Imports System

Imports System.IO

Imports Xceed.Zip.ReaderWriter

Namespace RealTimeZipExamples

  Friend Class Examples

    Public Shared Sub TheZipReaderClass()

      ' Pick a zip file

      Dim zipFileName As String = "D:\SomeFolder\SomeZipFile.zip"

      ' Pick a base output folder, taking care not to end it with a directory separator

      Dim unzipToFolder As String = "D:\SomeOtherFolder"

      ' Open the source Zip file

      Using zipFileStream As New FileStream(zipFileName, FileMode.Open, FileAccess.Read)

        ' Create a Zip reader object around the stream.

        ' Remember that ZipReader doesn't close the underlying stream given here

        Using zipReader As New ZipReader(zipFileStream)

          ' Optional. Provide the default password for encrypted items in the archive

          zipReader.EncryptionPassword = "Password"

          ' Optional. Subscribe to available events

          AddHandler zipReader.ByteProgression, AddressOf OnByteProgression

          AddHandler zipReader.InvalidPassword, AddressOf OnInvalidPassword

          Dim zipItemLocalHeader As ZipItemLocalHeader

          ' While the reader finds local headers

          zipItemLocalHeader = zipReader.ReadItemLocalHeader()

          Do While zipItemLocalHeader IsNot Nothing

            ' The 'FileName' property contains the sub-folders and filename

            Dim outputPath As String = unzipToFolder & zipItemLocalHeader.FileName

            Dim outputFolder As String = Path.GetDirectoryName(outputPath)

            ' Make sure the output folder exists

            Directory.CreateDirectory(outputFolder)

            ' If the item isn't a folder entry

            If (Not zipItemLocalHeader.IsFolder) Then

              ' Create/overwrite an output file using our calculated filename

              Using outputFileStream As New FileStream(outputPath, FileMode.Create, FileAccess.Write)

                ' Have the reader read the item data and write it to the stream using a 64K buffer

                zipReader.ReadItemData(outputFileStream, 64 * 1024)

              End Using

            End If

              zipItemLocalHeader = zipReader.ReadItemLocalHeader()

          Loop

          ' Optional. Have the reader give us the zip ending header

          Dim endHeader As ZipEndHeader = zipReader.ReadEndHeader()

          ' If the header contains a global zip comment

          If endHeader IsNot Nothing AndAlso (Not String.IsNullOrEmpty(endHeader.ZipComment)) Then

            ' TODO: Do something with the global zip comment

          End If

        End Using

      End Using

    End Sub

    Private Shared Sub OnInvalidPassword(ByVal sender As Object, ByVal e As ZipReaderInvalidPasswordEventArgs)

      ' TODO: We have access to the current item being unzipped. We can report it's name, etc

      Dim currentItem As ZipItemLocalHeader = e.ZipItemLocalHeader

      ' TODO: We're given the password that failed. We can report it, etc

      Dim oldPassword As String = e.OldPassword

'      If 'e.NewPassword' is set to null or an empty string, or 'e.Abort' is set to true,

'      a ZipReaderException will be thrown for failure to decrypt the item.

'      Since items can't be skipped, the entire unzip process will be canceled.

'       

'      When the event is triggered, 'e.NewPassword' is set to an empty string and 'e.Abort' is set

'      to false.

      ' TODO: We have to supply a new password.

      ' If that new password is invalid, the event will be triggered again

      e.NewPassword = "Some New Password"

      ' TODO: We can ask the entire unzip operation to be aborted

      e.Abort = True

    End Sub

    Private Shared Sub OnByteProgression(ByVal sender As Object, ByVal e As ZipReaderByteProgressionEventArgs)

      ' TODO: We have access to the current item being unzipped. We can report it's name, etc

      Dim currentItem As ZipItemLocalHeader = e.ZipItemLocalHeader

      ' TODO: We're given the current amount of bytes unzipped for the item. We can report it, etc

      Dim bytesProcessed As Long = e.BytesProcessed

'      Do not assume that e.UncompressedSize and e.Percent will contain useful values.

'      Since ZipReader doesn't seek in the archive, it cannot always know the uncompressed

'      size in advance.

    End Sub

  End Class

End Namespace