函数名：ResponseFile
功能  ：客户端从服务器端下载一个文件
返回值：返回True表示服务器响应成功，返回False表示失败
参数  ：
        PageResponse       响应客户端的Response对象，用Page.Response引用
        DownloadFileName   客户端下载文件的文件名
        LocalFilePath      服务器端待下载文件的路径
        DownloadBuffer     服务器端读取文件的缓冲区大小，单位为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