How to Persist Variable on Postback

Public intFileID As Integer = 0

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
    If Not Page.IsPostBack Then
        If Not Request.QueryString("fileid") Is Nothing Then
            intFileID = CInt(Request.QueryString("fileid"))
        End If

        If intFileID > 0 Then
            GetFile(intFileID)
        End If
    End If
End Sub

Private Sub GetFile()
    'uses intFileID to retrieve the specific record from database and set's the various textbox.text
End Sub

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
    If Not Page.IsPostBack Then
    	If Not Request.QueryString("fileid") Is Nothing Then
    		intFileID = CInt(Request.QueryString("fileid"))
    	End If

    	If intFileID > 0 Then
    		GetFile(intFileID)
    	End If

    	ViewState("intFileID") = intFileID
    Else
    	intFileID = ViewState("intFileID")
    End If
End Sub

ViewState(key) = value

value = ViewState(key)

Page.Session["MyPage_FileID"] = intFileID

Private intFileId As Integer = 0

Public Property FileID() As Integer
    Get
        Return intFileId
    End Get
    Set(ByVal value As Integer)
        intFileId = value
    End Set
End Property


Protected Overrides Function SaveControlState() As Object
    Dim objState(2) As Object
    objState(0) = MyBase.SaveControlState()
    objState(1) = Me.FileID
    Return objState
End Function


Protected Overrides Sub LoadControlState(ByVal savedState As Object)
    Dim objState() As Object
    objState = savedState
    MyBase.LoadControlState(objState(0))
    Me.FileID = CInt(objState(1))
End Sub




Protected Sub Page_Init(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Init
    Me.Page.RegisterRequiresControlState(Me)
End Sub


Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load

    If Not Page.IsPostBack Then
        If Not String.IsNullOrEmpty(Request.QueryString("fileid")) Then
            Me.FileID = CInt(Request.QueryString("fileid"))
        End If
    End If

    Response.Write(Me.FileID.ToString())
End Sub