Web用户控件开发--分页控件

分页是Web应用程序中最常用到的功能之一，在ASP.NET中，虽然自带了一些可以分页的数据控件，但其分页功能并不尽如人意。本文对于这些数据控件的假分页暂且不表，如有不明白的同学请百Google度之。

本文中实现的分页控件是在手动分页基础上做的改善，将分页实现的逻辑部分和数据控件的绑定尽可能分开，以克服手工编写分页代码任务繁琐、代码重用率低等问题。

本文依旧是一粒粟子。

一、分页控件素颜

二、分页控件的实现

本文中将介绍两种将分页实现逻辑与数据控件绑定分离的实现方式：

• 使用反射机制
• 使用事件机制

1、基于反射机制的分页控件

源码：

PagingHelper.ascx：

<%@ Control Language="C#" AutoEventWireup="true" CodeBehind="PagingHelper.ascx.cs" Inherits="PagingHelper.Controls.PagingHelper" %>
<div style="width:100%">
    <asp:LinkButton ID="lbtnFirstPage" runat="server" CausesValidation="false" onclick="lbtnPage_Click"  >首页</asp:LinkButton>
    <asp:LinkButton ID="lbtnPrevPage" runat="server" CausesValidation="false"  onclick="lbtnPage_Click" >上一页</asp:LinkButton>
    &nbsp;第<asp:Label ID="lbPageIndex" runat="server" Text=""></asp:Label>
    页/共<asp:Label ID="lbTotalPages" runat="server" Text=""></asp:Label>
    页&nbsp;
    <asp:LinkButton ID="lbtnNextPage" runat="server" CausesValidation="false"  onclick="lbtnPage_Click" >下一页</asp:LinkButton>
    <asp:LinkButton ID="lbtnLastPage" runat="server" CausesValidation="false"  onclick="lbtnPage_Click" >尾页</asp:LinkButton>
</div>

PagingHelper.ascx.cs：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.HtmlControls;
using System.Reflection;

namespace PagingHelper.Controls
{
    public partial class PagingHelper : System.Web.UI.UserControl
    {
        #region 属性
        private int m_PageSize;
        public int PageSize         //每页显示记录数
        {
            set
            {
                m_PageSize = value;
            }
            get
            {
                if (m_PageSize.Equals(0))
                {
                    m_PageSize = 10;
                }
                return m_PageSize;
            }
        }

        private int m_PageIndex;
        public int PageIndex        //当前页页码
        {
            set
            {
                m_PageIndex = value;
            }
            get
            {
                if (m_PageIndex.Equals(0))
                {
                    m_PageIndex = 1;
                }
                return m_PageIndex;
            }
        }

        public int TotalItemCount   //记录总数
        {
            set;
            private get;
        }

        public string BindDataMethodName    //绑定数据的方法名
        {
            set;
            private get;
        }
        #endregion

        #region 受保护的方法
        protected void Page_Load(object sender, EventArgs e)
        {
            if (!IsPostBack)
            {
                BindPagingHelperControl();
            }
        }
        protected void lbtnPage_Click(object sender, EventArgs e)
        {
            LinkButton lbtn = sender as LinkButton;
            ReBindData(lbtn.CommandArgument);
        }
        #endregion

        #region 公共方法

        #endregion

        #region 私有方法
        private void BindPagingHelperControl()
        {
            int totalPages = (TotalItemCount % PageSize) == 0 ? TotalItemCount / PageSize : TotalItemCount / PageSize + 1;
            //显示
            lbPageIndex.Text = PageIndex.ToString();
            lbTotalPages.Text = totalPages.ToString();
            //使能
            lbtnFirstPage.Enabled = PageIndex > 1;
            lbtnPrevPage.Enabled =  PageIndex > 1;
            lbtnLastPage.Enabled = PageIndex < totalPages;
            lbtnNextPage.Enabled = PageIndex < totalPages;
            //命令
            lbtnFirstPage.CommandArgument = "1";
            lbtnPrevPage.CommandArgument = (PageIndex - 1).ToString();
            lbtnNextPage.CommandArgument = (PageIndex + 1).ToString();
            lbtnLastPage.CommandArgument = totalPages.ToString();
        }
        private void ReBindData(string pageIndex)
        {
            PageIndex = int.Parse(pageIndex);
            Object obj = null;  //空间所在的容器
            if (base.Parent is HtmlForm)
            {
                obj = this.Page;
            }
            else if (base.Parent is ContentPlaceHolder)
            {
                obj = this.Page.Master.Page;
            }
            else
            {
                obj = base.Parent;
            }
            MethodInfo methodInfo = obj.GetType().GetMethod(BindDataMethodName, BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic);
            methodInfo.Invoke(obj, null);
            BindPagingHelperControl();
        }
        #endregion

