Thursday, November 17, 2011

Easily zip / unzip files using Windows Shell32

Introduction

If you want to zip / unzip files without using third party libraries, and you want a method that can be used easily and works fine, you can use the Windows Shell32. I've written the code in VB 2010 using .NET Framework 2.0, but it's simple and can be easily converted to any other language like C#.

Using the Code

As I mentioned above, I'm going to use Visual Basic 2010 with .NET Framework 2.0.

  1. Create a new project.
  2. From the main menu, select Project -> Add Reference.
  3. Select the COM tab and search for Microsoft Shell Controls and Automation.

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How It Works

We will use the CopyHere command. We need to create an empty Zzip file, then we will use Shell32 to copy the files that we want to compress into the output Zip file. Or use it to unzip the files we have compressed previously to an output folder.

Imports Shell32   Public Class Form1       Sub Zip()         '1) Lets create an empty Zip File .         'The following data represents an empty zip file .          Dim startBuffer() As Byte = {80, 75, 5, 6, 0, 0, 0, 0, 0, 0, 0, _                                      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}          ' Data for an empty zip file .         FileIO.FileSystem.WriteAllBytes("d:\empty.zip", startBuffer, False)           'We have successfully made the empty zip file .          '2) Use the Shell32 to zip your files .         ' Declare new shell class         Dim sc As New Shell32.Shell()         'Declare the folder which contains the files you want to zip .         Dim input As Shell32.Folder = sc.NameSpace("D:\neededFiles")         'Declare  your created empty zip file as folder  .         Dim output As Shell32.Folder = sc.NameSpace("D:\empty.zip")         'Copy the files into the empty zip file using the CopyHere command .         output.CopyHere(input.Items, 4)       End Sub       Sub UnZip()         Dim sc As New Shell32.Shell()         'Declare the folder where the files will be extracted         Dim output As Shell32.Folder = sc.NameSpace("D:\extractedFiles")         'Declare your input zip file as folder  .         Dim input As Shell32.Folder = sc.NameSpace("d:\myzip.zip")         'Extract the files from the zip file using the CopyHere command .         output.CopyHere(input.Items, 4)       End Sub   End Class

In the CopyHere command, I have used option = 4. To use other options, please refer to this page:
http://msdn.microsoft.com/en-us/library/windows/desktop/bb787866(v=vs.85).aspx.

I hope I have provided something useful.

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