asp.net 使用FileUpload控件上传并显示图片

在项目中经常会遇到上传图片，在点击保存按钮向数据库提交数据之前，让图片显示在Image控件中，方法如下：

                    <tr>
                        <td width="20%" align="right" class="tablesingletdlable">
                            <asp:Label ID="Label6" runat="server" Text="书图"></asp:Label>
                        </td>
                        <td align="left" width="80%" class="tablesingletdinput" colspan="3">
                            <asp:Image ID="tbtmpPic" runat="server" CssClass="inputc" Height="200px" Width="170px" />
                            <asp:HiddenField ID="allFileSize" runat="server" Value="0" />
                            <div id="msg" runat="server" style="text-align: center">
                                <fieldset>
                                    <legend>图 片 选 择 </legend>请选择图片:<asp:FileUpload ID="FileUpload1" runat="server" />  
                                    <a class="zInputBtn">
                                        <asp:Button ID="btnConfirm" runat="server" Text="添加书籍图片" CssClass="inputButton" OnClick="btnConfirm_Click" />  
                                        </a>
                                </fieldset>
                            </div>
                        </td>
                    </tr>

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    /// <summary>
    /// 图片选择确定
    /// </summary>
    /// <param name="sender"></param>
    /// <param name="e"></param>
    protected void btnConfirm_Click(object sender, EventArgs e)
    {
        if (FileUpload1.HasFile)
        {
            string guid = Guid.NewGuid().ToString();
            string newFileName = folder + "\\" + guid + Path.GetExtension(FileUpload1.FileName);
            url = Page.ResolveUrl("~") + "Admin/BookImages/" + guid + Path.GetExtension(FileUpload1.FileName);
            int totalFileSize = Int32.Parse(allFileSize.Value);
            int fileSize = FileUpload1.PostedFile.ContentLength;
            //此处也可以限制单个文件的大小
            if (totalFileSize + fileSize > 1024 * 1024 * 100)
            {
                Page.ClientScript.RegisterClientScriptBlock(typeof(string), "", @"<script>alert('总上传的文件超过了大小设置  1024 * 1024 ！')</script>");
                return;
            }
            FileUpload1.SaveAs(newFileName);
            ListItem item = new ListItem();
            item.Text = FileUpload1.FileName;
            item.Value = url + "|" + newFileName;
            tbtmpPic.Style["display"] = "";
            tbtmpPic.ImageUrl = url;
            totalFileSize += fileSize;
            allFileSize.Value = totalFileSize.ToString();
        }
    }