ASP.Net2.0 GridView 多列排序，顯示排序圖標，分頁

    最近在使用ASP.net 2.0的GridView 控件時，發現排序與分頁功能Microsoft實現的都很簡單，比如排序，在點擊列名的時候來觸發整頁的PostBack，然后排序，但是在列頭上沒有一個顯示升序降序的圖標，這會讓最終用戶使用時很迷惑，因為不知道是升序了還是降序了，所以今天首先解決的第一問題就是升序降序在列上顯示圖標，第二要解決的問題是默認GridView按列排序只能排一列的，也就是不能進行多列排序，而在實際應用中僅僅按照一列來排序是不能滿足業務需求的，第三是GridView 分頁問題，GridView預定義的分頁頁碼顯示，比較簡單，而實際應用中，分頁可能不是只顯示首頁，上一頁，下一頁，末頁，或者是數字的頁碼那么簡單，應該更需要，跳轉，當前的頁碼，總頁數等，更詳盡的信息。

第一：GridView 多列排序與排序圖標顯示

首先我們可以新建一個類庫程序，主要需要引用System.Web.Dll文件
然后新建一個類，這個類繼承與GridView控件，我們只需要對部分方法進行重新即可。
我的演示的例子，采用了單列排序，如果啟用多列排序，把控件的AllowMultiColumnSorting設置為True就是
多列排序。

