Read files in zip file without unzipping

Hi there

I have a zip file with about 100 binary files in. I have a routine to read the files into matlab variables. Is there a way that I can read the files directly without unpacking the zip file?

Thanks in advance.

Etienne

[Jan]

What do you want to do with a zipped variable? Do you want to unzip one of the files only?

Answer 1

[Bob Hamans]

Hi Etienne. I don't know if I understand your question but you just want to list the zip file contents without unzipping? The following code does just that:

function filelist = listzipcontents(zipFilename)
% Create a Java file of the ZIP filename.
zipJavaFile  = java.io.File(zipFilename);
% Create a Java ZipFile and validate it.
zipFile = org.apache.tools.zip.ZipFile(zipJavaFile);
% Extract the entries from the ZipFile.
entries = zipFile.getEntries;

% Initialize the file list.
filelist={};

% Loop through the entries and add to the file list.
while entries.hasMoreElements
    filelist = cat(1,filelist,char(entries.nextElement));
end
end

[Bob Hamans]

I added some documentation and submitted the function to the File Exchange

[Ashish Uthama]

[Move as comment - AU]

Hi Bob

I actualy meant that I would like to read the contents of the files directly without having to unzip the file. It is easy enough to unzip and zip the files. I just wanted to see if there is an alternative.

Regards

Etienne

[Oleg Komarov]

The comment is ambiguous but the code does list the content WITHOUT unzipping.

In other words:

 entries = zipFile.getEntries;

does not unzip the content.

The submission can be found on http://www.mathworks.co.uk/matlabcentral/fileexchange/32089-listzipcontents and this should be included with unzip() as an enhancement.

[Lars Janssen]

For those using the code snippet above, please add:

zipFile.close

This will "unlock" the java file again. After having some trouble deleting the zip file I found this missing piece of code here:Extracting specific file from zip in matlab - Stack Overflow.

[Mark Gugliuzza]

Does anyone know if it is possible to perform this recursively? I have zips within zips that I need to read all the file names out of?

Answer 2

[Etienne Coetzee]

Ok, thanks Robert. I will log it as an enhancement.

Answer 3

[Robert Cumming]

have you seen this thread - you could try what it suggests in your own copy of unzip.m - or send an enhancement request to Mathworks.

Its actually quite easy to update the m file(s):

1. Change the number of accepted input arguments to 3.
2. Handle the third input agument (say a cell array of requested files) or set to default (empty cell array)
3. Pass the 3rd argument into the private function extractArchive  
4. In the private function do a strcmp on the entryName and your cell array of requested file(s) - if match found extract, if not skip to next (use continue in the while loop)

Answer 4

[Brunno Machado de Campos]

Hi, If anyone is until interested, for zip, on Windows (where I tested):

a = fopen('ZIPFILENAME.zip','r');
c2 = fread(a,'uint8=>uint8');
zipname = char(c2(31:31+c2(27)-1));
zipname = strcat(zipname')

[Chris Piker]

I like it. Thanks! I'll look into the zip binary format a bit more.

[Collin Pecora]

https://www.mathworks.com/matlabcentral/fileexchange/77257-zipfile

Allows for extracting specific file from a zip archive.