GridView自定義分頁---派生類(1)

数据量很大时，使用gridview内置的分頁功能，页面加载会非常的慢，此处自定义分頁是在需要时才加载当页数据。

using System;

using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Data.SqlClient;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Reflection;
using System.Text.RegularExpressions;

namespace MyWeb.WebControls
{
    /// <summary>
    /// 自定GridView分頁
    /// 元件使用說明：
    ///
    ///  1.特性說明
    ///  
    /// 【SelectCommand: 查詢字符串】
    /// 【OrderBy: 排序字符串】
    /// 【AllowCustPaging: 是否允許分頁。Default:true】
    /// 【ShowRecordCount：是否顯示查詢結果筆數。Default:true】
    /// 【ShowExportExcelButton: 是否匯出excel。Default:false】
    /// 【ExportExcelHiddenColIndex: 匯出Excel時需隱藏欄位。ex:7,8】
    /// 【ExportExcelClearControlIndex：清除gridview列中控件。ex:0,3】
    ///
    ///  2.方法說明
    ///  
    ///  public void ReDataBind() //重新綁定所有資料
    /// </summary>
    public class GridViewPage : GridView
    {
         
        #region 屬性宣告

        private bool _setNewCommand = false;

        /// <summary>
        /// 查詢的SQL Command
        /// </summary>
        [Browsable(false)]
        public string SelectCommand
        {
            set
            {
                ViewState["Command"] = value;
                CurrentPage = 1;

                if (_setNewCommand)
                {
                    SetDataSource(false);
                    _setNewCommand = false;
                }
                else
                {
                    _setNewCommand = true;
                }
            }
            get
            {
                return (string)ViewState["Command"] ?? "";
            }
        }

        /// <summary>
        /// 查詢排序
        /// </summary>
        [Browsable(false)]
        public string OrderBy
        {
            set
            {
                ViewState["OrderBy"] = value;
                 
                if (_setNewCommand)
                {
                    SetDataSource(false);
                    _setNewCommand = false;
                }
                else
                {
                    _setNewCommand = true;
                }
            }
            get
            {
                return (string)ViewState["OrderBy"] ?? "";
            }
        }

        /// <summary>
        /// 取得或設定資料控制項從中擷取資料項目清單的物件
        /// </summary>
        public override object DataSource
        {
            get
            {
                return base.DataSource;
            }
            set
            {
                base.DataSource = value;

                if (SelectCommand.IsEmpty() && OrderBy.IsEmpty() && value is DataTable)
                {
                    TotalCount = ((DataTable)value).Rows.Count;
                    TotalPage = TotalCount >0 ? 1 : 0;
                }
            }
        }

        /// <summary>
        /// 是否顯示匯出excel 按鈕
        /// </summary>
        [Description("是否顯示匯出excel 按鈕"), Category("CustomAttribute")]
        public bool ShowExportExcelButton
        {
            set { ViewState["ShowExportExcelButton"] = value; }
            get { return ViewState["ShowExportExcelButton"] == null ? false : (bool)ViewState["ShowExportExcelButton"]; }
        }

        /// <summary>
        /// 是否顯示查詢結果筆數
        /// </summary>
        [Description("是否顯示查詢結果筆數"),Category("CustomAttribute")]
        public bool ShowRecordCount
        {
            set { ViewState["ShowRecordCount"] = value; }
            get { return ViewState["ShowRecordCount"] == null ? true : (bool)ViewState["ShowRecordCount"]; }
        }

        /// <summary>
        /// 是否允許分頁
        /// </summary>
        [Description("是否允許分頁"),Category("CustomAttribute")]
        public bool AllowCustPaging
        {
            set { ViewState["AllowCustPaging"] = value; }
            get { return ViewState["AllowCustPaging"] == null ? true : (bool)ViewState["AllowCustPaging"]; }
        }
         
        /// <summary>
        /// 清除gridview列中控件
        /// </summary>
        [Description("清除gridview列中控件(ex:0,3)"),Category("CustomAttribute")]
        public string ExportExcelClearControlIndex
        {
            set { ViewState["ExportExcelClearControlIndex"] = value; }
            get { return (string)ViewState["ExportExcelClearControlIndex"] ?? ""; }
        }

        /// <summary>
        /// 匯出excel需隱藏的列
        /// </summary>
        [Description("匯出excel需隱藏的列(ex:0,3)"),Category("CustomAttribute")]
        public string ExportExcelHiddenColIndex
        {
            set { ViewState["ExportExcelHiddenColIndex"] = value; }
            get { return (string)ViewState["ExportExcelHiddenColIndex"] ?? ""; }
        }
         
        protected string EmptyTableRowText
        {
            get
            {
                object o = ViewState["EmptyTableRowText"];
                return (o != null ? o.ToString() : "");
            }
            set
            {
                ViewState["EmptyTableRowText"] = value;
            }
        }

        /// <summary>
        /// 是否自動建立欄位
        /// </summary>
        public override bool AutoGenerateColumns
        {
            get
            {
                return false;
            }
            set
            {
                base.AutoGenerateColumns = value;
            }
        }
        /// <summary>
        /// 資料總頁數
        /// </summary>
        protected int TotalPage
        {
            set { ViewState["TotalPage"] = value; }
            get { return ViewState["TotalPage"] == null ? -1 : (int)ViewState["TotalPage"]; }
        }

        /// <summary>
        /// 當前頁數
        /// </summary>
        [Browsable(false)]
        public int CurrentPage
        {
            set { ViewState["CurrentPage"] = value; }
            get { return ViewState["CurrentPage"] == null ? 1 : (int)ViewState["CurrentPage"]; }
        }
         
        /// <summary>
        /// 資料總筆數
        /// </summary>
        [Browsable(false)]
        public int TotalCount
        {
            set { ViewState["TotalCount"] = value; }
            get { return ViewState["TotalCount"] == null ? -1 : (int)ViewState["TotalCount"]; }
        }
 
        #endregion