ASP.NET中的分页剖析(四)

这里我们把前面的代码重构为用户控件的方式来使用，提高代码的利用率。

用户控件PagerControl.ascx的页面的设计图如下：

用户控件PagerControl.ascx的页面代码如下：

<%@ Control Language="C#" AutoEventWireup="true" CodeFile="PagerControl.ascx.cs" Inherits="_Controls_PagerControl" %>

 <div class="contentstyle" style="text-align:center;margin:20px 0 20px 0;">
            <asp:Label ID="lblMessage" runat="server" Text="msg" Height="25px" Font-Size="15" ></asp:Label>&nbsp;
            <asp:Button ID="btnFirstPage" runat="server" Text="首页" Width="48px"
                Height="25px" onclick="btnFirstPage_Click" />&nbsp;
            <asp:Button ID="btnPreviousPage" runat="server" Text="上一页" Width="48px"
                Height="25px" onclick="btnPreviousPage_Click" />&nbsp;
            <asp:Button ID="btnNextPage" runat="server" Text="下一页" Width="48px"
                Height="25px" onclick="btnNextPage_Click" />&nbsp;
            <asp:Button ID="btnLastPage" runat="server" Text="末页" Width="48px"
                Height="25px" onclick="btnLastPage_Click" />&nbsp;
            <span style="font-size:12px; font-style:italic; font-weight:bold;">页大小:</span>
            <asp:TextBox ID="txtPageSize" runat="server" Width="25px" Height="25px"></asp:TextBox>
            <span style="font-size:12px; font-style:italic; font-weight:bold;">
            <asp:RequiredFieldValidator ID="rfvTxtPageSize" runat="server"
                ControlToValidate="txtPageSize" ErrorMessage="页面记录大小不能为空！">*</asp:RequiredFieldValidator>
            <asp:RangeValidator ID="rvTxtPageSize" runat="server"
                ControlToValidate="txtPageSize" ErrorMessage="页面记录大小必须大于零且不大于当前记录数！"
                MinimumValue="1" Type="Integer">*</asp:RangeValidator>
            跳到:</span>
            <asp:TextBox ID="txtCurrentPageIndex" runat="server" Width="25px" Height="25px"></asp:TextBox>
            <span style="font-size:12px; font-style:italic; font-weight:bold;">
            <asp:RequiredFieldValidator ID="rfvTxtCPI" runat="server"
                ControlToValidate="txtCurrentPageIndex" ErrorMessage="跳转页不能为空！">*</asp:RequiredFieldValidator>
            <asp:RangeValidator ID="rvTxtCPI" runat="server" BorderStyle="None"
                ControlToValidate="txtCurrentPageIndex" ErrorMessage="输入页必须大于零且不大于当前页面数！"
                MinimumValue="1" Type="Integer">*</asp:RangeValidator>
            页</span>
            <asp:Button ID="btnTurnPage" runat="server" Text="GO" Width="25px"
                Height="25px" onclick="btnTurnPage_Click" />
            <asp:ValidationSummary ID="ValidationSummary1" runat="server"
                ShowMessageBox="True" ShowSummary="False" />
        </div>

对应的PagerControl.ascx.cs业务逻辑文件代码如下：

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

public partial class _Controls_PagerControl : System.Web.UI.UserControl
{
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            rvTxtPageSize.MaximumValue = RecordCount.ToString();
            rvTxtCPI.MaximumValue = PageCount.ToString();

            SetCurrentStatus();
        }
        else
        {
            rvTxtPageSize.MaximumValue = RecordCount.ToString();
            rvTxtCPI.MaximumValue = PageCount.ToString();
        }
    }

    /// <summary>
    /// 页面是否改变
    /// </summary>
    private bool pagerChanged = false;
    public bool PagerChanged
    {
        get { return pagerChanged; }
        set { pagerChanged = value; }
    }

    /// <summary>
    /// 当前页索引号
    /// </summary>
    public int Pager
    {
        get { return (int)ViewState["Page"]; }
        set { ViewState["Page"] = value; }
    }

    /// <summary>
    /// 分页大小
    /// </summary>
    public int PageSize
    {
        get { return (int)ViewState["PageSize"]; }
        set { ViewState["PageSize"] = value; }
    }

    /// <summary>
    /// 记录数量
    /// </summary>
    public int RecordCount
    {
        get
        {
            return (int)ViewState["RecordCount"];
        }
        set
        {
            ViewState["RecordCount"] = value;
        }
    }

