.net开发中批量删除记录时实现全选功能的具体方法

<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False" DataKeyNames="ProductID"
    DataSourceID="SqlDataSource1">
    <Columns>
        <asp:BoundField DataField="ProductID" HeaderText="ProductID" InsertVisible="False"
            ReadOnly="True" SortExpression="ProductID" />
        <asp:BoundField DataField="ProductName" HeaderText="ProductName" SortExpression="ProductName" />
        <asp:BoundField DataField="SupplierID" HeaderText="SupplierID" SortExpression="SupplierID" />
        <asp:BoundField DataField="CategoryID" HeaderText="CategoryID" SortExpression="CategoryID" />
        <asp:TemplateField>
            <ItemTemplate>
                <asp:CheckBox ID="chk_Del" runat="server" />
            </ItemTemplate>
        </asp:TemplateField>
    </Columns>
</asp:GridView>

//接下来往页面上添加一个checkbox控件

<asp:CheckBox ID="chk_JS" runat="server" Text="全选(JS)" onclick="selectAll(this)"/>
//并为该控件编写JS脚本如下：
<script type="text/javascript">

    //根据传入的checkbox的选中状态设置所有checkbox的选中状态
    function selectAll(obj)
    {
        var allInput = document.getElementsByTagName("input");
        //alert(allInput.length);
        var loopTime = allInput.length;
        for(i = 0;i < loopTime;i++)
        {
            //alert(allInput[i].type);
            if(allInput[i].type == "checkbox")
            {
                allInput[i].checked = obj.checked;
            }
        }
    }
</script>
//基本效果就有了，接下来我们在点缀一下。在网页中添加一个button
<asp:Button ID="btn_DeleteRecords" runat="server" OnClientClick="return judgeSelect();" Text="删除选中记录" />
//添加JS脚本
//判断是否选中记录，用户确认删除
function judgeSelect()
{
    var result = false;
    var allInput = document.getElementsByTagName("input");
    var loopTime = allInput.length;
    for(i = 0;i < loopTime;i++)
    {
        if(allInput[i].checked)
        {
            result = true;
            break;
        }
    }
    if(!result)
    {
        alert("请先选则要删除的记录！");
        return result;
    }
    result = confirm("你确认要删除选定的记录吗？");
    return result;
}

int a = this.GridView1.Rows.Count;
for (int i = 0; i < a; i++)
{
    CheckBox chk = (CheckBox)this.GridView1.Rows[i].FindControl("chk_Del");
    chk.Checked = this.chk_Server.Checked;
}