                {
                    html += "<div style='float:left;margin-top:10px;clear:both;'> <a href='" + GetLink(dr["AttPath"].ToString()) + "' target='_blank' style='color:Blue;'>" + dr["AttFileName"].ToString() + " </a>";

                    html += "<a href="javascript:void(0);" onclick="DelAtt('" + dr["id"].ToString() + "','" + HelpBLL.Encode(pid) + "');" style=' font-size:12px;'>删除</a><br/>";

                    html += "</div>";
                }
            }
            else
            {
                html = "<p style='color:red;'>暂无附件</p>";
            }
            LAttHtml.Text = html;
        }

        /// <summary>
        /// 获取下载URL
        /// </summary>
        /// <param name="url"></param>
        /// <returns></returns>
        public static string GetLink(string url)
        {
            string str = "Download.aspx?FileName=" + HttpUtility.UrlEncode(url) + "";
            return str;
        }

Download.aspx 只有后台代码：

protected void Page_Load(object sender, EventArgs e)
        {
            if (!IsPostBack)
            {
                ResponseFile(HttpUtility.UrlDecode(Request.QueryString["FileName"]));
            }
        }
        public void ResponseFile(string fileName)
        {
            try
            {
                String FullFileName = HttpContext.Current.Server.MapPath(fileName);
                FileInfo DownloadFile = new FileInfo(FullFileName);
                Response.Clear();
                Response.Expires = 0;
                Response.Buffer = true;
                Response.Charset = "utf-8";
                Response.ContentEncoding = System.Text.Encoding.UTF8;
                Response.ContentType = "application/octet-stream";
                Response.AppendHeader("Content-Disposition", "attachment;filename=" + System.Web.HttpUtility.UrlEncode(DownloadFile.FullName, System.Text.Encoding.UTF8));
                Response.AppendHeader("Content-Length", DownloadFile.Length.ToString());
                Response.TransmitFile(DownloadFile.FullName);
                Response.End();
            }
            catch
            {

            }

        }