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}> 上一页</a></td>";
private const string LINK_MORE = "<td><a href=?page={0}>下一页 </a></td>";
private const string LINK_DISPLAY = "<td><a href=?page={0}> {1} </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 " + PageCount + " 页 " + itemCount + " 项</td>");
//导航到上一页
if (currentPageIndex > 0)
writer.Write(string.Format(LINK_PREV, (currentPageIndex ) + query));
else
...{
writer.Write("<td> 上一页 </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> " + (currentPageIndex+1) + " </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> 下一页 </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