DataList实现分页，排序功能

   DataList Web 服务器控件以某种格式显示数据，这种格式可以使用模板和样式进行定义。DataList 控件可用于任何重复结构中的数据，如表。DataList 控件可以以不同的布局显示行，如按列或行对数据进行排序。DataList 控件不能自动利用数据源控件的更新功能以及自动分页或排序。若要使用 DataList 控件执行更新、分页和排序，必须在编写的代码中执行更新任务。

在PetShop4.0中，有一个叫做CustomList的类引起了我们的注意，它继承了DataList类，并对其进行了改写，实现了分页功能，然而，PetShop4.0中对分页功能较简单（只有上下翻页功能），本文介绍PetShop4.0中DataList类的改写思路，并对其进行进一步的研究。

一、效果图

这个效果图比较粗糙，读者可以根据自己的需要，对其进行改写。

二、具体改写的代码

using System;
using System.Collections;
using System.Collections.Specialized;
using System.Text;
using System.Text.RegularExpressions;
using System.Web.UI;
using System.Web.UI.WebControls;

namespace CustomList ...{

    public class CustomList : DataList ...{
        //Static constants
        private string HTML1 = "<table cellpadding=0 cellspacing=0 ><tr><td colspan=13>";
        protected const string HTML2 = "</td></tr><tr>";
        protected const string HTML4 = "</tr></table>";
        private static readonly Regex RX = new Regex(@"^&page=d+", RegexOptions.Compiled);
        private const string LINK_PREV = "<td><a href=?page={0}>&nbsp;上一页</a></td>";
        private const string LINK_MORE = "<td><a href=?page={0}>下一页&nbsp;</a></td>";
        private const string LINK_DISPLAY = "<td><a href=?page={0}>&nbsp;{1}&nbsp;</a></td>";
        private const string KEY_PAGE = "page";
        private const string COMMA = "?";
        private const string AMP = "&";
      
        protected string emptyText;
        private IList dataSource;
        private int pageSize = 10;
        private int currentPageIndex;
        private int itemCount;
 

 

        override public object DataSource ...{
            set ...{
                //This try catch block is to avoid issues with the VS.NET designer
                //The designer will try and bind a datasource which does not derive from ILIST
                try ...{
                    dataSource = (IList)value;
                    ItemCount = dataSource.Count;
                }
                catch ...{
                    dataSource = null;
                    ItemCount = 0;
                }
            }
        }

        public int PageSize ...{
            get ...{ return pageSize; }
            set ...{ pageSize = value; }
        }

        protected int PageCount ...{
            get ...{ return (ItemCount - 1) / pageSize; }
        }

        virtual protected int ItemCount ...{
            get ...{ return itemCount; }
            set ...{ itemCount = value; }
        }

        virtual public int CurrentPageIndex ...{
            get ...{ return currentPageIndex; }
            set ...{ currentPageIndex = value; }
        }

        public string EmptyText ...{
            set ...{ emptyText = value; }
        }

        public void SetPage(int index) ...{
            OnPageIndexChanged(new DataGridPageChangedEventArgs(null, index));
        }

        override protected void OnLoad(EventArgs e) ...{
            if (Visible) ...{
                string page = Context.Request[KEY_PAGE];
                int index = (page != null) ? int.Parse(page)-1 : 0;
                SetPage(index);
            }
        }

        /**//// <summary>
        /// Overriden method to control how the page is rendered
        /// </summary>
        /// <param name="writer"></param>
        override protected void Render(HtmlTextWriter writer) ...{

            //Check there is some data attached
            if (ItemCount == 0) ...{
                writer.Write(emptyText);
                return;
            }

            //Mask the query
            string query = Context.Request.Url.Query.Replace(COMMA, AMP);
            query = RX.Replace(query, string.Empty);

            // Write out the first part of the control, the table header
            writer.Write(HTML1);

            // Call the inherited method
            base.Render(writer);

           
            // Write out a table row closure
            writer.Write(HTML2);

            //列表信息
            writer.Write("<td>共&nbsp;" + PageCount + "&nbsp;页&nbsp;" + itemCount + "&nbsp项</td>");
            //导航到上一页
            if (currentPageIndex > 0)
                writer.Write(string.Format(LINK_PREV, (currentPageIndex ) + query));
            else
            ...{
                writer.Write("<td>&nbsp;上一页&nbsp;</td>");
            }

