Public Class frmCompress
    Public Sub subZipFile(ByVal strFile As String, Optional ByVal strZipFile As String = "")
        Try
            ' Existiert die Datei überhaupt
            If File.Exists(strFile) Then
                ' Falls keine Zieldatei angegeben, Quelldatei mit Endung ".gzip" annehmen
                If strZipFile.Length = 0 Then
                    With New FileInfo(strFile)
                        strZipFile = .DirectoryName
                        If Not strZipFile.EndsWith("\") Then strZipFile += "\"
                        strZipFile += .Name.Substring(0, .Name.Length - .Extension.Length) & ".gzip"
                    End With
                End If

                ' Inhalt der Datei einlesen
                Dim oStream As FileStream
                oStream = New FileStream(strFile, IO.FileMode.Open)
                Dim bBuffer(oStream.Length - 1) As Byte
                With oStream
                    .Read(bBuffer, 0, bBuffer.Length)
                    .Close()
                End With

                ' Jetzt Daten komprimieren und in Zieldatei speichern
                oStream = New FileStream(strZipFile, IO.FileMode.Create)
                Dim oCompress As New Compression.GZipStream( _
                  oStream, IO.Compression.CompressionMode.Compress)
                With oCompress
                    .Write(bBuffer, 0, bBuffer.Length)
                    .Flush()
                    .Close()
                End With
                oStream.Close()
            End If
        Catch ex As Exception
            'ERROR
        End Try
    End Sub

    Public Sub subUnzipFile(ByVal strZipFile As String, ByVal strDestFile As String)
        Try
            ' Existiert die Datei überhaupt
            If System.IO.File.Exists(strZipFile) Then
                ' GZIP-Datei öffnen
                Dim oStream As New FileStream(strZipFile, IO.FileMode.Open)
                Dim oCompress As New Compression.GZipStream( _
                  oStream, IO.Compression.CompressionMode.Decompress)

                ' Inhalt blockweise auslesen und dekomprimieren
                Dim bBuffer() As Byte
                Dim nOffset As Integer = 0
                Dim nCount As Integer = 0
                While True
                    ReDim Preserve bBuffer(nCount + 100)
                    Dim nBytes As Integer = oCompress.Read(bBuffer, nOffset, 100)
                    If nBytes = 0 Then Exit While
                    nOffset += nBytes
                    nCount += nBytes
                End While
                ReDim Preserve bBuffer(nCount - 1)

                ' Byte-Array in Zieldatei speichern
                My.Computer.FileSystem.WriteAllBytes(strDestFile, bBuffer, False)

                oStream.Close()
                oCompress.Close()
            End If
        Catch ex As Exception
            'ERROR
        End Try
    End Sub
End Class