重写GridView支持数据筛选和自动排序功能

控件使用方法：

1.在页面Page_Load()方法的!Page.IsPostBack外面重新绑定数据源，即为DataSource赋值，因为页面回传时!Page.IsPostBack内的方法不会执行，先前赋值的DataSource为null。

2.将AllowSelecting属性设置为true

3.将AllowSorting属性设置为true，并为SortExpression赋值

筛选数据前图：

回车，筛选数据后图：

实现代码如下：

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Text;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Collections;
using System.Data;
using System.Reflection;
using System.Drawing.Design;

namespace WebCustomControls
{
    public class SupperGridView : System.Web.UI.WebControls.GridView
    {
        private Dictionary<string, string> dic = new Dictionary<string, string>();
        private GridViewRow selectorRow;

        public SupperGridView()
            : base()
        { }

        [DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden),Browsable(false)]
        public GridViewRow SelectorRow
        {
            get
            {
                if (selectorRow == null)
                {
                    this.EnsureChildControls();
                }
                return this.selectorRow;
            }
        }

        [DefaultValue(false)]
        public bool AllowSelecting
        {
            get
            {
                object o = ViewState["Selecting"];

                if (o != null)
                {
                    return (bool)o;
                }
                return false;
            }
            set
            {
                ViewState["Selecting"] = value;
            }
        }

        protected override int CreateChildControls(System.Collections.IEnumerable dataSource, bool dataBinding)
        {
            int num= base.CreateChildControls(dataSource, dataBinding);

            if (dataSource != null && AllowSelecting)
            {
                CreateSelectedRow();
            }

            return num;
        }

        // 创建数据筛选行 
        protected virtual void CreateSelectedRow()
        {
            if (this.Controls.Count != 0)
            {
                dic.Clear();
                Table table = (Table)this.Controls[0];
                TableRowCollection rows = table.Rows;
                selectorRow = CreateRow(0, 0, DataControlRowType.Header, DataControlRowState.Normal);
                selectorRow.ID = "SelectRow";
                TableCellCollection cells = selectorRow.Cells;

                for (int i = 0; i < Columns.Count; i++)
                {
                    TableCell cell = new TableCell();
                    TextBox box = new TextBox();
                    box.ID = "box" + i;
                    box.BorderStyle = BorderStyle.None;
                    box.AutoPostBack = true;
                    box.TextChanged += new EventHandler(box_TextChanged);
        
                    cell.Controls.Add(box);
                    cells.AddAt(i, cell);
                    dic.Add(box.ID, Columns[i].HeaderText);
                }
                rows.AddAt(1, selectorRow);
            }
        }

        private void box_TextChanged(object sender, EventArgs e)
        {
            if (DataSource == null) return;

            TextBox box = (TextBox)sender;
            DataTable table = SelectDataFromTextBox(box);

            if (table.Rows.Count == 0)
            {
                Page.ClientScript.RegisterClientScriptBlock(this.GetType(), this.GetType().FullName, "alert('对不起,没有您搜索的记录!')", true);
                return;
            }

            DataSource = table;
            DataBind();
        }

        //筛选数据逻辑，用linq实现可能给方便
        protected virtual DataTable SelectDataFromTextBox(TextBox box)
        {
            DataTable oldTable = ConvertToDataTable(GetData());
            DataTable newTable = oldTable.Clone();
            DataRow[] rows = null;
            Type columnDataType = oldTable.Columns[dic[box.ID]].DataType;
   
            // Column.DataType是string类型
            if (columnDataType == typeof(string))
            {
                rows = oldTable.Select("" + dic[box.ID] + " like '%" + box.Text + "%'");
            }
            // Column.DataType非string类型
            else
            {
                rows = oldTable.Select("" + dic[box.ID] + "='" + box.Text + "'");
            }

            foreach (DataRow row in rows)
            {
                newTable.Rows.Add(row.ItemArray);
            }
            return newTable;
        }

        //将IEnumerable数据类型转换成DataTable数据类型
        protected virtual DataTable ConvertToDataTable(IEnumerable data)
        {
            DataTable dtReturn = new DataTable();
            
            foreach (object item in data)
            {
                PropertyDescriptorCollection props = TypeDescriptor.GetProperties(item);

                foreach (PropertyDescriptor p in props)
                {
                    if (!dtReturn.Columns.Contains(p.Name))
                    {
                        dtReturn.Columns.Add(new DataColumn(p.Name, p.PropertyType));
                    }
                }

                DataRow row = dtReturn.NewRow();

                foreach (PropertyDescriptor p in props)
                {
                    row[p.Name] = p.GetValue(item);
                }

                dtReturn.Rows.Add(row);
            }
            return dtReturn;
        }

        //获取数据源，覆盖并重新实现父类方法 
        protected  new IEnumerable GetData()
        {
            DataSourceView dataSourceView = base.GetData();
            Type type = dataSourceView.GetType();
            MethodInfo method = type.GetMethod("ExecuteSelect", BindingFlags.NonPublic | BindingFlags.Public | BindingFlags.Instance);

            if (method == null) return null;

            object[] args = new object[] { DataSourceSelectArguments.Empty };
            object result = method.Invoke(dataSourceView, args);

            return (IEnumerable)result;
        }

        //为数据筛选行添加样式
        protected override void PrepareControlHierarchy()
        {
            base.PrepareControlHierarchy();

            if (this.Controls.Count != 0)
            {
                foreach (TableCell cell in selectorRow.Cells)
                {
                    if (cell != null && HeaderStyle != null)
                    {
                        cell.MergeStyle(HeaderStyle);
                    }
                }
            }
        }

        //重写排序方法 
        protected override void OnSorting(GridViewSortEventArgs e)
        {
            base.OnSorting(e);

            if (DataSource == null) return;

            DataView dataView = ConvertToDataTable(GetData()).DefaultView;

            ViewState["sortexpression"] = e.SortExpression;

            if (ViewState["sortdirection"] == null)
            {
                ViewState["sortdirection"] = "asc";
            }
            else
            {
                if (ViewState["sortdirection"].ToString() == "asc")
                {
                    ViewState["sortdirection"] = "desc";
                }
                else
                {
                    ViewState["sortdirection"] = "asc";
                }
            }

            if (ViewState["sortexpression"] != null)
            {
                dataView.Sort = ViewState["sortexpression"].ToString() + " " + ViewState["sortdirection"].ToString();
            }

            DataSource = dataView;
            DataBind();
        }
    }
}