我刚刚开始在VB.Net COM pressing文件，使用下面的code。因为我针对Fx的2.0，我不能使用 Stream.CopyTo 方法。

I've just started compressing file in VB.Net, using the following code. Since I'm targeting Fx 2.0, I can't use the Stream.CopyTo method.

我的code，但是，给人非常不好的结果相比，GZIP 正常 COM pression在7-ZIP轮廓。例如，我的code COM pressed一个630MB的前景存档740MB，而7-ZIP使得它490MB。

My code, however, gives extremely poor results compared to the gzip Normal compression profile in 7-zip. For example, my code compressed a 630MB outlook archive to 740MB, and 7-zip makes it 490MB.

下面是code。是否有一个赤裸裸的错误（或多个？）

Here is the code. Is there a blatant mistake (or many?)

Using Input As New IO.FileStream(SourceFile, IO.FileMode.Open, IO.FileAccess.Read, IO.FileShare.Read)
    Using outFile As IO.FileStream = IO.File.Create(DestFile)
        Using Compress As IO.Compression.GZipStream = New IO.Compression.GZipStream(outFile, IO.Compression.CompressionMode.Compress)
            'TODO: Figure out the right buffer size.'
            Dim Buffer(524228) As Byte
            Dim ReadBytes As Integer = 0

            While True
                ReadBytes = Input.Read(Buffer, 0, Buffer.Length)
                If ReadBytes <= 0 Then Exit While
                Compress.Write(Buffer, 0, ReadBytes)
            End While
        End Using
    End Using
End Using

我已经试过多个缓冲区大小，但我得到类似COM pression倍，并具有完全相同的COM pression比。

I've tried with multiple buffer sizes, but I get similar compression times, and exactly the same compression ratio.

推荐答案

修改，或者实际上改写：它看起来像BCL codeRS决定的