FileUpload控件的问题..囧.

一个DEMO

前台：

<asp:DataList ID="imageList" runat="server" RepeatColumns="3" Width="200px">

   <ItemTemplate>

      <asp:Image ImageUrl='<%# Eval("Name","~/UpLoad/{0}") %>' ID="image1" runat="server" />

   </ItemTemplate>

</asp:DataList>

<br />

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

<asp:Button ID="btnAdd" Text="upload" runat="server" OnClick="btnAdd_Click" />

后台：

protected void Page_PreRender()

    {

        string upFolder = Server.MapPath("~/UpLoad/");

        DirectoryInfo dir = new DirectoryInfo(upFolder);

        this.imageList.DataSource = dir.GetFiles();

        this.imageList.DataBind();

    }

问题是前台的绑定字段的来源有点迷糊: <%# Eval("Name","~/UpLoad/{0}") %> 这的Name字段是哪来的？后台根本没有给呀? 还是说每个控件默认有这个绑定字段？