函數名：ResponseFile
功能  ：客戶端從服務器端下載一個文件
返回值：返回True表示服務器響應成功，返回False表示失敗
參數  ：
        PageResponse       響應客戶端的Response對象，用Page.Response引用
        DownloadFileName   客戶端下載文件的文件名
        LocalFilePath      服務器端待下載文件的路徑
        DownloadBuffer     服務器端讀取文件的緩沖區大小，單位為KB
Public Function ResponseFile(ByRef PageResponse As HttpResponse, ByVal DownloadFileName As String, ByVal LocalFilePath As String, ByVal DownloadBuffer As Long) As Boolean
        Dim Reader As System.IO.FileStream
        Dim Buffer() As Byte
        Dim FileLength As Long
        Dim FileBuffer As Long = 1024 * DownloadBuffer
        Dim ReadCount As Long
        ReadCount = FileBuffer
        ReDim Buffer(ReadCount - 1)
        Try
                Reader = System.IO.File.OpenRead(LocalFilePath)
                FileLength = Reader.Length
                Try
                        PageResponse.Buffer = False
                        PageResponse.AddHeader("Connection", "Keep-Alive")
                        PageResponse.ContentType = "application/octet-stream"
                        PageResponse.AddHeader("Content-Disposition", "attachment;filename=" + DownloadFileName)
                        PageResponse.AddHeader("Content-Length", FileLength.ToString)
                        While ReadCount = FileBuffer
                                ReadCount = Reader.Read(Buffer, 0, FileBuffer)
                                ReDim Preserve Buffer(ReadCount - 1)
                                PageResponse.BinaryWrite(Buffer)
                        End While
                        Response.End()
                Catch ex As Exception
                        Return False
                Finally
                        Reader.Close()
                End Try
        Catch ex As Exception
                Return False
        End Try
        Return True
End Function