有一个程序,其中有一段利用DataGrid控件排序的代码段,viewstate("sortexp"),搞不懂,不知道是怎么来的,请高手详细解释一下.谢谢了!Private Sub ManageDBGrd_SortCommand(ByVal source As Object, ByVal e As System.Web.UI.WebControls.DataGridSortCommandEventArgs) Handles ManageDBGrd.SortCommand
If viewstate("sortexp") Is Nothing Then
viewstate("sortexp") = e.SortExpression.ToString
ElseIf viewstate("sortexp") = e.SortExpression.ToString Then
viewstate("sortexp") += " desc"
Else
viewstate("sortexp") = e.SortExpression.ToString
End If
BindData()
End Sub
If viewstate("sortexp") Is Nothing Then
viewstate("sortexp") = e.SortExpression.ToString
ElseIf viewstate("sortexp") = e.SortExpression.ToString Then
viewstate("sortexp") += " desc"
Else
viewstate("sortexp") = e.SortExpression.ToString
End If
BindData()
End Sub
viewstate是对象集合,viewstate(key,value)
直到当前页面关闭就会自动释放,和SESSION有点相识。只是数据在本页面可以使用。不能跨页面