如何获取repeater某行第一列的值

<div>
    <asp:Repeater ID="Repeater1" runat="server" DataMember="DefaultView" 
            DataSourceID="SqlDataSource1">
            <ItemTemplate>
                <asp:Label ID="Label1" runat="server" Text=<%# Eval("ProductID")%>></asp:Label>
                <asp:Label ID="Label2" runat="server" Text=<%# Eval("ProductName")%>></asp:Label>
                <br />          

            </ItemTemplate>
    </asp:Repeater>
        <asp:SqlDataSource ID="SqlDataSource1" runat="server" 
            ConnectionString="<%$ ConnectionStrings:NorthwindConnectionString %>" 
            SelectCommand="SELECT [ProductID], [ProductName] FROM [Products]">
        </asp:SqlDataSource>
        <br />
        <asp:Button ID="Button1" runat="server" onclick="Button1_Click" Text="Button" />
    </div>

 protected void Button1_Click(object sender, EventArgs e)
        {
            Label textControl = (Label)Repeater1.Items[3].FindControl("Label1");
            //textControl.Text 就是你需要的值
        }

foreach (RepeaterItem rs in Repeater1.Items)
        {
            string str = ((Label)rs.FindControl("控件ID")).Text;
        }