朱金灿       前言：最近使用asp.net做开发，有了一些心得，特写出来，望能起一个抛砖引玉的作用。       在DataGrid 的模板列中加入CheckBox ,如果对DataGrid设置分页，前一页已经选中的CheckBox在回到原页时，CheckBox的状态会变为初始状态。        如果想保存checkbox的状态，则可以用Session保存。我从网上下载了一篇文章是这样做的：       1、首先，建立DataGrid.          <asp:datagrid id="DataGrid1" style="Z-INDEX: 101; LEFT: 12px; POSITION: absolute; TOP: 88px" runat="server" AllowPaging="True" Width="416px" Height="248px">                 <AlternatingItemStyle BackColor="#EEEEEE"></AlternatingItemStyle>                 <ItemStyle Font-Size="12px" Font-Names="宋体"></ItemStyle>                 <HeaderStyle Font-Size="12px" Font-Names="宋体" BackColor="#00CCFF"></HeaderStyle>                 <FooterStyle HorizontalAlign="Center"></FooterStyle>                 <Columns>                     <asp:TemplateColumn>                         <ItemTemplate>                             <asp:checkbox id="CheckBox1" runat="server"></asp:checkbox>                         </ItemTemplate>                     </asp:TemplateColumn>                 </Columns>             </asp:datagrid>                2、在Global.asax文件中，Session_Start事件中建立Session Sub Session_Start(ByVal sender As Object, ByVal e As EventArgs)                ' 在会话启动时激发            Dim checks As Boolean() = New Boolean(10000) {}            Dim i As Integer            For i = 0 To 10000                checks(i) = False            Next           Session.Add("CheckBoxchecks", checks)        End Sub 3.在DataGrid的PageIndexChanged事件中：  Private Sub DataGrid1_PageIndexChanged(ByVal source As Object, ByVal e As System.Web.UI.WebControls.DataGridPageChangedEventArgs) Handles DataGrid1.PageIndexChanged         Dim count As Integer         Dim cnn As OleDb.OleDbConnection = New OleDb.OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=c:\UserLog.mdb")         Dim da As New OleDb.OleDbDataAdapter("select * from mm", cnn)         da.Fill(dst)         count = dst.Tables(0).Rows.Count   'DataGrid中的记录总数；         Dim check As Boolean()         check = Me.Session("checkboxchecks")  'check()是记录checkbox状态的数组，用session保存。  Dim j As Integer  For j = 0 To DataGrid1.PageSize - 1  Dim Che As CheckBox = DataGrid1.Items(j).Cells(0).FindControl("CheckBox1")  If Not Che Is Nothing Then  If Che.Checked = True Then  check(DataGrid1.CurrentPageIndex * DataGrid1.PageSize + j) = True   Else     check(DataGrid1.CurrentPageIndex * DataGrid1.PageSize + j) = False                     End If                 End If             Next         DataGrid1.CurrentPageIndex = e.NewPageIndex         Dim ds As New DataSet()         da.Fill(ds, "a")         DataGrid1.DataSource = ds         DataGrid1.DataBind()             Dim i As Integer             For i = 0 To DataGrid1.PageSize - 1                 Dim Cx2 As CheckBox = DataGrid1.Items(i).Cells(0).FindControl("CheckBox1")                 If check(DataGrid1.CurrentPageIndex * DataGrid1.PageSize + i) = True Then                     Cx2.Checked = True                 Else                     Cx2.Checked = False                 End If             Next          End Sub 这样就可以利用Session实现checkbox翻页后的状态保存问题. 作者Blog：http://blog.csdn.net/guoyan19811021/     实际上我对该文的看法是提供了一个好思路，但是具体实现无疑显得拙劣了一点，具体表现在：一.文中首先定义了一个有一万个元素的数组用来保存checkbox的状态， Dim checks As Boolean() = New Boolean(10000) {}，这样一来当记录数大于10000时显然是不够用的，而小于10000条时又浪费了；二是文中程序对选中和未选中都进行记录，这有点多余，其实我们只要记录选中的id号就行了。鉴于此，我和同事对此进行了一点改进（这里采用C#实现）。 1、首先，建立DataGrid，其中checkbox的id为ChkSelected。         <asp:datagrid id="DataList" runat="server" Width="542px" PageSize="4" DataKeyField="book_id" AutoGenerateColumns="False"BorderStyle="None" CellPadding="3" BorderWidth="1px" BackColor="White" BorderColor="#E6E7E8"Height="0px" AllowPaging="True" Font-Size="12px" Font-Names="Arial"><SelectedItemStyle Font-Bold="True" ForeColor="#663399" BackColor="#FFCC66"></SelectedItemStyle> <AlternatingItemStyle HorizontalAlign="Center" ForeColor="Black" BackColor="#EBF8FE"></AlternatingItemStyle> <ItemStyle HorizontalAlign="Center" ForeColor="Black" BackColor="White"></ItemStyle> <HeaderStyle Font-Size="12px" Font-Names="Arial" Font-Bold="True" HorizontalAlign="Center" ForeColor="White"BackColor="#FF9900"></HeaderStyle><FooterStyle ForeColor="#330099" BackColor="#FFFFCC"></FooterStyle><Columns> <asp:BoundColumn DataField="book_name" HeaderText="介质名称"></asp:BoundColumn> <asp:BoundColumn DataField="book_keyword" HeaderText="关键词"></asp:BoundColumn><asp:BoundColumn DataField="book_depoisit" HeaderText="保存位置"></asp:BoundColumn><asp:BoundColumn DataField="book_inlibdate" HeaderText="入库时间" DataFormatString="{0:yyyy-M-d }"></asp:BoundColumn><asp:BoundColumn DataField="fieldvalue" HeaderText="处理状态"></asp:BoundColumn><asp:TemplateColumn HeaderText="是否选中"><HeaderTemplate><FONT face="宋体"></FONT></HeaderTemplate><ItemTemplate><FONT face="宋体">&nbsp;</FONT><asp:CheckBox ID="ChkSelected" runat="server" Text="" Checked="False"></asp:CheckBox></ItemTemplate></asp:TemplateColumn></Columns><PagerStyle Font-Size="12px" Font-Names="Arial" HorizontalAlign="Left" ForeColor="Blue" BackColor="White"                                                                                 Mode="NumericPages"></PagerStyle> </asp:datagrid></FONT></P> 2. 新建一个私有函数用于保存当前选择的数据项 private void SaveSelecedSession(){   // 从session中取出ArrayList ArrayList al = (ArrayList)this.Session["BookManage_CheckBoxchecks"]; // 假如ArrayList不存在，就新建一个 if (al == null) al = new ArrayList();    for(int n = 0;n<DataList.Items.Count;n++)     { CheckBox cb = (CheckBox)DataList.Items[n].Cells[3].FindControl("ChkSelected"); if(cb!=null){  // 取出记录的id号 string id = DataList.DataKeys[DataList.Items[n].ItemIndex].ToString();  // 判断id是否存在ArrayList中 bool con =al.Contains(id); if (cb.Checked){  // 假如被选中同时又不存在ArrayList中，将id号加进ArrayList. if (!con)         al.Add(id);     } else                     {   //假如被选中同时又存在ArrayList中，将该id号从ArrayList中删除，此举用于确保//ArrayList中的id号是唯一的。                         if (con)                         {                             al.Remove(id);                         }                       }                 }             }               //保存结果到Session中             this.Session["BookManage_CheckBoxchecks"] = al;         }   3.在DataGrid的PageIndexChanged事件响应函数中调用SaveSelectedSession函数，具体如下：         private void DataList_PageIndexChanged(object source, System.Web.UI.WebControls.DataGridPageChangedEventArgs e)         {//保存当前选择的数据项             SaveSelecedSession();             //邦定数据表             DataList.CurrentPageIndex = e.NewPageIndex;             string ExecuteSql = "select a.book_id,a.book_name,a.book_keyword,a.book_depoisit,a.book_inlibdate,b.fieldvalue from intel.cs_bookinfo a,intel.cs_dictionary b where a.book_status!=4 and a.book_status=b.fieldid and b.tablename='CS_BookInfo' and b.fieldname = 'Book_Status'";             RefreshData(ExecuteSql); ArrayList al = (ArrayList)this.Session["BookManage_CheckBoxchecks"];             if (al == null)                 al = new ArrayList();     //根据原来保存的选择项id号对checkbox进行初始化             for(int n = 0;n<DataList.Items.Count;n++)             {                 CheckBox cb = (CheckBox)DataList.Items[n].Cells[3].FindControl("ChkSelected");         if(cb!=null)                 {                     string id  = DataList.DataKeys[DataList.Items[n].ItemIndex].ToString();                     bool con =al.Contains(id);                     if (!con)                         cb.Checked = false;                     else                         cb.Checked = true;                 }             }           } 这样做，就可以克服上文的程序的缺点：应对不确定的记录数（因为ArrayList是动态增加的），同时又只保存了选择中记录的id号。  

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