后台代码：　
　　　　protected void btnpic_upload_Click(object sender, EventArgs e)

        {

            #region 上传文件

            Boolean fileOk = false;

            if (pic_upload.HasFile)//验证是否包含文件

            {

                //取得文件的扩展名,并转换成小写

                string fileExtension = Path.GetExtension(pic_upload.FileName).ToLower();

                //验证上传文件是否图片格式

                fileOk = IsImage(fileExtension);

                if (fileOk)

                {

                    //对上传文件的大小进行检测，限定文件最大不超过8M

                    if (pic_upload.PostedFile.ContentLength < )

                    {

                        string filepath = "~/Admin/I_Institution/Images/";

                        if (Directory.Exists(Server.MapPath(filepath)) == false)//如果不存在就创建file文件夹

                        {

                            Directory.CreateDirectory(Server.MapPath(filepath));

                        }

                        string virpath = filepath + CreatePasswordHash(pic_upload.FileName, ) + fileExtension;//这是存到服务器上的虚拟路径

                        string mappath = Server.MapPath(virpath);//转换成服务器上的物理路径

                        pic.Visible = true;

                        pic_upload.PostedFile.SaveAs(mappath);//保存图片

                        //显示图片

                        pic.ImageUrl = virpath;

                        lbl_pic.Visible = true;

                        //清空提示

                        lbl_pic.Text = "上传成功";

                    }

                    else

                    {

                        pic.Visible = false;

                        lbl_pic.Visible = true;

                        pic.ImageUrl = "";

                        lbl_pic.Text = "文件大小超出8M！请重新选择！";

                    }

                }

                else

                {

                    lbl_pic.Visible = false;

                    pic.ImageUrl = "";

                    lbl_pic.Text = "要上传的文件类型不对！请重新选择！";

                }

            }

            else

            {

                lbl_pic.Visible = false;

                pic.ImageUrl = "";

                lbl_pic.Text = "请选择要上传的图片！";

            }

            #endregion

        }

       /// <summary>

        /// 验证是否指定的图片格式

        /// </summary>

        /// <param name="str"></param>

        /// <returns></returns>

        public bool IsImage(string str)

        {

            bool isimage = false;

            string thestr = str.ToLower();

            //限定只能上传jpg和gif图片

            string[] allowExtension = { ".jpg", ".gif", ".bmp", ".png" };

            //对上传的文件的类型进行一个个匹对

            for (int i = ; i < allowExtension.Length; i++)

            {

                if (thestr == allowExtension[i])

                {

                    isimage = true;

                    break;

                }

            }

            return isimage;

        }

        /// <summary>

        /// 创建一个指定长度的随机salt值

        /// </summary>

        public string CreateSalt(int saltLenght)

        {

            //生成一个加密的随机数

            RNGCryptoServiceProvider rng = new RNGCryptoServiceProvider();

            byte[] buff = new byte[saltLenght];

            rng.GetBytes(buff);

            //返回一个Base64随机数的字符串

            return Convert.ToBase64String(buff);

        }

        /// <summary>

        /// 返回加密后的字符串

        /// </summary>

        public string CreatePasswordHash(string pwd, int saltLenght)

        {

            string strSalt = CreateSalt(saltLenght);

            //把密码和Salt连起来

            string saltAndPwd = String.Concat(pwd, strSalt);

            //对密码进行哈希

            string hashenPwd = FormsAuthentication.HashPasswordForStoringInConfigFile(saltAndPwd, "sha1");

            //转为小写字符并截取前16个字符串

            hashenPwd = hashenPwd.ToLower().Substring(, );

            //返回哈希后的值

            return hashenPwd;

        }

　拿到上传后的图片路径：　　　　
　　　　　　string IconUrl = this.pic.ImageUrl.Trim();
　　　　　　 model.IconUrl = Path.GetFileName(IconUrl);         //获得已上传　图片控件的ＵＲＬ

 <tr>

                        <td height="" width="30%" align="right">

                            机构图标路径 ：

                        </td>

                        <td height="" width="*" align="left">

                            <asp:Image ID="pic" runat="server" Width="200px" Visible="False" /><br />

                            <asp:FileUpload ID="pic_upload" runat="server" />

                            <asp:Button ID="btnpic_upload" runat="server" Text="图片开始上传" OnClick="btnpic_upload_Click" /><br />

                            <asp:Label ID="lbl_pic" runat="server" Text="" Visible="False"></asp:Label>

                        </td>

                    </tr>