    /// <summary>
    /// 总页数
    /// </summary>
    public int PageCount
    {
        get
        {
            return (int)Math.Ceiling((double)RecordCount / PageSize);
        }
    }

    protected void btnFirstPage_Click(object sender, EventArgs e)
    {
        pagerChanged = true;
        PageSize = Convert.ToInt32(txtPageSize.Text.Trim());
        Pager = 1;
        SetCurrentStatus();
    }
    protected void btnPreviousPage_Click(object sender, EventArgs e)
    {
        pagerChanged = true;
        PageSize = Convert.ToInt32(txtPageSize.Text.Trim());
        Pager--;
        SetCurrentStatus();
    }
    protected void btnNextPage_Click(object sender, EventArgs e)
    {
        pagerChanged = true;
        PageSize = Convert.ToInt32(txtPageSize.Text.Trim());
        Pager++;
        SetCurrentStatus();
    }
    protected void btnLastPage_Click(object sender, EventArgs e)
    {
        pagerChanged = true;
        PageSize = Convert.ToInt32(txtPageSize.Text.Trim());
        Pager = PageCount;
        SetCurrentStatus();
    }
    protected void btnTurnPage_Click(object sender, EventArgs e)
    {
        pagerChanged = true;
        Pager = Convert.ToInt32(txtCurrentPageIndex.Text.Trim());
        PageSize = Convert.ToInt32(txtPageSize.Text.Trim());
        SetCurrentStatus();
    }

    private void SetCurrentStatus()
    {
        if (Pager == 1 && Pager == PageCount)
        {
            btnFirstPage.Enabled = false;
            btnPreviousPage.Enabled = false;
            btnNextPage.Enabled = false;
            btnLastPage.Enabled = false;
        }
        else
        {
            if (Pager == 1)
            {
                btnFirstPage.Enabled = false;
                btnPreviousPage.Enabled = false;
                btnNextPage.Enabled = true;
                btnLastPage.Enabled = true;
            }
            else if (Pager == PageCount)
            {
                btnFirstPage.Enabled = true;
                btnPreviousPage.Enabled = true;
                btnNextPage.Enabled = false;
                btnLastPage.Enabled = false;
            }
            else
            {
                btnFirstPage.Enabled = true;
                btnPreviousPage.Enabled = true;
                btnNextPage.Enabled = true;
                btnLastPage.Enabled = true;
            }
        }

        txtCurrentPageIndex.Text = Pager.ToString();
        txtPageSize.Text = PageSize.ToString();
        lblMessage.Text = "当前页：" + Pager + "共" + PageCount + "页";
    }
}

使用分页用户控件的.aspx页面代码如下：

<%@ Register src="_Controls/PagerControl.ascx" tagname="PagerControl" tagprefix="uc1" %>

<div class="contentstyle" style="text-align:center;margin:20px 0 20px 0;">      
            <uc1:PagerControl ID="PagerControl1" runat="server" />
</div>

使用分页用户控件的.aspx.cs业务逻辑文件代码如下：

public partial class BookList_UserPagerControl : System.Web.UI.Page
{   
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            //首次加载，赋初值
            try
            {
                ViewState["typeid"] = Convert.ToInt32(Request.QueryString["typeid"]);
            }
            catch
            {
                ViewState["typeid"] = -1;
            }

            this.PagerControl1.RecordCount = BookManager.GetBooksCountByCategoryId(Convert.ToInt32(ViewState["typeid"]));
            btnChangeOrder.Enabled = false;
            this.PagerControl1.Pager = 1;
            this.PagerControl1.PageSize = 10;
            BindData();
        }
    }

    /// <summary>
    /// 获得封面的url
    /// </summary>
    /// <param name="isbn"></param>
    /// <returns></returns>
    public string GetUrl(string isbn)
    {
        return StringHandler.CoverUrl(isbn);
    }
    /// <summary>
    /// 截断图书显示内容
    /// </summary>
    /// <param name="content"></param>
    /// <param name="num"></param>
    /// <returns></returns>
    public string GetCut(string content, int num)
    {
        return StringHandler.CutString(content, num);
    }

