gridview模板列中的按钮如何获取

<ItemTemplate>
<asp:Button ID="Button1" onclick="BtnClick" ...
</ItemTemplate>

<ItemTemplate>
    <asp:Lable ID="lbl1" runat="server" Value='<%# Bind("ID1") %>' /> />
</ItemTemplate>
....


protected void BtnClick(object sender,EventArgs e)
{
for (int i = 0; i < gridview1.Rows.Count; i++)
{
Lable lbl= (Lable )this.gridview.Row[i].FindControl("lbl1")
MessageBox(lbl.Text);
}

}