我同意@DotNetDaddy 的观点,因为您需要确保在回发时设置数据源,因为这几乎肯定是“有趣”的黄屏死机的原因。下面是一个非常简单的示例,显示了 .NET 2.0+ 中 GridView 的排序和分页
以下是此 gridview 使用我的 vb 代码正常工作所需的确切标记
<asp:GridView ID="gridSuppliers" EnableViewState="false" runat="server" OnPageIndexChanging="gridSuppliers_PageIndexChanging" AutoGenerateColumns="false" AllowPaging="true" AllowSorting="true" CssClass="datatable" CellPadding="0" CellSpacing="0" BorderWidth="0" GridLines="None">...</asp:GridView>
接下来是代码隐藏文件,其中包含基于集合的数据绑定所需的排序/分页实现
Partial Public Class _Default
Inherits System.Web.UI.Page
Implements ISupplierView
Private presenter As SupplierPresenter
Protected Overrides Sub OnInit(ByVal e As System.EventArgs)
MyBase.OnInit(e)
presenter = New SupplierPresenter(Me)
End Sub
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
presenter.OnViewLoad()
End Sub
Protected Sub gridSuppliers_PageIndexChanging(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.GridViewPageEventArgs) Handles gridSuppliers.PageIndexChanging
gridSuppliers.PageIndex = e.NewPageIndex
presenter.PopulateSupplierList()
End Sub
Private Sub gridSuppliers_Sorting(ByVal sender As Object, ByVal e As GridViewSortEventArgs) Handles gridSuppliers.Sorting
If DirectCast(ViewState("PreviousSortExpression"), String) = e.SortExpression Then
If DirectCast(ViewState("PreviousSortDirection"), String) = "Ascending" Then
e.SortDirection = System.Web.UI.WebControls.SortDirection.Descending
ViewState("PreviousSortDirection") = "Descending"
Else
e.SortDirection = System.Web.UI.WebControls.SortDirection.Ascending
ViewState("PreviousSortDirection") = "Ascending"
End If
Else
e.SortDirection = System.Web.UI.WebControls.SortDirection.Ascending
ViewState("PreviousSortDirection") = "Ascending"
End If
ViewState("PreviousSortExpression") = e.SortExpression
Dim gv As GridView = DirectCast(sender, GridView)
If e.SortExpression.Length > 0 Then
For Each field As DataControlField In gv.Columns
If field.SortExpression = e.SortExpression Then
ViewState("PreviousHeaderIndex") = gv.Columns.IndexOf(field)
Exit For
End If
Next
End If
presenter.PopulateSupplierList()
End Sub
#Region "ISupplierView Properties"
Private ReadOnly Property PageIsPostBack() As Boolean Implements ISupplierView.PageIsPostBack
Get
Return Page.IsPostBack
End Get
End Property
Private ReadOnly Property SortExpression() As String Implements ISupplierView.SortExpression
Get
If ViewState("PreviousSortExpression") Is Nothing Then
ViewState("PreviousSortExpression") = "CompanyName"
End If
Return DirectCast(ViewState("PreviousSortExpression"), String)
End Get
End Property
Public ReadOnly Property SortDirection() As String Implements Library.ISupplierView.SortDirection
Get
If ViewState("PreviousSortDirection") Is Nothing Then
ViewState("PreviousSortDirection") = "Ascending"
End If
Return DirectCast(ViewState("PreviousSortDirection"), String)
End Get
End Property
Public Property Suppliers() As System.Collections.Generic.List(Of Library.Supplier) Implements Library.ISupplierView.Suppliers
Get
Return DirectCast(gridSuppliers.DataSource(), List(Of Supplier))
End Get
Set(ByVal value As System.Collections.Generic.List(Of Library.Supplier))
gridSuppliers.DataSource = value
gridSuppliers.DataBind()
End Set
End Property
#End Region
End Class
最后,代码隐藏中使用的演示者类
Public Class SupplierPresenter
Private mView As ISupplierView
Private mSupplierService As ISupplierService
Public Sub New(ByVal View As ISupplierView)
Me.New(View, New SupplierService())
End Sub
Public Sub New(ByVal View As ISupplierView, ByVal SupplierService As ISupplierService)
mView = View
mSupplierService = SupplierService
End Sub
Public Sub OnViewLoad()
If mView.PageIsPostBack = False Then
PopulateSupplierList()
End If
End Sub
Public Sub PopulateSupplierList()
Try
Dim SupplierList As List(Of Supplier) = mSupplierService.GetSuppliers()
SupplierList.Sort(New GenericComparer(Of Supplier)(mView.SortExpression, mView.SortDirection))
mView.Suppliers = SupplierList
Catch ex As Exception
Throw ex
End Try
End Sub
End Class
**对演示者中引用的通用集合进行排序所需的类
Imports System.Reflection
Imports System.Web.UI.WebControls
Public Class GenericComparer(Of T)
Implements IComparer(Of T)
Private mDirection As String
Private mExpression As String
Public Sub New(ByVal Expression As String, ByVal Direction As String)
mExpression = Expression
mDirection = Direction
End Sub
Public Function Compare(ByVal x As T, ByVal y As T) As Integer Implements System.Collections.Generic.IComparer(Of T).Compare
Dim propertyInfo As PropertyInfo = GetType(T).GetProperty(mExpression)
Dim obj1 As IComparable = DirectCast(propertyInfo.GetValue(x, Nothing), IComparable)
Dim obj2 As IComparable = DirectCast(propertyInfo.GetValue(y, Nothing), IComparable)
If mDirection = "Ascending" Then
Return obj1.CompareTo(obj2)
Else
Return obj2.CompareTo(obj1)
End If
End Function
End Class