如何获得CheckBox选中的数量
<asp:DataList ID="DataList_fit" runat="server" RepeatDirection="Horizontal" Width="100%" >
                                                                                    <ItemTemplate>
                                                                                        <table style="width:110px; border-collapse: collapse;">
                                                                                            <tr>
                                                                                                <td><img src="http://localhost:6771/shoping/shop_admin/product_zsimg/gifts_img/<%# DataBinder.Eval(Container.DataItem,"fitting_img")%>" alt="" style="width:100px; height:100px" /></td>
                                                                                            </tr>
                                                                                            <tr>