分页时维护复选框状态时出错

Question

我访问了各个网站并找到了很多答案，但似乎没有一个能解决我的错误。 我想保持复选框的状态，以便在返回第1页之前检查复选框的数量在转到第2页之前保持不变。我的代码如下： Default.aspx文件是：

<%@ Page Title="Home Page" Language="C#" MasterPageFile="~/Site.Master" AutoEventWireup="true"       CodeBehind="Default.aspx.cs" Inherits="DatabaseAndDataSourceControls._Default" %>
<asp:Content ID="BodyContent" ContentPlaceHolderID="MainContent" runat="server">

    <div class="jumbotron">
        <h1>ASP.NET DatabaseAndDataSourceControls Demo<br />
        </h1>
    </div>

<div class="row">
    <div class="col-md-4">


<asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStrings:ConnectionStringNorthwnd %>" SelectCommand="SELECT [CustomerID], [CompanyName], [ContactName], [City], [Country], [Phone] FROM [Customers]" DeleteCommand="DELETE FROM [Customers] WHERE [CustomerID] = @CustomerID" InsertCommand="INSERT INTO [Customers] ([CustomerID], [CompanyName], [ContactName], [City], [Country], [Phone]) VALUES (@CustomerID, @CompanyName, @ContactName, @City, @Country, @Phone)" UpdateCommand="UPDATE [Customers] SET [CompanyName] = @CompanyName, [ContactName] = @ContactName, [City] = @City, [Country] = @Country, [Phone] = @Phone WHERE [CustomerID] = @CustomerID">
                <DeleteParameters>
                <asp:Parameter Name="CustomerID" Type="String" />


