CompressionMode Enumeration
Specifies whether to compress or decompress the underlying stream.
Assembly: System (in System.dll)
This enumeration is used with the GZipStream and DeflateStream classes.
The following code example uses the CompressionMode enumeration with the GZipStream class to compress and decompress a file.
Imports System.IO Imports System.IO.Compression Module Module1 Sub Main() ' Path to directory of files to compress. Dim dirpath As String = "c:\users\public\reports" Dim di As DirectoryInfo = New DirectoryInfo(dirpath) ' Compress the directory's files. For Each fi As FileInfo In di.GetFiles() Compress(fi) Next ' Decompress all *.gz files in the directory. For Each fi As FileInfo In di.GetFiles("*.gz") Decompress(fi) Next End Sub ' Method to compress. Private Sub Compress(ByVal fi As FileInfo) ' Get the stream of the source file. 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 outFile As FileStream = File.Create(fi.FullName + ".gz") Using Compress As GZipStream = New GZipStream(outFile, CompressionMode.Compress) ' Copy the source file into the compression stream. Dim buffer As Byte() = New Byte(4096) {} Dim numRead As Integer numRead = 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(), outFile.Length.ToString()) End Using End Using End If End Using End Sub ' Method to decompress. Private Sub Decompress(ByVal fi As FileInfo) ' Get the stream of the source file. Using inFile As FileStream = fi.OpenRead() ' Get orignial file extension, for example "doc" from report.doc.gz. Dim curFile As String = fi.FullName Dim origName = curFile.Remove(curFile.Length - fi.Extension.Length) ' Create the decompressed file. Using outFile As FileStream = File.Create(origName) Using Decompress As GZipStream = New GZipStream(inFile, CompressionMode.Decompress) ' Copy the compressed file into the decompression stream. Dim buffer As Byte() = New Byte(4096) {} Dim numRead As Integer numRead = Decompress.Read(buffer, 0, buffer.Length) Do While numRead <> 0 outFile.Write(buffer, 0, numRead) numRead = Decompress.Read(buffer, 0, buffer.Length) Loop Console.WriteLine("Decompressed: {0}", fi.Name) End Using End Using End Using End Sub End Module
Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC, Xbox 360, Zune
The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.
