<div>
            <asp:ScriptManager ID="ScriptManager1" runat="server">
            </asp:ScriptManager>
            <asp:UpdatePanel ID="UpdatePanel1" runat="server">
            <ContentTemplate>
            <table>
                <tr><td>
                    <asp:FileUpload ID="FileUpload1" runat="server"></asp:FileUpload>
                </td></tr>
            </table>
            </ContentTemplate>
                <Triggers>
                    <asp:PostBackTrigger ControlID="UploadButton" />
                </Triggers>
            </asp:UpdatePanel>
            <table>
                <tr><td>
                    <asp:Button ID="UploadButton" Text="导入" OnClick="UploadButton_Click" runat="server"></asp:Button>
                    <asp:Button ID="btnReturn" runat="server" Text="关闭" OnClientClick ="CloseDiv();"/>
                </td></tr>
            </table>
        </div>我的前台代码如上,点击“UploadButton”后仍然无法找到上传文件,请大家帮忙。