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();
}
}