</DeleteParameters>
            <InsertParameters>
                <asp:Parameter Name="CustomerID" Type="String" />
                <asp:Parameter Name="CompanyName" Type="String" />
                <asp:Parameter Name="ContactName" Type="String" />
                <asp:Parameter Name="City" Type="String" />
                <asp:Parameter Name="Country" Type="String" />
                <asp:Parameter Name="Phone" Type="String" />
            </InsertParameters>
            <UpdateParameters>
                <asp:Parameter Name="CompanyName" Type="String" />
                <asp:Parameter Name="ContactName" Type="String" />
                <asp:Parameter Name="City" Type="String" />
                <asp:Parameter Name="Country" Type="String" />
                <asp:Parameter Name="Phone" Type="String" />
                <asp:Parameter Name="CustomerID" Type="String" />
            </UpdateParameters>
        </asp:SqlDataSource>
        <asp:SqlDataSource ID="SqlDataSource2" runat="server" ConnectionString="<%$ ConnectionStrings:ConnectionStringNorthwnd %>" DeleteCommand="DELETE FROM [Customers] WHERE [CustomerID] = @CustomerID" InsertCommand="INSERT INTO [Customers] ([CustomerID], [CompanyName], [ContactName], [ContactTitle], [Address], [City], [Region], [PostalCode], [Country], [Phone], [Fax]) VALUES (@CustomerID, @CompanyName, @ContactName, @ContactTitle, @Address, @City, @Region, @PostalCode, @Country, @Phone, @Fax)" SelectCommand="SELECT * FROM [Customers] WHERE ([CustomerID] = @CustomerID)" UpdateCommand="UPDATE [Customers] SET [CompanyName] = @CompanyName, [ContactName] = @ContactName, [ContactTitle] = @ContactTitle, [Address] = @Address, [City] = @City, [Region] = @Region, [PostalCode] = @PostalCode, [Country] = @Country, [Phone] = @Phone, [Fax] = @Fax WHERE [CustomerID] = @CustomerID">
            <DeleteParameters>
                <asp:Parameter Name="CustomerID" Type="String" />
            </DeleteParameters>
            <InsertParameters>
                <asp:Parameter Name="CustomerID" Type="String" />
                <asp:Parameter Name="CompanyName" Type="String" />
                <asp:Parameter Name="ContactName" Type="String" />
                <asp:Parameter Name="ContactTitle" Type="String" />
                <asp:Parameter Name="Address" Type="String" />
                <asp:Parameter Name="City" Type="String" />
                <asp:Parameter Name="Region" Type="String" />
                <asp:Parameter Name="PostalCode" Type="String" />
                <asp:Parameter Name="Country" Type="String" />
                <asp:Parameter Name="Phone" Type="String" />
                <asp:Parameter Name="Fax" Type="String" />
            </InsertParameters>
            <SelectParameters>
                <asp:ControlParameter ControlID="GridView1" Name="CustomerID" PropertyName="SelectedValue" Type="String" />
            </SelectParameters>
            <UpdateParameters>
                <asp:Parameter Name="CompanyName" Type="String" />
                <asp:Parameter Name="ContactName" Type="String" />
                <asp:Parameter Name="ContactTitle" Type="String" />
                <asp:Parameter Name="Address" Type="String" />
                <asp:Parameter Name="City" Type="String" />
                <asp:Parameter Name="Region" Type="String" />
                <asp:Parameter Name="PostalCode" Type="String" />
                <asp:Parameter Name="Country" Type="String" />
                <asp:Parameter Name="Phone" Type="String" />
                <asp:Parameter Name="Fax" Type="String" />
                <asp:Parameter Name="CustomerID" Type="String" />
            </UpdateParameters>
        </asp:SqlDataSource>
        <h2>Manage Customers&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
            <asp:Label ID="Label1" runat="server"></asp:Label>
        &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
            <asp:Button ID="Save" runat="server" Font-Size="Medium" Height="25px" Text="Save" Width="80px" OnClick="Save_Click" />
        &nbsp;&nbsp;&nbsp;
            <asp:Button ID="Check" runat="server" Font-Size="Medium" Height="25px" Text="Check" Width="80px" OnClick="Check_Click" />
        </h2>
        <asp:GridView ID="GridView1" runat="server" AllowPaging="True" AllowSorting="True" AutoGenerateColumns="False" CellPadding="4" DataKeyNames="CustomerID" DataSourceID="SqlDataSource1" ForeColor="#333333" GridLines="None" OnRowCommand="GridView1_RowCommand" OnPageIndexChanging="GridView1_PageIndexChanging">
            <AlternatingRowStyle BackColor="White" ForeColor="#284775" />
            <Columns>
                <asp:TemplateField HeaderText="CheckBox">
                    <ItemTemplate>
                        <asp:CheckBox ID="EmpSelector" runat="server" Text="EmpSelector"/>
                    </ItemTemplate>
                </asp:TemplateField>
                <asp:CommandField ShowEditButton="True" ShowSelectButton="True" />
                <asp:BoundField DataField="CustomerID" HeaderText="CustomerID" ReadOnly="True" SortExpression="CustomerID" />
                <asp:BoundField DataField="CompanyName" HeaderText="CompanyName" SortExpression="CompanyName" />
                <asp:BoundField DataField="ContactName" HeaderText="ContactName" SortExpression="ContactName" />
                <asp:BoundField DataField="City" HeaderText="City" SortExpression="City" />
                <asp:BoundField DataField="Country" HeaderText="Country" SortExpression="Country" />
                <asp:BoundField DataField="Phone" HeaderText="Phone" SortExpression="Phone" />
                <asp:TemplateField HeaderText="View Details">
                    <ItemTemplate>
                        <asp:Button ID="Button1" runat="server" CausesValidation="False" CommandArgument= '<%# Eval("CustomerID") %>' CommandName="ViewDetails" Text="View Details" />
                    </ItemTemplate>
                </asp:TemplateField>
            </Columns>
            <EditRowStyle BackColor="#999999" />
            <FooterStyle BackColor="#5D7B9D" Font-Bold="True" ForeColor="White" />
            <HeaderStyle BackColor="#5D7B9D" Font-Bold="True" ForeColor="White" />
            <PagerStyle BackColor="#284775" ForeColor="White" HorizontalAlign="Center" />
            <RowStyle BackColor="#F7F6F3" ForeColor="#333333" />
            <SelectedRowStyle BackColor="#E2DED6" Font-Bold="True" ForeColor="#333333" />
            <SortedAscendingCellStyle BackColor="#E9E7E2" />
            <SortedAscendingHeaderStyle BackColor="#506C8C" />
            <SortedDescendingCellStyle BackColor="#FFFDF8" />
            <SortedDescendingHeaderStyle BackColor="#6F8DAE" />
        </asp:GridView>
        <asp:DetailsView ID="DetailsView1" runat="server" AutoGenerateRows="False" BackColor="White" BorderColor="#DEDFDE" BorderStyle="None" BorderWidth="1px" CellPadding="4" DataKeyNames="CustomerID" DataSourceID="SqlDataSource2" ForeColor="Black" GridLines="Vertical" HeaderText="Customer Details" Height="50px" Width="125px">
            <AlternatingRowStyle BackColor="White" />
            <EditRowStyle BackColor="#CE5D5A" Font-Bold="True" ForeColor="White" />
            <Fields>
                <asp:BoundField DataField="CustomerID" HeaderText="CustomerID" ReadOnly="True" SortExpression="CustomerID" />
                <asp:BoundField DataField="CompanyName" HeaderText="CompanyName" SortExpression="CompanyName" />
                <asp:BoundField DataField="ContactName" HeaderText="ContactName" SortExpression="ContactName" />
                <asp:BoundField DataField="ContactTitle" HeaderText="ContactTitle" SortExpression="ContactTitle" />
                <asp:BoundField DataField="Address" HeaderText="Address" SortExpression="Address" />
                <asp:BoundField DataField="City" HeaderText="City" SortExpression="City" />
                <asp:BoundField DataField="Region" HeaderText="Region" SortExpression="Region" />
                <asp:BoundField DataField="PostalCode" HeaderText="PostalCode" SortExpression="PostalCode" />
                <asp:BoundField DataField="Country" HeaderText="Country" SortExpression="Country" />
                <asp:BoundField DataField="Phone" HeaderText="Phone" SortExpression="Phone" />
                <asp:BoundField DataField="Fax" HeaderText="Fax" SortExpression="Fax" />
                <asp:CommandField ShowEditButton="True" ShowInsertButton="True" />
            </Fields>
            <FooterStyle BackColor="#CCCC99" />
            <FooterTemplate>
                No customer is currently selected.<br />
                <asp:LinkButton ID="LinkButton1" runat="server" CausesValidation="False" CommandName="New">New</asp:LinkButton>
            </FooterTemplate>
            <HeaderStyle BackColor="#6B696B" Font-Bold="True" ForeColor="White" />
            <PagerStyle BackColor="#F7F7DE" ForeColor="Black" HorizontalAlign="Right" />
            <RowStyle BackColor="#F7F7DE" />
        </asp:DetailsView>
        <br />
    </div>
</div>

