自定义datalist分页(转)

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 + "&nbsp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">

</head>

<body>

<cc1:CustomList ID="productsList" runat="server" EmptyText="No products found." OnPageIndexChanged="PageChanged" PageSize="12" RepeatColumns="1" CellPadding="4" Width="400px" CurrentPageIndex="1" ForeColor="#333333">

<tr>

</tr>

</table>

</ItemTemplate>

</cc1:CustomList>

</form>

</body>

</html>

22.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();

}

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posted @ 2007-09-07 11:49 子午阅读(590) 评论(1) 编辑收藏举报

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