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DataList實作分頁，排序功能

   DataList Web 伺服器控件以某種格式顯示資料，這種格式可以使用模闆和樣式進行定義。DataList 控件可用于任何重複結構中的資料，如表。DataList 控件可以以不同的布局顯示行，如按列或行對資料進行排序。DataList 控件不能自動利用資料源控件的更新功能以及自動分頁或排序。若要使用 DataList 控件執行更新、分頁和排序，必須在編寫的代碼中執行更新任務。

在PetShop4.0中，有一個叫做CustomList的類引起了我們的注意，它繼承了DataList類，并對其進行了改寫，實作了分頁功能，然而，PetShop4.0中對分頁功能較簡單（隻有上下翻頁功能），本文介紹PetShop4.0中DataList類的改寫思路，并對其進行進一步的研究。

一、效果圖

DataList實作分頁，排序功能

這個效果圖比較粗糙，讀者可以根據自己的需要，對其進行改寫。

二、具體改寫的代碼

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;上一頁</a></td>";

        private const string LINK_MORE = "<td><a href=?page={0}>下一頁&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);

            //清單資訊

            writer.Write("<td>共&nbsp;" + PageCount + "&nbsp;頁&nbsp;" + itemCount + "&nbsp項</td>");

            //導航到上一頁

            if (currentPageIndex > 0)

                writer.Write(string.Format(LINK_PREV, (currentPageIndex ) + query));

            else

            ...{

                writer.Write("<td>&nbsp;上一頁&nbsp;</td>");

            }

            //得到頁碼導航

            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) ));

                    }

                }

            //導航到下一頁

            if (currentPageIndex < PageCount)

                writer.Write(string.Format(LINK_MORE, (currentPageIndex + 2) + query));

            else

            ...{

                writer.Write("<td>&nbsp;下一頁&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、建立一個類庫工程，把上面代碼儲存為CustomList.cs,再重新生成，在工具欄便會多出一個使用者自定義元件。

DataList實作分頁，排序功能

四、對其進行調用

1.建立網站，在新頁面中拖拽一個CustomList元件。

2.對CustomList元件進行前台屬性設定

<%...@ 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>無标題頁</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.背景頁面程式綁定

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;

        //構造要作為資料源顯示的表

        DataTable dt = new DataTable("tabe1");

        DataColumn dc = new DataColumn("dc");

        dt.Columns.Add(dc);//構造一列

        for (int i = 1; i <= 100; i++)//循環加入資料

        ...{

            DataRow dr = dt.NewRow();

            dr["dc"] ="資料"+ i;

            dt.Rows.Add(dr);

        }

        //bind data

        productsList.DataSource = dt.DefaultView;

        productsList.DataBind();

    }

}

本文來自CSDN部落格，轉載請标明出處：http://blog.csdn.net/chenmintong/archive/2007/06/27/1669427.aspx

asp.net string query html constants table object
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