获取不到Repeater控件中的CheckBox选中状态

写在前面的话：在做一个项目的时候，需要使用到Repeater控件，并且在Repeater控件内放置了CheckBox控件来标志需要删除的行，选中后，在后台取到的CheckBox的值总是为false。最后发现是在PageLoad函数中没有判断是否是回发就绑定了Repeater控件的数据，那么每次进入页面CheckBox控件的值当然被刷新为false了。

前台页面：

<div class="contianer p10">
        <h3>
            当前位置：<a href="Index.aspx" target="_self" >首页</a>>文章管理</h3>
        <hr/>
        <div class="content">         
                <asp:repeater ID="rptArticle" runat="server" ClientIDMode="Static" >
                <HeaderTemplate>
                <table border="0" cellspacing="0" cellpadding="0" width="100%">
                    <tr>
                        <th width="6%">选择</th>
                        <th width="6%">编号</th>
                        <th align="left">文章标题</th>
                        <th width="16%">发布时间</th>
                        <th width="10%">操作</th>
                    </tr>
                    </HeaderTemplate>
                    <ItemTemplate>
                        <tr>
                            <td><asp:CheckBox ID="cb_id" CssClass="checkall" runat="server" /></td>
                            <td><asp:Label ID="lb_id" runat="server" Text='<%#Eval("aNo")%>'></asp:Label></td>
                            <td><a href="ArticleShow.aspx?id=<%#Eval("aNo") %>"><%#Eval("aTitle")%></a></td>
                            <td><%#string.Format("{0:g}", Eval("aDate"))%></td>
                            <td><span><a href="ArticleShow.aspx?id=<%#Eval("aNo") %>">修改</a></span></td>
                        </tr>
                    </ItemTemplate>
                    <FooterTemplate>
                    </table>
                    </FooterTemplate>
                </asp:repeater>
        </div>
        <div class="clear"></div>
          <!-- 分页控件 -->
          <div>
            <webdiyer:AspNetPager ID="AspNetPager1" runat="server" HorizontalAlign="Right" ShowCustomInfoSection="Right"
                Width="100%" Style="font-size: 12px" inputboxstyle="width:19px" CustomInfoHTML=""
                ShowPageIndexBox="Always" AlwaysShow="false" FirstPageText="首页" LastPageText="尾页"
                NextPageText="下一页" PrevPageText="上一页" CustomInfoStyle="FONT-SIZE: 12px" CurrentPageButtonClass="pagination"
                PageSize="16" ForeColor="#1460AD" OnPageChanged="AspNetPager1_PageChanged">
            </webdiyer:AspNetPager>
          </div>
          <!-- 分页控件end -->

        <br />
        <asp:Button ID="BtnDelete" runat="server" 
        OnClientClick="return confirm( '确定要删除这些记录吗？ ');" 
        onclick="BtnDelete_Click" Text="删除" />
    &nbsp;
        <asp:Label ID="lbMsg" runat="server" Text=""></asp:Label>
        &nbsp;
        <asp:Button ID="BtnAdd" runat="server" Text="添加" 
            onclick="BtnAdd_Click"/>

    </div>

后台页面：

ArticleBLL bll = new ArticleBLL();
        protected void Page_Load(object sender, EventArgs e)
        {
            this.lbMsg.Text = "";
            if (!IsPostBack)
            {
                BindRepeater();
            }
        }
        // 绑定数据
        private void BindRepeater()
        {
            string strSql = "select * from article";

            PagedDataSource ps = new PagedDataSource();
            ps.DataSource = bll.GetDataList(strSql).DefaultView;
            AspNetPager1.RecordCount = ps.Count;
            ps.CurrentPageIndex = AspNetPager1.CurrentPageIndex - 1;
            ps.AllowPaging = true;
            ps.PageSize = AspNetPager1.PageSize;
            this.rptArticle.DataSource = ps;
            this.rptArticle.DataBind();
        }
        // 分页控件事件绑定
        public void AspNetPager1_PageChanged(object sender, EventArgs e)
        {
            BindRepeater();
        }
        // 添加文章
        protected void BtnAdd_Click(object sender, EventArgs e)
        {
            Response.Redirect("ArticleShow.aspx");
        }
        // 删除
        protected void BtnDelete_Click(object sender, EventArgs e)
        {
            for (int i = 0; i < rptArticle.Items.Count; i++)
            {
                int id = Convert.ToInt32(((Label)rptArticle.Items[i].FindControl("lb_id")).Text);
                CheckBox cb = (CheckBox)rptArticle.Items[i].FindControl("cb_id");
                if (cb.Checked)
                {
                    bll.Delete(id.ToString());
                }
            }
            this.lbMsg.Text = "删除成功";
        }

处理办法是在PageLoad里面判断是否是回发就可以了。