    }
}

Demo：

Default.aspx：

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

<%@ Register src="Controls/PagingHelper.ascx" tagname="PagingHelper" tagprefix="uc1" %>

<!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></title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <asp:GridView ID="gvDemo" runat="server">
        </asp:GridView>
        <br />
        <uc1:PagingHelper ID="PagingHelper1" runat="server" PageSize="2" />
    </div>
    </form>
</body>
</html>

Default.aspx.cs：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data;

namespace PagingHelper
{
    public partial class Default : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            GvDemoBind();
        }

        protected void GvDemoBind()
        {
            string sql = @"SELECT * FROM tb_user";
            string sqlCount = @"SELECT COUNT(*) FROM tb_user ";
            int itemStart = (PagingHelper1.PageIndex - 1) * PagingHelper1.PageSize;
            sql += string.Format(" LIMIT {0},{1}",itemStart,PagingHelper1.PageSize);
            gvDemo.DataSource = SQLHelper.ExecuteDataTable(sql).DefaultView;
            gvDemo.DataBind();
            PagingHelper1.TotalItemCount = Convert.ToInt32(SQLHelper.ExecuteScalar(sqlCount));
            PagingHelper1.BindDataMethodName = "GvDemoBind";
        }
    }
}

2、基于事件机制的分页控件

源码：

PagingHelper.ascx：

<%@ Control Language="C#" AutoEventWireup="true" CodeBehind="PagingHelper.ascx.cs" Inherits="PagingHelper_V2.Controls.PagingHelper" %>
<div style="width:100%">
    <asp:LinkButton ID="lbtnFirstPage" runat="server" CausesValidation="false" onclick="lbtnPage_Click"  >首页</asp:LinkButton>
    <asp:LinkButton ID="lbtnPrevPage" runat="server" CausesValidation="false"  onclick="lbtnPage_Click" >上一页</asp:LinkButton>
    &nbsp;第<asp:Label ID="lbPageIndex" runat="server" Text=""></asp:Label>
    页/共<asp:Label ID="lbTotalPages" runat="server" Text=""></asp:Label>
    页&nbsp;
    <asp:LinkButton ID="lbtnNextPage" runat="server" CausesValidation="false"  onclick="lbtnPage_Click" >下一页</asp:LinkButton>
    <asp:LinkButton ID="lbtnLastPage" runat="server" CausesValidation="false"  onclick="lbtnPage_Click" >尾页</asp:LinkButton>
    &nbsp;转到
    <asp:TextBox ID="txtGoto" runat="server" Width="32px"></asp:TextBox>
    页<asp:Button ID="btnGoto" runat="server" Text="确定" onclick="btnGoto_Click" />
</div>

PagingHelper.ascx.cs：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.HtmlControls;

namespace PagingHelper_V2.Controls
{
    public partial class PagingHelper : System.Web.UI.UserControl
    {
        #region 属性
        private int m_PageSize;
        public int PageSize         //每页显示记录数
        {
            set
            {
                m_PageSize = value;
            }
            get
            {
                if (m_PageSize.Equals(0))
                {
                    m_PageSize = 10;
                }
                return m_PageSize;
            }
        }

        private int m_PageIndex;
        public int PageIndex        //当前页页码
        {
            set
            {
                m_PageIndex = value;
            }
            get
            {
                if (m_PageIndex.Equals(0))
                {
                    m_PageIndex = 1;
                }
                return m_PageIndex;
            }
        }

        public int TotalItemCount   //记录总数
        {
            set;
            private get;
        }

        #endregion

        #region 受保护的方法
        protected void Page_Load(object sender, EventArgs e)
        {
            if (!IsPostBack)
            {
                BindPagingHelperControl();
            }
        }
        protected void lbtnPage_Click(object sender, EventArgs e)
        {
            LinkButton lbtn = sender as LinkButton;
            ReBindData(int.Parse(lbtn.CommandArgument));
        }
        protected void btnGoto_Click(object sender, EventArgs e)
        {
            int gotoPageIndex = PageIndex;
            if (int.TryParse(txtGoto.Text, out gotoPageIndex))
            {
                if (gotoPageIndex < 1 || gotoPageIndex > int.Parse(lbTotalPages.Text))
                {
                    Response.Write("<script>alert('此页面不存在！')</script>");
                }
                else
                {
                    if (!gotoPageIndex.Equals(int.Parse(lbPageIndex.Text)))
                    {
                        ReBindData(gotoPageIndex);
                    }
                }
            }
            else
            {
                Response.Write("<script>alert('请输入正确的页码！')</script>");
            }

