GridView动态构建OrderBy进行排序

<asp:GridView ID="GridView1" runat="server" AllowSorting="true" 
    AutoGenerateColumns="false" onsorting="GridView1_Sorting">
    <Columns>
        <asp:BoundField HeaderText="Column1" DataField="Field1" SortExpression="Field1" />
        <asp:BoundField HeaderText="Column2" DataField="Field2" SortExpression="Field2" />
    </Columns>
</asp:GridView>

[Serializable]
public class TestClass
{
    public int Field1 { get; set; }
    public int Field2 { get; set; }
}

protected void Page_Load(object sender, EventArgs e)
{
    List<TestClass> oData = new List<TestClass>();
    for (int i = 1; i <= 10; i++)
    {
        TestClass t = new TestClass() { Field1 = i, Field2 = 11 - i };
        oData.Add(t);
    }
    ViewState["Data"] = oData;
    this.GridView1.DataSource = oData;
    this.GridView1.DataBind();
}

protected void GridView1_Sorting(object sender, GridViewSortEventArgs e)
{
    //从ViewState取得绑定在界面的数据源
    List<TestClass> oDatas = (List<TestClass>)ViewState["Data"];
    
    //从Session取得当前字段的排序状态
    if (Session[e.SortExpression] == null)
    {
        Session[e.SortExpression] = SortDirection.Ascending;
    }

    //判断当前，如果为升序，则以倒序排序一次，如果为倒序，则以升序排序一次，并更新当前排序
    //动态的重点在于利用反射，根据e.SortExpression取得排序栏位
    if ((SortDirection)Session[e.SortExpression] == SortDirection.Ascending)
    {
        oDatas = oDatas.OrderBy(c => c.GetType().GetProperty(e.SortExpression).GetValue(c, null)).ToList();
        Session[e.SortExpression] = SortDirection.Descending;
    }
    else
    {
        oDatas = oDatas.OrderByDescending(c => c.GetType().GetProperty(e.SortExpression).GetValue(c, null)).ToList();
        Session[e.SortExpression] = SortDirection.Ascending;
    }

    //重新绑定一次排序後的数据以显示结果
    GridView gv = sender as GridView;
    gv.DataSource = oDatas;
    gv.DataBind();
}