细说ASP.NET 3.5 中 ListView的ItemCreated和ItemDataBound事件

     ListView是ASP.NET 3.5 Framework中给出的又一个新控件，比起ASP.NET 2.0 Framework的GridView来，又方便了不少。

     在这里，我对自己开发过程中使用ListView控件的一些心得讲述一下。

     ListView的诸事件中的ItemCreated事件和ItemDataBound事件有如下区别:

1.ItemCreated事件发生在ItemDataBound事件之前

2.ItemCreated事件所做的工作是初始化各个模板Template中的控件。

3.ItemDataBound事件在ItemCreated初始化控件后再对需要进行数据绑定的控件进行绑定。

4.要动态的为ListView添加控件，必须在ItemCreated事件期间进行。

5.要去的ListView动态控件的绑定值，必须在ItemDataBound事件期间进行。

例子：

     用ListView列出所有的用户和所有的权限。权限用CheckBoxList来表示。点击相应的权限就做出修改。

前台代码：（控件）

<%@ Control Language="C#" AutoEventWireup="true" CodeBehind="RolesManage.ascx.cs" Inherits="Web.control.RolesManage" %>
<asp:ListView ID="ListView1" runat="server" DataKeyNames="ProviderUserKey" 
    DataSourceID="ODS" 
    onpagepropertieschanged="ListView1_PagePropertiesChanged" 
    onpagepropertieschanging="ListView1_PagePropertiesChanging" 
    onitemcreated="ListView1_ItemCreated" 
    onitemdatabound="ListView1_ItemDataBound">
    <LayoutTemplate>
        <table runat="server">
            <tr runat="server">
                <td runat="server">
                    <table ID="itemPlaceholderContainer" runat="server" border="0" style="">
                        <tr runat="server" style="">
                            <th runat="server">
                                UserName</th>
                            <th runat="server">
                                ProviderUserKey</th>   
                            <th></th>                     
                        </tr>
                        <tr ID="itemPlaceholder" runat="server">
                        </tr>
                    </table>
                </td>
            </tr>
            <tr runat="server">
                <td runat="server" style="">
                    <asp:DataPager ID="DataPager1" runat="server" PageSize="5">
                        <Fields>
                            <asp:NextPreviousPagerField ButtonType="Button" ShowFirstPageButton="True" 
                                ShowNextPageButton="False" ShowPreviousPageButton="False" />
                            <asp:NumericPagerField />
                            <asp:NextPreviousPagerField ButtonType="Button" ShowLastPageButton="True" 
                                ShowNextPageButton="False" ShowPreviousPageButton="False" />
                        </Fields>
                    </asp:DataPager>
                </td>
            </tr>
        </table>
    </LayoutTemplate>       
    <EmptyDataTemplate>
        <table runat="server" style="">
            <tr>
                <td>
                    No data was returned.</td>
            </tr>
        </table>
    </EmptyDataTemplate>    
    <ItemTemplate>
        <tr style="">
            <td>
                <asp:Label ID="UserNameLabel" runat="server" Text='<%# Eval("UserName") %>' />
            </td>
            <td>
                <asp:Label ID="ProviderUserKeyLabel" runat="server" 
                    Text='<%# Eval("ProviderUserKey") %>' />
            </td>
            <td>
                <asp:PlaceHolder ID="pl" runat="server"></asp:PlaceHolder>
            </td>
        </tr>
    </ItemTemplate>
</asp:ListView>
<asp:Label ID="lbMsg" runat="server"></asp:Label>
<asp:ObjectDataSource ID="ODS" runat="server" 
    SelectMethod="GetAllUsers" TypeName="SQLServerDAL.User" 
    EnablePaging="True" MaximumRowsParameterName="pageSize" 
    onselecting="ODS_Selecting" SelectCountMethod="GetUsersCount" 
    StartRowIndexParameterName="pageIndex">
    <SelectParameters>
        <asp:Parameter Name="pageIndex" Type="Int32" />
        <asp:Parameter Name="pageSize" Type="Int32" />
        <asp:Parameter Direction="Output" Name="totalRecords" Type="Int32" />
    </SelectParameters>
</asp:ObjectDataSource>

 