</asp:Content>

CS文件是：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Collections;

namespace DatabaseAndDataSourceControls
{
    public partial class _Default : Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {

        }

        protected void DetailsView1_ItemUpdated(object sender, DetailsViewUpdatedEventArgs e)
        {
            GridView1.DataBind();
        }
        protected void DetailsView1_ItemInserted(object sender,
        DetailsViewInsertedEventArgs e)
        {
            GridView1.DataBind();
        }

        protected void Button1_Click(object sender, EventArgs e)
        {
        }
        protected void GridView1_RowCommand(object sender, GridViewCommandEventArgs e)
        {       
        }

        protected void GridView1_PageIndexChanging(object sender, GridViewPageEventArgs e)
        {
            savechkdvls();

            GridView1.PageIndex = e.NewPageIndex;

            chkdvaluesp();

            GridView1.DataBind();



        }

        private void chkdvaluesp()
        {

            ArrayList usercontent = (ArrayList)Session["chkditems"];

            //String index = "";

            if (usercontent != null && usercontent.Count > 0)
            {

                foreach (GridViewRow gvrow in GridView1.Rows)
                {

                    String index = (GridView1.DataKeys[gvrow.RowIndex].Value).ToString();

                    if (usercontent.Contains(index))
                    {

                        CheckBox myCheckBox = (CheckBox)gvrow.FindControl("EmpSelector");

                        myCheckBox.Checked = true;
                        Label1.Text += index + " is checked </br></br>";

                    }

                }

            }

        }

        /////////////////////////
        private void savechkdvls()
        {

            ArrayList usercontent = new ArrayList();

            String index1 = "";

            foreach (GridViewRow gvrow in GridView1.Rows)
            {

                index1 = (GridView1.DataKeys[gvrow.RowIndex].Value).ToString();

                bool result = ((CheckBox)gvrow.FindControl("EmpSelector")).Checked;


                // Check in the Session

                if (Session["chkditems"] != null)

                    usercontent = (ArrayList)Session["chkditems"];

                if (result)
                {

                    if (!usercontent.Contains(index1))

                        usercontent.Add(index1);

                }

                else

                    usercontent.Remove(index1);

            }

            if (usercontent != null && usercontent.Count > 0)

                Session["chkditems"] = usercontent;

        }

        protected void Save_Click(object sender, EventArgs e)
        {
            savechkdvls();

        }

        protected void Check_Click(object sender, EventArgs e)
        {
            chkdvaluesp();
        }
    }
    }

我添加了两个按钮Save and Check。因此，当我将页面从2移动到1后单击它们。复选框会更新。但是没有Save_click和Check_Click事件，复选框不会更新。请帮忙。