        }
        #endregion

        #region 公共方法

        #endregion

        #region 私有方法
        private void BindPagingHelperControl()
        {
            int totalPages = (TotalItemCount % PageSize) == 0 ? TotalItemCount / PageSize : TotalItemCount / PageSize + 1;
            //显示
            lbPageIndex.Text = PageIndex.ToString();
            lbTotalPages.Text = totalPages.ToString();
            txtGoto.Text = PageIndex.ToString();
            //使能
            lbtnFirstPage.Enabled = PageIndex > 1;
            lbtnPrevPage.Enabled = PageIndex > 1;
            lbtnLastPage.Enabled = PageIndex < totalPages;
            lbtnNextPage.Enabled = PageIndex < totalPages;
            //命令
            lbtnFirstPage.CommandArgument = "1";
            lbtnPrevPage.CommandArgument = (PageIndex - 1).ToString();
            lbtnNextPage.CommandArgument = (PageIndex + 1).ToString();
            lbtnLastPage.CommandArgument = totalPages.ToString();
        }
        private void ReBindData(int pageIndex)
        {
            PageIndex = pageIndex;
            OnPageIndexChanged(new EventArgs());
            BindPagingHelperControl();
        }
        #endregion

        #region 事件
        public delegate void PageIndexChangedEventHandler(object sender, EventArgs e);
        public event PageIndexChangedEventHandler PageIndexChanged;
        protected virtual void OnPageIndexChanged(EventArgs e)
        {
            PageIndexChangedEventHandler handler = PageIndexChanged;
            if (handler != null)
            {
                handler(this, e);
            }
        }
        #endregion


    }
}

Demo：

Default.aspx：

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="PagingHelper_V2.Default" %>

<%@ Register src="Controls/PagingHelper.ascx" tagname="PagingHelper" tagprefix="uc1" %>

<!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></title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <asp:GridView ID="gvDemo" runat="server">
        </asp:GridView>
        &nbsp;
        <uc1:PagingHelper ID="PagingHelper1" runat="server" PageSize="2" OnPageIndexChanged="PagingHelper1_OnPageIndexChanged" />
    </div>
    </form>
</body>
</html>

Default.aspx.cs：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

namespace PagingHelper_V2
{
    public partial class Default : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            GvDemoBind();
        }

        protected void GvDemoBind()
        {
            string sql = @"SELECT * FROM tb_user";
            string sqlCount = @"SELECT COUNT(*) FROM tb_user ";
            int itemStart = (PagingHelper1.PageIndex - 1) * PagingHelper1.PageSize;
            sql += string.Format(" LIMIT {0},{1}", itemStart, PagingHelper1.PageSize);
            gvDemo.DataSource = SQLHelper.ExecuteDataTable(sql).DefaultView;
            gvDemo.DataBind();
            PagingHelper1.TotalItemCount = Convert.ToInt32(SQLHelper.ExecuteScalar(sqlCount));

        }

        protected void PagingHelper1_OnPageIndexChanged(object sender, EventArgs e)
        {
            GvDemoBind();
        }
    }
}

三、总结

比较两种实现方式，基于事件机制的实现更符合ASP.NET服务器控件的style。

好！那就参照园子里的分页使用基于事件机制的方式再做一个控件作为总结。

源码：

PagingHelper.ascx：

<%@ Control Language="C#" AutoEventWireup="true" CodeBehind="PagingHelper.ascx.cs" Inherits="PagingHelper_V3.Controls.PagingHelper" %>
<style type="text/css">
    a.LinkButtonDefault{text-align:center;text-decoration:none;margin-right:1px;padding:2px 4px;}
    a.LinkButtonBlue{background: #ebebeb;text-align:center;text-decoration:none;margin-right:1px;padding:2px 4px;}
    a.LinkButtonYellow { background-color:#ccc; color:#000fff; font-weight:bold;text-align:center;text-decoration:none;margin-right:1px;padding:2px 4px;}
</style>
<div style="width:100%">
    共<asp:Label ID="lbTotalPages" runat="server" ForeColor="#fff"></asp:Label>页：
    <asp:LinkButton ID="lbtnFirstPage" runat="server" CausesValidation="false" CssClass="LinkButtonDefault" onclick="lbtnPage_Click" >首页</asp:LinkButton>
    <asp:LinkButton ID="lbtnPrevPage" runat="server" CausesValidation="false" CssClass="LinkButtonDefault" onclick="lbtnPage_Click" >上一页</asp:LinkButton>
    <asp:Repeater ID="rptPageNumber" runat="server">
        <ItemTemplate>
            <asp:LinkButton ID="lbtnPageNumber" runat="server" CausesValidation="false" Width="16px" onclick="lbtnPage_Click"
                 CssClass='<%# Convert.ToInt32(Container.DataItem)==PageIndex?"LinkButtonYellow":"LinkButtonBlue"%>' CommandArgument='<%# Container.DataItem %>'>
<%
 #Container.DataItem
%>
            </asp:LinkButton>
        </ItemTemplate>
    </asp:Repeater>
    <asp:LinkButton ID="lbtnNextPage" runat="server" CausesValidation="false" CssClass="LinkButtonDefault"  onclick="lbtnPage_Click" >下一页</asp:LinkButton>
    <asp:LinkButton ID="lbtnLastPage" runat="server" CausesValidation="false" CssClass="LinkButtonDefault"  onclick="lbtnPage_Click" >尾页</asp:LinkButton>
</div>

