我正在尝试压缩文件到流,这是通过wcf发送并解压缩的。但是,使用以下代码,在尝试执行解压缩的exe时,我得不到有效的exe。任何解压缩的exe都比原来的低了大约211-212个字节。
Sub Main()
Dim strm As Stream = CompressToStream("c:\rje\Launcher.exe")
DecompressToFile(strm)
End Sub
压缩例程
Private Function CompressToStream(ByVal strFullFilename As String) As Stream
If File.Exists(strFullFilename) Then
Dim uncompressedfile As New MemoryStream(File.ReadAllBytes(strFullFilename))
Dim compressedStream As New MemoryStream
Dim compressionStream As New GZipStream(compressedStream, CompressionMode.Compress)
uncompressedfile.CopyToStream(compressionStream)
compressionStream.Flush()
compressedStream.Position = 0
Return compressedStream
End If
Return Nothing
End Function
使用.net3.5
复制流的扩展方法<System.Runtime.CompilerServices.Extension()> _
Private Sub CopyToStream(ByVal input As Stream, ByRef output As Stream)
Dim Buffer(4096) As Byte
Dim numRead As Integer = input.Read(Buffer, 0, Buffer.Length)
Do While numRead <> 0
output.Write(Buffer, 0, numRead)
numRead = input.Read(Buffer, 0, Buffer.Length)
Loop
End Sub
最后解压缩
Private Sub DecompressToFile(ByVal strmDownload As Stream)
Dim spath As String = "c:\rje\text.exe"
Using outFile As FileStream = File.Create(spath)
Using Decompress As GZipStream = New GZipStream(strmDownload, CompressionMode.Decompress)
' Copy the compressed file into the decompression stream.
Dim buffer(4096) As Byte
Dim numRead As Integer = Decompress.Read(buffer, 0, buffer.Length)
Do While numRead <> 0
outFile.Write(buffer, 0, numRead)
numRead = Decompress.Read(buffer, 0, buffer.Length)
Loop
End Using
outFile.Close()
End Using
End Sub
如果有人能指出我出错的地方会很棒。
答案 0 :(得分:2)
错误发生在CompressToStream上,正确修改如下函数
Private Function CompressToStream(ByVal strFullFilename As String) As Stream
If File.Exists(strFullFilename) Then
Dim compressedStream As New MemoryStream()
Using uncompressedfile As New MemoryStream(File.ReadAllBytes(strFullFilename))
Using compressionStream As New GZipStream(compressedStream, CompressionMode.Compress, True)
uncompressedfile.CopyToStream(compressionStream)
End Using
End Using
compressedStream.Seek(0, SeekOrigin.Begin)
Return compressedStream
End If
Return Nothing
End Function
我仍然没有答案为什么我不应该使用File.Exists()?
答案 1 :(得分:0)
以下是我在评论中发布的链接中的示例中的Compress()/ Decompress()方法:
Private Function Compress(ByVal strFullFilename As FileInfo) As Stream
' Get the stream of the source file.
Dim fi as New FileInfo(strFullFilename)
Dim result As New MemoryStream()
Using inFile As FileStream = fi.OpenRead()
' Compressing:
' Prevent compressing hidden and already compressed files.
If (File.GetAttributes(fi.FullName) And FileAttributes.Hidden) _
<> FileAttributes.Hidden And fi.Extension <> ".gz" Then
' Create the compressed file.
Using Compress As GZipStream = New GZipStream(result, CompressionMode.Compress)
' Copy the source file into the compression stream.
Dim buffer As Byte() = New Byte(4096) {}
Dim numRead As Integer = inFile.Read(buffer, 0, buffer.Length)
Do While numRead <> 0
Compress.Write(buffer, 0, numRead)
numRead = inFile.Read(buffer, 0, buffer.Length)
Loop
'Console.WriteLine("Compressed {0} from {1} to {2} bytes.", fi.Name, fi.Length.ToString(), result.Length.ToString())
End Using
End If
End Using
Return result
End Sub
' Method to decompress.
Private Sub Decompress(ByVal strmDownload As Stream, ByVal resultFileName As String)
' Create the decompressed file.
Using outFile As FileStream = File.Create(resultFileName)
Using Decomp As GZipStream = New GZipStream(strmDownload, CompressionMode.Decompress)
' Copy the compressed file into the decompression stream.
Dim buffer As Byte() = New Byte(4096) {}
Dim numRead As Integer = Decompress.Read(buffer, 0, buffer.Length)
Do While numRead <> 0
outFile.Write(buffer, 0, numRead)
numRead = Decomp.Read(buffer, 0, buffer.Length)
Loop
'Console.WriteLine("Decompressed: {0}", fi.Name)
End Using
End Using
End Using
End Sub