GridView中实现CheckBox的全选 (ajax)

根据一位网友的代码修改了一下
用服务器端的方法：
在页面上放一个gridview控件，配置好数据源，编辑列，添加一个模版列，再编辑模版，放入一个checkbox控件。代码如下：

<body>

<form id="form1" runat="server">
GridView中实现CheckBox的全选 (ajax)

<asp:ScriptManager ID="ScriptManager1" runat="server"/>
GridView中实现CheckBox的全选 (ajax)

<div>

<asp:UpdatePanel ID="UpdatePanel1" runat="server">
GridView中实现CheckBox的全选 (ajax)

<ContentTemplate>
GridView中实现CheckBox的全选 (ajax)

<asp:GridView ID="GridView1" runat="server">
GridView中实现CheckBox的全选 (ajax)

<asp:TemplateField>
GridView中实现CheckBox的全选 (ajax)

<HeaderTemplate>
GridView中实现CheckBox的全选 (ajax)

<asp:CheckBox ID="chkAll" runat="server" OnCheckedChanged="chkAll_CheckedChanged" AutoPostBack="True" />
GridView中实现CheckBox的全选 (ajax)

</HeaderTemplate>
GridView中实现CheckBox的全选 (ajax)

<ItemTemplate>
GridView中实现CheckBox的全选 (ajax)

<asp:CheckBox ID="chkItem" runat="server" />
GridView中实现CheckBox的全选 (ajax)

</ItemTemplate>
GridView中实现CheckBox的全选 (ajax)

</asp:TemplateField>
GridView中实现CheckBox的全选 (ajax)

</Columns>
GridView中实现CheckBox的全选 (ajax)

</asp:GridView>
GridView中实现CheckBox的全选 (ajax)

</ContentTemplate>
GridView中实现CheckBox的全选 (ajax)

</asp:UpdatePanel>
GridView中实现CheckBox的全选 (ajax)

</div>

</form>

</body>

后台cs代码：

using System.Web.UI;
GridView中实现CheckBox的全选 (ajax)

using System.Web.UI.WebControls;
GridView中实现CheckBox的全选 (ajax)

using System.Web.UI.WebControls.WebParts;
GridView中实现CheckBox的全选 (ajax)

using System.Web.UI.HtmlControls;
GridView中实现CheckBox的全选 (ajax)

using System.Data.SqlClient;
GridView中实现CheckBox的全选 (ajax)

public partial class Default3 : System.Web.UI.Page