PagingHelper.ascx.cs：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

namespace PagingHelper_V3.Controls
{
    public partial class PagingHelper : System.Web.UI.UserControl
    {
        #region 属性
        private int m_PageSize;
        public int PageSize         //每页显示记录数
        {
            set
            {
                m_PageSize = value;
            }
            get
            {
                if (m_PageSize.Equals(0))
                {
                    m_PageSize = 10;
                }
                return m_PageSize;
            }
        }

        private int m_PageIndex;
        public int PageIndex        //当前页页码
        {
            set
            {
                m_PageIndex = value;
            }
            get
            {
                if (m_PageIndex.Equals(0))
                {
                    m_PageIndex = 1;
                }
                return m_PageIndex;
            }
        }

        public int TotalItemCount   //记录总数
        {
            set;
            private get;
        }

        #endregion

        #region 受保护的方法
        protected void Page_Load(object sender, EventArgs e)
        {
            if (!IsPostBack)
            {
                BindPagingHelperControl();
            }
        }
        protected void lbtnPage_Click(object sender, EventArgs e)
        {
            LinkButton lbtn = sender as LinkButton;
            ReBindData(int.Parse(lbtn.CommandArgument));
        }
        #endregion

        #region 公共方法

        #endregion

        #region 私有方法
        private void BindPageNum(int totalPages)
        {
            int startPageIndex = 1, endPageIndex = 10;
            if (totalPages < endPageIndex)
            {
                endPageIndex = totalPages;
            }
            else
            {
                startPageIndex = (PageIndex > 5) ? PageIndex - 5 : startPageIndex;
                int result = (startPageIndex + 9) - totalPages;
                if (result > 0)
                {
                    endPageIndex = totalPages;
                    startPageIndex -= result;
                }
                else
                {
                    endPageIndex = startPageIndex + 9;
                }
            }
            BindPageNum(startPageIndex, endPageIndex);
        }
        private void BindPageNum(int startPageIndex, int endPageIndex)
        {
            int[] pages = new int[endPageIndex - startPageIndex + 1];
            int index = 0;
            for (int i = startPageIndex; i <= endPageIndex; i++)
            {
                pages[index] = i;
                index++;
            }
            rptPageNumber.DataSource = pages;
            rptPageNumber.DataBind();
        }
        private void BindPagingHelperControl()
        {
            int totalPages = (TotalItemCount % PageSize) == 0 ? TotalItemCount / PageSize : TotalItemCount / PageSize + 1;
            //显示
            lbTotalPages.Text = totalPages.ToString();
            BindPageNum(totalPages);
            //使能
            lbtnFirstPage.Enabled = PageIndex > 1;
            lbtnPrevPage.Enabled = PageIndex > 1;
            lbtnLastPage.Enabled = PageIndex < totalPages;
            lbtnNextPage.Enabled = PageIndex < totalPages;
            //命令
            lbtnFirstPage.CommandArgument = "1";
            lbtnPrevPage.CommandArgument = (PageIndex - 1).ToString();
            lbtnNextPage.CommandArgument = (PageIndex + 1).ToString();
            lbtnLastPage.CommandArgument = totalPages.ToString();
        }
        private void ReBindData(int pageIndex)
        {
            PageIndex = pageIndex;
            OnPageIndexChanged(new EventArgs());
            BindPagingHelperControl();
        }
        #endregion

        #region 事件
        public delegate void PageIndexChangedEventHandler(object sender, EventArgs e);
        public event PageIndexChangedEventHandler PageIndexChanged;
        protected virtual void OnPageIndexChanged(EventArgs e)
        {
            PageIndexChangedEventHandler handler = PageIndexChanged;
            if (handler != null)
            {
                handler(this, e);
            }
        }
        #endregion
    }
}