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
