檔案下載function

        Public Function ResponseFile(ByVal FRequest As HttpRequest, ByVal FResponse As HttpResponse, ByVal fileName As String, ByVal fullPath As String, ByVal speed As Long) As Boolean
            Try
                Dim myFile As FileStream = New FileStream(fullPath, FileMode.Open, FileAccess.Read, FileShare.ReadWrite)
                Dim br As BinaryReader = New BinaryReader(myFile)
                Try
                    FResponse.AddHeader("Accept-Ranges", "bytes")

                    FResponse.Buffer = False '關閉存後送出
                    Dim fileLength As Long = myFile.Length
                    Dim startBytes As Long = 0

                    Dim pack As Integer = 10240  '10K bytes
                    'int sleep = 200;   //每秒5次   即5*10K bytes每秒
                    Dim sleep As Integer = CType(Math.Floor(1000 * pack / speed) + 1, Integer)
                    If (FRequest.Headers("Range") <> Nothing) Then
                        FResponse.StatusCode = 206
                        Dim range() As String = FRequest.Headers("Range").Split(New Char() {"="c, "-"c})
                        startBytes = Convert.ToInt64(range(1))

                    End If
                    FResponse.AddHeader("Content-Length", (fileLength - startBytes).ToString())
                    If (startBytes <> 0) Then
                        FResponse.AddHeader("Content-Range", String.Format(" bytes {0}-{1}/{2}", startBytes, fileLength - 1, fileLength))
                    End If
                    FResponse.AddHeader("Connection", "Keep-Alive")
                    FResponse.ContentType = "application/octet-stream"
                    FResponse.AddHeader("Content-Disposition", "attachment;filename=" + HttpUtility.UrlEncode(fileName, System.Text.Encoding.UTF8))

                    br.BaseStream.Seek(startBytes, SeekOrigin.Begin)
                    Dim maxCount As Integer = CType(Math.Floor((fileLength - startBytes) / pack) + 1, Integer)
                    Dim i As Integer
                    For i = 0 To maxCount - 1 Step i + 1
                        If (FResponse.IsClientConnected) Then
                            FResponse.BinaryWrite(br.ReadBytes(pack))
                            Thread.Sleep(sleep)
                        Else
                            i = maxCount
                        End If
                    Next
                Catch
                    Return False
                Finally
                    br.Close()
                    myFile.Close()
                End Try
            Catch
                Return False
            End Try
            Return True
        End Function

調用代碼如下:

        Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
            Dim FunName As String = Request("FunName")
            Dim TableName As String = Request("TableName")
            Dim TablePriKey As String = Request("TablePriKey")
            Dim FilePathStr As String = Request("FilePathStr")
            Dim id As Integer = Request("id")
            Dim sql As String = "select count(*) from WebFileDownCount where FunName='" & FunName & "'"
            If Me.ExecString.ExecSQLScalar(sql) = 0 Then
                Me.ExecString.ExecSQLNoneQuery("insert into WebFileDownCount (FunName,DownNum) values ('" & FunName & "',1)")
            Else
                Me.ExecString.ExecSQLNoneQuery("update WebFileDownCount set DownNum=DownNum+1 where FunName='" & FunName & "'")
            End If
            Dim sql2 = "select " & FilePathStr & " from " & TableName & " where " & TablePriKey & "=" & id
            '直接打開
            'Dim FileUrl As String = Me.ExecString.ExecSQLScalar(sql2)
            'Response.Redirect(Server.UrlEncode(FileUrl))
            '作為資料流輸出
            Dim fileurl As String = Me.ExecString.ExecSQLScalar(sql2)
            Dim filename As String = Right(fileurl, fileurl.Length - fileurl.LastIndexOf("/") - 1)
            Page.Response.Clear()
            Me.ResponseFile(Page.Request, Page.Response, filename, Server.MapPath(fileurl), 10240)
            Page.Response.End()
        End Sub