    #region  排序
    protected void btnDate_Click(object sender, EventArgs e)
    {
        if (btnPrice.Enabled)
        {
            btnPrice.Enabled = false;
            btnPrice.BackColor = Color.Gray;

            if (!btnChangeOrder.Enabled)
            {
                btnChangeOrder.Enabled = true;
            }
        }

        string publishDateOrder = (string)ViewState["Order"];
        if (publishDateOrder == null)
        {
            ViewState["Order"] = "PublishDate";
            btnDate.Text = "出版日期↑";
        }
        else
        {
            if (publishDateOrder.Equals("PublishDate"))
            {
                ViewState["Order"] = "PublishDate Desc";
                btnDate.Text = "出版日期↓";
            }
            else
            {
                ViewState["Order"] = "PublishDate";
                btnDate.Text = "出版日期↑";
            }
        }

        this.PagerControl1.Pager = 1;
        BindData();
    }

    protected void btnPrice_Click(object sender, EventArgs e)
    {
        if (btnDate.Enabled)
        {
            btnDate.Enabled = false;
            btnDate.BackColor = Color.Gray;

            if (!btnChangeOrder.Enabled)
            {
                btnChangeOrder.Enabled = true;
            }
        }
        string unitPriceOrder = (string)ViewState["Order"];
        if (unitPriceOrder == null)
        {
            ViewState["Order"] = "UnitPrice";
            btnPrice.Text = "价格↑";
        }
        else
        {
            if (unitPriceOrder.Equals("UnitPrice"))
            {
                ViewState["Order"] = "UnitPrice Desc";
                btnPrice.Text = "价格↓";
            }
            else
            {
                ViewState["Order"] = "UnitPrice";
                btnPrice.Text = "价格↑";
            }
        }

        this.PagerControl1.Pager = 1;
        BindData();
    }
    #endregion

    private void BindData()
    {
        int currentPageIndex = this.PagerControl1.Pager;
        int pageSize = this.PagerControl1.PageSize;
        IList<Book> books;
        if (this.PagerControl1.Pager == this.PagerControl1.PageCount)
        {
            books = BookManager.GetCurrentPageBooksByCategoryId((currentPageIndex - 1) * pageSize + 1, this.PagerControl1.RecordCount, Convert.ToInt32(ViewState["typeid"]), (string)ViewState["Order"]);
        }
        else
        {
            books = BookManager.GetCurrentPageBooksByCategoryId((currentPageIndex - 1) * pageSize + 1, currentPageIndex * pageSize, Convert.ToInt32(ViewState["typeid"]), (string)ViewState["Order"]);
        }

        dlBooks.DataSource = books;
        dlBooks.DataBind();
    }
    protected void btnChangeOrder_Click(object sender, EventArgs e)
    {
        if (btnDate.Enabled)
        {
            btnDate.Enabled = false;
            btnDate.BackColor = Color.Gray;
        }
        else
        {
            btnDate.Enabled = true;
            btnDate.BackColor = Color.FromArgb(192, 255, 192);
            if (btnDate.Text.Trim().Equals("出版日期↑"))
            {
                ViewState["Order"] = "PublishDate";
            }
            else
            {
                ViewState["Order"] = "PublishDate Desc";
            }

            this.PagerControl1.Pager = 1;
            BindData();
        }
        if (btnPrice.Enabled)
        {
            btnPrice.Enabled = false;
            btnPrice.BackColor = Color.Gray;
        }
        else
        {
            btnPrice.Enabled = true;
            btnPrice.BackColor = Color.FromArgb(192, 255, 192);
            if (btnPrice.Text.Trim().Equals("价格↑"))
            {
                ViewState["Order"] = "UnitPrice";
            }
            else
            {
                ViewState["Order"] = "UnitPrice Desc";
            }

            this.PagerControl1.Pager = 1;
            BindData();
        }
    }
    protected void dlBooks_PreRender(object sender, EventArgs e)
    {
        if (this.PagerControl1.PagerChanged)
        {
            this.PagerControl1.PagerChanged = false;
            this.PagerControl1.RecordCount = BookManager.GetBooksCountByCategoryId(Convert.ToInt32(ViewState["typeid"]));
            BindData();
        }
    }
}

DAL获得记录数量方法代码如下：

        public static int GetBooksCountByCategoryId(int categoryId)
        {
            string sql = string.Empty;
            if (categoryId > 0)
            {
                sql = "select count(*) from Books where CategoryId=" + categoryId;
            }
            else
            {
                sql = "select count(*) from Books";
            }
            int bookCount = DBHelper.GetScalar(sql);
            return bookCount;
        }

好了，这一篇就到这里吧！这几篇的叙述少了些，源码多了些，相信大家对这些代码能够看懂，有什么不懂的地方给我留言吧！下一篇准备把基于SQL语句的数据获取方式重构为存储过程来实现。【待续...】