后台代码：

 

using System;
using System.Collections;
using System.Configuration;
using System.Data;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;
using System.Collections.Generic;

namespace Web.control
{
    public partial class RolesManage : System.Web.UI.UserControl
    {
        private int pageIndex;
        protected void Page_Load(object sender, EventArgs e)
        {
            if (!IsPostBack)
            {
                
            }
        }

        protected void ODS_Selecting(object sender, ObjectDataSourceSelectingEventArgs e)
        {
            if (!e.ExecutingSelectCount)
            {
                e.Arguments.MaximumRows = 5;
                e.Arguments.StartRowIndex = (pageIndex +1)/5;
            }

        }

        protected void ListView1_PagePropertiesChanging(object sender, PagePropertiesChangingEventArgs e)
        {
           
        }

        protected void ListView1_PagePropertiesChanged(object sender, EventArgs e)
        {
            pageIndex = ((DataPager)ListView1.FindControl("DataPager1")).StartRowIndex ;
            ODS.DataBind();
        }

        protected void ListView1_ItemCreated(object sender, ListViewItemEventArgs e)
        {
            if (e.Item.ItemType == ListViewItemType.DataItem)
            {
                string[] roles = System.Web.Security.Roles.GetAllRoles();

                PlaceHolder ph = (PlaceHolder)e.Item.FindControl("pl");
                Label lbProviderUserKeyLabel = (Label)e.Item.FindControl("ProviderUserKeyLabel");
                
                Control c = ParseControl(string.Format("<asp:CheckBoxList id='{0}' runat='server' />", "cbl1"));
                ph.Controls.Add(c);

                CheckBoxList cbl = (CheckBoxList)e.Item.FindControl("cbl1");
                cbl.RepeatDirection = RepeatDirection.Horizontal;   //水平显示
                  cbl.AutoPostBack = true;
                cbl.DataSource = roles;
                cbl.SelectedIndexChanged += new EventHandler(this.OnCblSelected);
            }
            
        }

        protected void OnCblSelected(object sender, EventArgs e)
        {
            CheckBoxList cbl = (CheckBoxList)sender;
            lbMsg.Text = cbl.ToolTip + "现在拥有以下角色：";
            ArrayList cblList = new ArrayList();
            foreach (ListItem l in cbl.Items)
            {
                if (l.Selected)
                {
                    cblList.Add(l.Text);
                    if (!DALFactory.DataAccess.GetRolesInstance().IsUserInRole(DALFactory.DataAccess.GetUserInstance().GetUser(cbl.ToolTip).UserName, l.Text))
                    {
                        DALFactory.DataAccess.GetRolesInstance().AddUserToRole(DALFactory.DataAccess.GetUserInstance().GetUser(cbl.ToolTip).UserName, l.Text);  //添加用户的角色
                    }
                }
                else
                {
                    if (DALFactory.DataAccess.GetRolesInstance().IsUserInRole(DALFactory.DataAccess.GetUserInstance().GetUser(cbl.ToolTip).UserName, l.Text))
                    {
                        DALFactory.DataAccess.GetRolesInstance().RemoveUserFromRole(DALFactory.DataAccess.GetUserInstance().GetUser(cbl.ToolTip).UserName, l.Text); //移除用户的角色
                    }
                }
            }
            foreach (String s in cblList)
            {
                lbMsg.Text += s+"、";
            }
            lbMsg.Text = lbMsg.Text.Substring(0, lbMsg.Text.LastIndexOf("、")); //截去最后的"、"号
        }

        protected void ListView1_ItemDataBound(object sender, ListViewItemEventArgs e)
        {
            if (e.Item.ItemType == ListViewItemType.DataItem)
            {
                Label lbUserNameLabel = (Label)e.Item.FindControl("UserNameLabel");
                CheckBoxList cbl = (CheckBoxList)e.Item.FindControl("cbl1");
                cbl.ToolTip = lbUserNameLabel.Text;
                string[] roles = DALFactory.DataAccess.GetRolesInstance().GetRolesForUser(lbUserNameLabel.Text);
                foreach (ListItem li in cbl.Items)
                {
                    li.Selected = roles.Contains(li.Text);
                }
            }
        }
        
    }
}