  1    public class WebGridView:GridView
  2    {
  3        屬性#region 屬性
  4        /**//// <summary>
  5        /// 是否啟用或者禁止多列排序
  6        /// </summary>
  7        [
  8        Description("是否啟用多列排序功能"),
  9        Category("排序"),
 10        DefaultValue("false"),
 11        ]
 12        public bool AllowMultiColumnSorting
 13        {
 14            get
 15            {
 16                object o = ViewState["EnableMultiColumnSorting"];
 17                return (o != null ? (bool)o : false);
 18            }
 19            set
 20            {
 21                AllowSorting = true;
 22                ViewState["EnableMultiColumnSorting"] = value;
 23            }
 24        }
 25        /**//// <summary>
 26        /// 升序時顯示圖標
 27        /// </summary>
 28        [
 29        Description("升序時顯示圖標"),
 30        Category("排序"),
 31        Editor("System.Web.UI.Design.UrlEditor", typeof(System.Drawing.Design.UITypeEditor)),
 32        DefaultValue(""),
 33
 34        ]
 35        public string SortAscImageUrl
 36        {
 37            get
 38            {
 39                object o = ViewState["SortImageAsc"];
 40                return (o != null ? o.ToString() : "");
 41            }
 42            set
 43            {
 44                ViewState["SortImageAsc"] = value;
 45            }
 46        }
 47        /**//// <summary>
 48        /// 降序時顯示圖標
 49        /// </summary>
 50        [
 51        Description("降序時顯示圖標"),
 52        Category("排序"),
 53        Editor("System.Web.UI.Design.UrlEditor", typeof(System.Drawing.Design.UITypeEditor)),
 54        DefaultValue(""),
 55        ]
 56        public string SortDescImageUrl
 57        {
 58            get
 59            {
 60                object o = ViewState["SortImageDesc"];
 61                return (o != null ? o.ToString() : "");
 62            }
 63            set
 64            {
 65                ViewState["SortImageDesc"] = value;
 66            }
 67        }
 68        #endregion
 69        重寫方法#region 重寫方法
 70        protected override void OnSorting(GridViewSortEventArgs e)
 71        {
 72            if (AllowMultiColumnSorting)
 73            {
 74                e.SortExpression = GetSortExpression(e);
 75            }
 76
 77            base.OnSorting(e);
 78        }
 79        protected override void OnRowCreated(GridViewRowEventArgs e)
 80        {
 81            if (e.Row.RowType == DataControlRowType.Header)
 82            {
 83                if (SortExpression != String.Empty)
 84                {
 85                    DisplaySortOrderImages(SortExpression, e.Row);
 86                    this.CreateRow(0, 0, DataControlRowType.EmptyDataRow, DataControlRowState.Normal);
 87                }
 88            }
 89            base.OnRowCreated(e);
 90        }
 91        #endregion
 92        受保護的方法#region 受保護的方法
 93        /**//// <summary>
 94        ///  獲取排序表達式
 95        /// </summary>
 96        protected string GetSortExpression(GridViewSortEventArgs e)
 97        {
 98            string[] sortColumns = null;
 99            string sortAttribute = SortExpression;
100
101            if (sortAttribute != String.Empty)
102            {
103                sortColumns = sortAttribute.Split(",".ToCharArray());
104            }
105            if (sortAttribute.IndexOf(e.SortExpression) > 0 || sortAttribute.StartsWith(e.SortExpression))
106            {
107                sortAttribute = ModifySortExpression(sortColumns, e.SortExpression);
108            }
109            else
110            {
111                sortAttribute += String.Concat(",", e.SortExpression, " ASC ");
112            }
113            return sortAttribute.TrimStart(",".ToCharArray()).TrimEnd(",".ToCharArray());
114
115        }
116        /**//// <summary>
117        ///  修改排序順序
118        /// </summary>
119        protected string ModifySortExpression(string[] sortColumns, string sortExpression)
120        {
121            string ascSortExpression = String.Concat(sortExpression, " ASC ");
122            string descSortExpression = String.Concat(sortExpression, " DESC ");
123
124            for (int i = 0; i < sortColumns.Length; i++)
125            {
126
127                if (ascSortExpression.Equals(sortColumns[i]))
128                {
129                    sortColumns[i] = descSortExpression;
130                }
131
132                else if (descSortExpression.Equals(sortColumns[i]))
133                {
134                    Array.Clear(sortColumns, i, 1);
135                }
136            }
137
138            return String.Join(",", sortColumns).Replace(",,", ",").TrimStart(",".ToCharArray());
139
140        }
141        /**//// <summary>
142        ///  獲取當前的表達式對所選列進行排序
143        /// </summary>
144        protected void SearchSortExpression(string[] sortColumns, string sortColumn, out string sortOrder, out int sortOrderNo)
145        {
146            sortOrder = "";
147            sortOrderNo = -1;
148            for (int i = 0; i < sortColumns.Length; i++)
149            {
150                if (sortColumns[i].StartsWith(sortColumn))
151                {
152                    sortOrderNo = i + 1;
153                    if (AllowMultiColumnSorting)
154                    {
155                        sortOrder = sortColumns[i].Substring(sortColumn.Length).Trim();
156                    }
157                    else
158                    {
159                        sortOrder = ((SortDirection == SortDirection.Ascending) ? "ASC" : "DESC");
160                    }
161                }
162            }
163        }
164        /**//// <summary>
165        ///  繪制升序降序的圖片
166        /// </summary>
167        protected void DisplaySortOrderImages(string sortExpression, GridViewRow dgItem)
168        {
169            string[] sortColumns = sortExpression.Split(",".ToCharArray());
170
171            for (int i = 0; i < dgItem.Cells.Count; i++)
172            {
173                if (dgItem.Cells[i].Controls.Count > 0 && dgItem.Cells[i].Controls[0] is LinkButton)
174                {
175                    string sortOrder;
176                    int sortOrderNo;
177                    string column = ((LinkButton)dgItem.Cells[i].Controls[0]).CommandArgument;
178                    SearchSortExpression(sortColumns, column, out sortOrder, out sortOrderNo);
179                    if (sortOrderNo > 0)
180                    {
181                        string sortImgLoc = (sortOrder.Equals("ASC") ? SortAscImageUrl : SortDescImageUrl);
182
183                        if (sortImgLoc != String.Empty)
184                        {
185                            Image imgSortDirection = new Image();
186                            imgSortDirection.ImageUrl = sortImgLoc;
187                            dgItem.Cells[i].Controls.Add(imgSortDirection);
188
189                        }
190                        else
191                        {
192
193                            if (AllowMultiColumnSorting)
194                            {
195                                Literal litSortSeq = new Literal();
196                                litSortSeq.Text = sortOrderNo.ToString();
197                                dgItem.Cells[i].Controls.Add(litSortSeq);
198
199                            }
200                        }
201                    }
202                }
203            }
204
205        }
206        #endregion
207    }

