Creating a zip file in memory

This topic demonstrates how to create a zip file in memory.

Basic steps

To create a zip file in memory, the following steps must be performed:

Retrieve a reference to a folder whose files will be added to the zip file using either the DiskFolder, ZippedFolder, ZipArchive, MemoryFolder or IsolatedFolder classes. With Xceed Zip for .NET, a folder is a folder; it does not matter if it is located within a zip file, on disk or in memory.
Retrieve a reference to a new or existing zip file using the ZipArchive class. Because we want the zip file to reside in memory, we will use a MemoryFile in the constructor of the ZipArchive class.
Call the CopyFilesTo method to copy the entire contents of the folder to the zip file.

Demonstration

This example demonstrates how to copy the contents of a folder located on disk to a zip file located in memory.

C#
VB.NET

public static void ZipIntoMemory()

{

  // Select a file that will be our zip file

  AbstractFile zipFile = new MemoryFile( "RAM_Disk", "CopyItemsToZip2.zip" );



  /* The component doesn't have distinct add and update operations.

     If you want any existing zip file to be overwritten, you need to delete the

     zip file before starting to perform any operation. */



  // If the zip file already exists

  if( zipFile.Exists )

    // Delete it

    zipFile.Delete();



  // Create a logical zip archive around the zip file

  ZipArchive zip = new ZipArchive( zipFile );



  // Wrap the operations that modify the zip archive in a batch update

  using( AutoBatchUpdate batch = new AutoBatchUpdate( zip ) )

  {

    // Select a source folder

    AbstractFile sourceFile = new DiskFile( @"D:\Data\File1.dat" );



    // Zip the files in the source folder into the zip archive

    sourceFile.CopyTo( zip, true );

  }



  /* To access the zipped data in memory, the application will open the

     zipped item for reading. Reading unzips data.

     Data will be read using a Stream object. Streaming allows data to be

     processed little by little, without having to create a large array to

     contain the entire data. */



  // Get the zipped item from the archive

  AbstractFile zippedFileInMemory = zip.GetFile( "File1.dat" );



  // Open the zipped item for reading

  using( Stream stream = zippedFileInMemory.OpenRead() )

  {

    // Create a read buffer

    int bufferLength = 8 * 1024;

    byte[] buffer = new byte[ bufferLength ];

    int read;



    // Attempt to unzip data

    read = stream.Read( buffer, 0, bufferLength );



    // While there is data to read

    while( read > 0 )

    {

      // TODO: Perform desired operation with the data read from the stream



      // Attempt to unzip more data

      read = stream.Read( buffer, 0, bufferLength );

    }

  }

}

    Public Shared Sub ZipIntoMemory()

      ' Select a file that will be our zip file

      Dim zipFile As AbstractFile = New MemoryFile("RAM_Disk", "CopyItemsToZip2.zip")



'       The component doesn't have distinct add and update operations.

'         If you want any existing zip file to be overwritten, you need to delete the

'         zip file before starting to perform any operation. 



      ' If the zip file already exists

      If zipFile.Exists Then

        ' Delete it

        zipFile.Delete()

      End If



      ' Create a logical zip archive around the zip file

      Dim zip As New ZipArchive(zipFile)



      ' Wrap the operations that modify the zip archive in a batch update

      Using batch As New AutoBatchUpdate(zip)

        ' Select a source folder

        Dim sourceFile As AbstractFile = New DiskFile("D:\Data\File1.dat")



        ' Zip the files in the source folder into the zip archive

        sourceFile.CopyTo(zip, True)

      End Using



'       To access the zipped data in memory, the application will open the

'         zipped item for reading. Reading unzips data.

'         Data will be read using a Stream object. Streaming allows data to be

'         processed little by little, without having to create a large array to

'         contain the entire data. 



      ' Get the zipped item from the archive

      Dim zippedFileInMemory As AbstractFile = zip.GetFile("File1.dat")



      ' Open the zipped item for reading

      Using stream As Stream = zippedFileInMemory.OpenRead()

        ' Create a read buffer

        Dim bufferLength As Integer = 8 * 1024

        Dim buffer(bufferLength - 1) As Byte

        Dim read As Integer



        ' Attempt to unzip data

        read = stream.Read(buffer, 0, bufferLength)



        ' While there is data to read

        Do While read > 0

          ' TODO: Perform desired operation with the data read from the stream



          ' Attempt to unzip more data

          read = stream.Read(buffer, 0, bufferLength)

        Loop

      End Using

    End Sub

Things you should consider

The main questions you should ask yourself when copying items to a zip file are:

Do you want to filter (specify specific files and folders) the items that are to be added to the zip file? Use filters.
Do you want to display the status of the operation? See the Events topic.
Do you want to add items into a specific folder within the zip file? Create an instance of a ZippedFolder object rather than a ZipArchive object.
Do you want to change the location of the temporary folder. Set the ZipArchive's TempFolder or DefaultTempFolder property.
Do you only want to copy a specific file or folder? Use the CopyTo method.
Do you want to move items rather than copy them? Use the MoveTo and MoveFilesTo methods.
Do you want to modify the default extra headers that are stored to a zip file? Set the ZipArchive's DefaultExtraHeaders property.

All zip files will automatically be created in the Zip64 zip file format if the limitations of the regular Zip format are reached.