            //得到页码导航
            for (int i =0; i <= 9 && i <= PageCount && (currentPageIndex - currentPageIndex % 10 + i)<=PageCount ; i++)
                ...{
                    if (currentPageIndex - currentPageIndex % 10 + i == currentPageIndex)
                    ...{
                        writer.Write("<td>&nbsp;" + (currentPageIndex+1) + "&nbsp;</td>");
                    }
                    else
                    ...{
                        writer.Write(string.Format(LINK_DISPLAY, (currentPageIndex - currentPageIndex % 10 + i+1) + query,(currentPageIndex - currentPageIndex % 10 + i+1) ));

                    }
                }
          
            //导航到下一页
            if (currentPageIndex < PageCount)
                writer.Write(string.Format(LINK_MORE, (currentPageIndex + 2) + query));
            else
            ...{
                writer.Write("<td>&nbsp;下一页&nbsp;</td>");
            }

            //Close the table
            writer.Write(HTML4);
        }

        override protected void OnDataBinding(EventArgs e) ...{

            //Work out which items we want to render to the page
            int start = CurrentPageIndex * pageSize;
            int size = Math.Min(pageSize, ItemCount - start);

            IList page = new ArrayList();

            //Add the relevant items from the datasource
            for (int i = 0; i < size; i++)
                page.Add(dataSource[start + i]);

            //set the base objects datasource
            base.DataSource = page;
            base.OnDataBinding(e);

        }

        public event DataGridPageChangedEventHandler PageIndexChanged;

        virtual protected void OnPageIndexChanged(DataGridPageChangedEventArgs e) ...{
            if (PageIndexChanged != null)
                PageIndexChanged(this, e);
        }
    }
}
三、新建一个类库工程，把上面代码保存为CustomList.cs,再重新生成，在工具栏便会多出一个用户自定义组件。

四、对其进行调用

1.新建网站，在新页面中拖拽一个CustomList组件。

2.对CustomList组件进行前台属性设置

<%...@ Page Language="C#" AutoEventWireup="true"  CodeFile="Default.aspx.cs" Inherits="_Default" %>

<%...@ Register Assembly="CustomList" Namespace="CustomList" TagPrefix="cc1" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
    <title>无标题页</title>
</head>
<body>
    <form id="form1" runat="server">

        <cc1:CustomList ID="productsList" runat="server"  EmptyText="No products found." OnPageIndexChanged="PageChanged" PageSize="12" RepeatColumns="1" CellPadding="4" Width="400px" CurrentPageIndex="1" ForeColor="#333333">
                        <ItemTemplate>
            <table cellpadding="0" cellspacing="0">
                <tr>
                    <td valign="top" width="400px" align="center" ><%...# Eval("dc")%></td>
                   
                                     
                </tr>              
            </table>           
        </ItemTemplate>
            <FooterStyle BackColor="#990000" Font-Bold="True" ForeColor="White" />
            <SelectedItemStyle BackColor="#FFCC66" Font-Bold="True" ForeColor="Navy" />
            <AlternatingItemStyle BackColor="White" />
            <ItemStyle BackColor="#FFFBD6" ForeColor="#333333" />
            <HeaderStyle BackColor="#990000" Font-Bold="True" ForeColor="White" />
        </cc1:CustomList>
    </form>
</body>
</html>
3.后台页面程序绑定

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Collections;
public partial class _Default : System.Web.UI.Page
...{
    protected void Page_Load(object sender, EventArgs e)
    ...{
    }
    protected void PageChanged(object sender, DataGridPageChangedEventArgs e)
    ...{
        //reset index
        productsList.CurrentPageIndex = e.NewPageIndex;

        //构造要作为数据源显示的表
        DataTable dt = new DataTable("tabe1");
        DataColumn dc = new DataColumn("dc");
        dt.Columns.Add(dc);//构造一列
        for (int i = 1; i <= 100; i++)//循环加入数据
        ...{
            DataRow dr = dt.NewRow();
            dr["dc"] ="数据"+ i;
            dt.Rows.Add(dr);

        }

        //bind data
        productsList.DataSource = dt.DefaultView;
        productsList.DataBind();

    }
}

本文来自CSDN博客，转载请标明出处：http://blog.csdn.net/chenmintong/archive/2007/06/27/1669427.aspx