第二：詳盡的分頁信息顯示，此功能沒有封裝成控件形式，直接在GridView_DataBound事件中對尾頁操作即可。
下面是多列排序與分頁顯示代碼的演示

<script runat="server">
    void PageDropDownList_SelectedIndexChanged(Object sender, EventArgs e)
    {
        GridViewRow pagerRow = CustomersGridView.BottomPagerRow;
        DropDownList pageList = (DropDownList)pagerRow.Cells[0].FindControl("PageDropDownList");
        CustomersGridView.PageIndex = pageList.SelectedIndex;
    }
    void CustomersGridView_DataBound(Object sender, EventArgs e)
    {
        GridViewRow pagerRow = CustomersGridView.BottomPagerRow;
        LinkButton linkBtnFirst = (LinkButton)pagerRow.Cells[0].FindControl("linkBtnFirst");
        LinkButton linkBtnPrev = (LinkButton)pagerRow.Cells[0].FindControl("linkBtnPrev");
        LinkButton linkBtnNext = (LinkButton)pagerRow.Cells[0].FindControl("linkBtnNext");
        LinkButton linkBtnLast = (LinkButton)pagerRow.Cells[0].FindControl("linkBtnLast");
        if (CustomersGridView.PageIndex == 0)
        {
            linkBtnFirst.Enabled = false;
            linkBtnPrev.Enabled = false;
        }
        else if (CustomersGridView.PageIndex == CustomersGridView.PageCount-1)
        {
            linkBtnLast.Enabled  = false;
            linkBtnNext.Enabled = false;
        }
        else if (CustomersGridView.PageCount<=0)
        {
            linkBtnFirst.Enabled = false;
            linkBtnPrev.Enabled = false;
            linkBtnNext.Enabled = false;
            linkBtnLast.Enabled = false;
        }
        DropDownList pageList = (DropDownList)pagerRow.Cells[0].FindControl("PageDropDownList");
        Label pageLabel = (Label)pagerRow.Cells[0].FindControl("CurrentPageLabel");
        if (pageList != null)
        {
            for (int i = 0; i < CustomersGridView.PageCount; i++)
            {
                int pageNumber = i + 1;
                ListItem item = new ListItem(pageNumber.ToString() + "/" + CustomersGridView.PageCount.ToString(), pageNumber.ToString());
                if (i == CustomersGridView.PageIndex)
                {
                    item.Selected = true;
                }
                pageList.Items.Add(item);
            }
        }
        if (pageLabel != null)
        {
            int currentPage = CustomersGridView.PageIndex + 1;
            pageLabel.Text = "當前頁： " + currentPage.ToString() +
              " / " + CustomersGridView.PageCount.ToString();
        }
    }
</script>
<html>
<body>
    <form id="Form1" runat="server">
        <h3>
            GridView PagerTemplate Example</h3>
        <asp:WebGridView ID="CustomersGridView" DataSourceID="CustomersSqlDataSource" AutoGenerateColumns="true"
            AllowPaging="true" OnDataBound="CustomersGridView_DataBound" SortAscImageUrl="~\images\arrow-up.gif" SortDescImageUrl="~\images\arrow-down.gif" runat="server" AllowSorting="True" Width="723px">
            <PagerStyle ForeColor="Blue" BackColor="LightBlue" />
            <PagerTemplate>
                <table width="100%">
                    <tr>
                        <td width="70%">
                            <asp:Label ID="MessageLabel" ForeColor="Blue" Text="頁碼:" runat="server" />
                            <asp:DropDownList ID="PageDropDownList" AutoPostBack="true" OnSelectedIndexChanged="PageDropDownList_SelectedIndexChanged"
                                runat="server" />
                            <asp:LinkButton CommandName="Page" CommandArgument="First" ID="linkBtnFirst" runat="server">首頁</asp:LinkButton>
                            <asp:LinkButton CommandName="Page" CommandArgument="Prev" ID="linkBtnPrev" runat="server">上一頁</asp:LinkButton>
                            <asp:LinkButton CommandName="Page" CommandArgument="Next" ID="linkBtnNext" runat="server">下一頁</asp:LinkButton>
                            <asp:LinkButton CommandName="Page" CommandArgument="Last" ID="linkBtnLast" runat="server">末頁</asp:LinkButton>
                        </td>
                        <td width="70%" align="right">
                            <asp:Label ID="CurrentPageLabel" ForeColor="Blue" runat="server" />
                        </td>
                    </tr>
                </table>
            </PagerTemplate>
       </asp:WebGridView>
        <asp:SqlDataSource ID="CustomersSqlDataSource" SelectCommand="Select [CustomerID], [CompanyName], [Address], [City], [PostalCode], [Country] From [Customers]"
            ConnectionString="<%$ ConnectionStrings:NorthWindConnectionString%>" runat="server">
        </asp:SqlDataSource>
    </form>
</body>
</html>

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