Asp.Net图片上传

<div>

                        <asp:FileUpload ID="FileUpload1" runat="server" Height="25px"/>
                        <asp:ImageButton runat="server" ID="btn_Upload" ImageUrl="~/Activity/images/upload.gif"
                            Style="margin-bottom: -8px;" OnClick="btn_Upload_Click" /><br />
                        <asp:Image ID="imgUrl" runat="server" Visible="false" /></div> 

protected void btn_Upload_Click(object sender, ImageClickEventArgs e)
        {
            string path = "/uploadfiles/Activity/";
            string folderPathforsave = Server.MapPath(path);
            if (!Directory.Exists(folderPathforsave))
            {
                Directory.CreateDirectory(folderPathforsave);
            }

            string filename = FileUpload1.FileName;

            if (filename != "")
            {
                filename = filename.Substring(filename.LastIndexOf("."));
                if (filename.ToLower() == ".jpg" || filename.ToLower() == ".bmp" || filename.ToLower() == ".gif")
                {
                    string strpic = string.Format("{0:yyyyMMddHHmmssffff}", DateTime.Now)+filename;
                    fup_Act_Image.SaveAs(folderPathforsave + strpic);
                    path += strpic;
                    imgUrl.Visible = true;
                    imgUrl.ImageUrl = path;
                }
                else
                {
                    MsgBox.MsgBoxShow(this.Page, "支持jpg,bmp,gif等上传文件格式！");
                    return;
                }
            }
        }