Writing zipped items using the Stream interface

When writing zipped items, it is sometimes useful to have a System.IO.Stream to give to other objects for them to write the data to be compressed. Classes outside of the application's own code will likely not know about ZipWriter and its WriteItemData() method.

The GetItemDataStream Method creates a write-only stream that calls WriteItemData() each time the stream's Write() method is called. This allows data to be fed to ZipWriter by objects that require a Stream object for output. The following example show how this can be used.

C#
VB.NET

static void Example()

{

  string zipFilePath = @"D:\RealTimeZipExamples\MyZipFile.zip";



  // Create a stream for a new zip file

  using( FileStream zipFileStream = new FileStream( zipFilePath, FileMode.Create, FileAccess.Write, FileShare.None ) )

  {

    // Create a ZipWriter instance that will write into a stream that has been prepared

    using( ZipWriter writer = new ZipWriter( zipFileStream ) )

    {

      ZipItemLocalHeader header = new ZipItemLocalHeader();



      header.FileName = "File1.xml";

      writer.WriteItemLocalHeader( header );



      // Instead of using WriteItemData(), we will get a writing stream to the item's data 

      using( Stream itemStream = writer.GetItemDataStream() )

      {

        // The stream will be 'closed' automatically by the 'using' statement. This will not 

        // close the zip file or the current item. It will only indicate to the stream 

        // that its work is done and clear its resources. 



        // Having a stream object handy here makes using a XmlWriter very easy 

        using( XmlWriter xml = XmlWriter.Create( itemStream ) )

        {

          xml.WriteStartDocument();

          xml.WriteStartElement( "SomeType" );

          xml.WriteElementString( "ID", "Something" );

          xml.WriteEndElement();

          xml.WriteEndDocument();

        }

      }



      header.FileName = "File2.xml";

      writer.WriteItemLocalHeader( header );

      using( Stream itemStream = writer.GetItemDataStream() )

      {

        using( XmlWriter xml = XmlWriter.Create( itemStream ) )

        {

          xml.WriteStartDocument();

          xml.WriteStartElement( "SomeOtherType" );



          byte[] someData = new byte[] { 12, 45, 67, 35, 67, 255, 255, 45 };



          // This is legal 

          writer.WriteItemData( someData );



          xml.WriteEndElement();

          xml.WriteEndDocument();

        }

      }



      byte[] someOtherData = new byte[] { 6, 34, 56, 108, 127, 98, 44, 35, 67, 255, 255, 45 };



      // This is also legal 

      writer.WriteItemData( someOtherData );

    }

  }

}

Private Shared Sub Example()

  Dim zipFilePath As String = "D:\RealTimeZipExamples\MyZipFile.zip"



  ' Create a stream for a new zip file

  Using zipFileStream As New FileStream(zipFilePath, FileMode.Create, FileAccess.Write, FileShare.None)

    ' Create a ZipWriter instance that will write into a stream that has been prepared

    Using writer As New ZipWriter(zipFileStream)

      Dim header As New ZipItemLocalHeader()



      header.FileName = "File1.xml"

      writer.WriteItemLocalHeader(header)



      ' Instead of using WriteItemData(), we will get a writing stream to the item's data 

      Using itemStream As Stream = writer.GetItemDataStream()

        ' The stream will be 'closed' automatically by the 'using' statement. This will not 

        ' close the zip file or the current item. It will only indicate to the stream 

        ' that its work is done and clear its resources. 



        ' Having a stream object handy here makes using a XmlWriter very easy 

        Using xml As XmlWriter = XmlWriter.Create(itemStream)

          xml.WriteStartDocument()

          xml.WriteStartElement("SomeType")

          xml.WriteElementString("ID", "Something")

          xml.WriteEndElement()

          xml.WriteEndDocument()

        End Using

      End Using



      header.FileName = "File2.xml"

      writer.WriteItemLocalHeader(header)

      Using itemStream As Stream = writer.GetItemDataStream()

        Using xml As XmlWriter = XmlWriter.Create(itemStream)

          xml.WriteStartDocument()

          xml.WriteStartElement("SomeOtherType")



          Dim someData() As Byte = {12, 45, 67, 35, 67, 255, 255, 45}



          ' This is legal 

          writer.WriteItemData(someData)



          xml.WriteEndElement()

          xml.WriteEndDocument()

        End Using

      End Using



      Dim someOtherData() As Byte = {6, 34, 56, 108, 127, 98, 44, 35, 67, 255, 255, 45}



      ' This is also legal 

      writer.WriteItemData(someOtherData)

    End Using

  End Using

End Sub