菜鸟求助。

Question

我有个gridview，里面添加了一个dropdownlist和添加删除按钮。
我每次点击添加按钮，之前gridview里面的dropdownlist里选定的项改成初始值了。
怎么让他选定的状态保存？
我dropdownlist里面的项是自己添加的。
点击按钮是往一个DT里面加一行 再从新绑定GV。

Answer 1

前台代码       
 <asp:GridView ID="GridView1" runat="server" CellPadding="4" ForeColor="#333333" GridLines="None"
            Style="margin-right: 0px" AutoGenerateColumns="False" Width="796px" Height="140px">
            <FooterStyle BackColor="#990000" Font-Bold="True" ForeColor="White" />
            <RowStyle BackColor="#FFFBD6" ForeColor="#333333" Width="100px" />
            <Columns>
                <asp:BoundField DataField="Xuhao" HeaderText="序号" />
                <asp:TemplateField HeaderText="工号">
                    <ItemTemplate>
                        <asp:Label ID="Label2" runat="server" Text='<%# Bind("Gonghao") %>'></asp:Label>
                    </ItemTemplate>
                </asp:TemplateField>
                <asp:TemplateField HeaderText="姓名">
                    <ItemTemplate>
                        <asp:DropDownList ID="DropDownList1" runat="server" OnSelectedIndexChanged="DropDownList1_SelectedIndexChanged"
                            AutoPostBack="True">
                            <asp:ListItem>张三</asp:ListItem>
                            <asp:ListItem>李四</asp:ListItem>
                            <asp:ListItem>王五</asp:ListItem>
                            <asp:ListItem>赵六</asp:ListItem>
                        </asp:DropDownList>
                    </ItemTemplate>
                </asp:TemplateField>
                <asp:TemplateField HeaderText="Email账号">
                    <ItemTemplate>
                        <asp:Label ID="Label7" runat="server" Text='<%# Bind("Email") %>'></asp:Label>
                    </ItemTemplate>
                </asp:TemplateField>
                <asp:TemplateField HeaderText="密码">
                    <ItemTemplate>
                        <asp:Label ID="Label5" runat="server" Text='<%# Bind("Paswd") %>'></asp:Label>
                    </ItemTemplate>
                </asp:TemplateField>
                <asp:TemplateField HeaderText="ISP">
                    <ItemTemplate>
                        <asp:DropDownList ID="DropDownList2" runat="server" AutoPostBack="True" OnSelectedIndexChanged="DropDownList2_SelectedIndexChanged">
                            <asp:ListItem>蟾蜍</asp:ListItem>
                            <asp:ListItem>化蛇</asp:ListItem>
                            <asp:ListItem>玄龟</asp:ListItem>
                            <asp:ListItem>百灵</asp:ListItem>
                        </asp:DropDownList>
                    </ItemTemplate>
                </asp:TemplateField>
                <asp:TemplateField HeaderText="操作">
                    <ItemTemplate>
                        <asp:Button ID="Button3" runat="server" Text="增加" OnClick="Button3_Click" />
                        <asp:Button ID="Button4" runat="server" Text="删除" OnClick="Button4_Click" />
                    </ItemTemplate>
                </asp:TemplateField>
            </Columns>
            <PagerStyle BackColor="#FFCC66" ForeColor="#333333" HorizontalAlign="Center" />
            <EmptyDataTemplate>
                <asp:Button ID="Button1" runat="server" Text="Button" />
                <asp:Button ID="Button2" runat="server" Text="Button" />
            </EmptyDataTemplate>
            <SelectedRowStyle BackColor="#FFCC66" Font-Bold="True" ForeColor="Navy" />
            <HeaderStyle BackColor="#990000" Font-Bold="True" ForeColor="White" />
            <AlternatingRowStyle BackColor="White" />
        </asp:GridView>

Answer 2

后台的。
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            bindSouse();
        }
    }
    /**
     * 数据绑定
     * */
    public void bindSouse()
    {
        DataTable dt = new DataTable();
        dt.Columns.Add(new DataColumn("Xuhao"));
        dt.Columns.Add(new DataColumn("Gonghao"));
        dt.Columns.Add(new DataColumn("Email"));
        dt.Columns.Add(new DataColumn("Paswd"));
            DataRow dr = dt.NewRow();
            dr["Xuhao"] = 1;
            dr["Gonghao"] = 1;
            dr["Email"] = "[email protected]";
            dr["Paswd"] = "5684";
            dt.Rows.Add(dr);
        GridView1.DataSource = dt;
        GridView1.DataBind();
        Session["dt"] = dt;
    }
    /**
     * 增加 删除GridView的行。
     * */
    protected void Button3_Click(object sender, EventArgs e)
    {
        int i = GridView1.Rows.Count;
        DataTable dt = Session["dt"] as DataTable;
        DataRow dr = dt.NewRow();
        dr["Xuhao"] = i;
        dr["Gonghao"] = i;
        dr["Email"] = "[email protected]";
        dr["Paswd"] = "5684";
        dt.Rows.Add(dr);
        GridView1.DataSource = dt;
        GridView1.DataBind();
    }
    protected void Button4_Click(object sender, EventArgs e)
    {
        DataTable dt = Session["dt"] as DataTable;
        int row = ((GridViewRow)((Button)sender).NamingContainer).RowIndex;
        dt.Rows.RemoveAt(row);
        GridView1.DataSource = dt;
        GridView1.DataBind();
    }
    /**
     * 通过选择Dropdownlist的值来修改checkboxlist里面的值。
     * 
     * */
    protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
    {
        int id = ((GridViewRow)(((DropDownList)sender).NamingContainer)).RowIndex;
        bool action = false;
        string aaa = GridView1.Rows[0].Cells[0].Text;                         //绑定模板列不能直接取值。
        string aaaa = GridView1.Rows[0].Cells[1].FindControl("Label2").ToString(); //取值的问题
        Label lable = GridView1.Rows[0].FindControl("Label2") as Label;
        string bb = lable.Text;
        for (int i = 0; i < CheckBoxList1.Items.Count; i++)
        {
            if (GridView1.Rows[id].Cells[0].Text == CheckBoxList1.Items[i].Value)
            {
                action = true;
                break;
            }
        }
        if (!action)
        {
            CheckBoxList1.Items.Add(((DropDownList)sender).SelectedValue);
            CheckBoxList1.Items[CheckBoxList1.Items.Count - 1].Value = GridView1.Rows[id].Cells[0].Text;
        }
        else
        {
            for (int i = 0; i < CheckBoxList1.Items.Count; i++)
            {
                if (CheckBoxList1.Items[i].Value == GridView1.Rows[id].Cells[0].Text)
                {
                    CheckBoxList1.Items[i].Text = ((DropDownList)sender).SelectedValue;
                }
            }
        }
        DropDownList ddl1 = GridView1.Rows[id].Cells[2].FindControl("DropDownList1") as DropDownList;
        ddl1.Items[ddl1.SelectedIndex].Selected=true;
        string sss = ddl1.SelectedValue.ToString();
    }