how to unzip files using external unzip software?

i have 50000 zip files.i need to unzip all those files and want to fetch .txt files alone from each zip files...any help..

Answer 1

[Friedrich]

Hi,

I would use JAVA to get what you want, e.g. the following example extract the .txt files in a zip files only (done with R2013b):

    zipFile = org.apache.tools.zip.ZipFile('Untitled1.zip');
    entries = zipFile.getEntries;
    while entries.hasMoreElements
         entry = entries.nextElement;
         entryName = char(entry.getName);
         [~,~,ext] = fileparts(entryName);
         if strcmp(ext,'.txt')
              inputStream  = zipFile.getInputStream(entry);
              fileOutputStream = java.io.FileOutputStream(fullfile(pwd,entryName));
              streamCopier = com.mathworks.mlwidgets.io.InterruptibleStreamCopier.getInterruptibleStreamCopier;
              streamCopier.copyStream(inputStream, fileOutputStream);
              fileOutputStream.close;
              inputStream.close;          
         end
    end
    zipFile.close

UPDATED VERSION FOR SCANNING A FOLDER FOR ZIP FILES AND PROCESS ALL OF THEM

zipfolder = 'C:\Users\fhempel\Desktop\tmp';
extractionfolder = 'C:\Users\fhempel\Desktop\tmp';

zipfiles = dir([zipfolder,'\*.zip']);

for i=1:numel(zipfiles)
    zipFile = org.apache.tools.zip.ZipFile(fullfile(zipfolder,zipfiles(i).name));
    entries = zipFile.getEntries;
    while entries.hasMoreElements
         entry = entries.nextElement;
         entryName = char(entry.getName);
         [~,~,ext] = fileparts(entryName);
         if strcmp(ext,'.txt')
              inputStream  = zipFile.getInputStream(entry);
              if ~exist(fullfile(extractionfolder,zipfiles(i).name(1:end-4)),'dir')
                  mkdir(fullfile(extractionfolder,zipfiles(i).name(1:end-4)))
              end
              fileOutputStream = java.io.FileOutputStream(fullfile(extractionfolder,zipfiles(i).name(1:end-4),entryName));
              streamCopier = com.mathworks.mlwidgets.io.InterruptibleStreamCopier.getInterruptibleStreamCopier;
              streamCopier.copyStream(inputStream, fileOutputStream);
              fileOutputStream.close;
              inputStream.close;          
         end
    end
    zipFile.close
end

[sandy]

thanks..it works..but this is for one zip file..but i need to do this for 50000 files in a loop..looping is possible in this java code?

[Friedrich]

Sure, do what Walter posted befrore. You do an outer loop around my code and it should work fine. You would also need to adjust the

org.apache.tools.zip.ZipFile('Untitled1.zip');

call and the

fileOutputStream = java.io.FileOutputStream(fullfile(pwd,entryName));

call accordingly. See my updated post above.

[sandy]

i am not familiar with java code...looping also different in java syntax,help file in matlab for java syntax is not sufficient for this i think

[sandy]

??? Improper index matrix
reference.

   Error in ==> zipfilecode at 6
    zipFile =
    org.apache.tools.zip.ZipFile(fullfile(zipfolder,zipfiles(i).name)); 
>>

[Friedrich]

The code works fine for me. From the error it seem that i is not what it is supposed to be. What value does the variable "i" have when the error occurs? And what dimensions has the variable "zipfiles"?

[sandy]

i=1 and i made some changes in the code in finding the .zip files using zipsearch() function as u can see below.my .zip files will be present inside many subfolders of a single main folder,so i used zipsearch(). also my output should be in a single folder where all .txt file should stored ther

zipfolder = 'C:\Users\fhempel\Desktop\tmp';
extractionfolder = 'C:\Users\fhempel\Desktop\tmp';
searchstr = '*.zip';
 zipfiles = zipsearch(zipfolder, searchstr);
for i=1:numel(zipfiles)
  zipFile = org.apache.tools.zip.ZipFile(fullfile(zipfolder,zipfiles(i).name));
  entries = zipFile.getEntries;
  while entries.hasMoreElements
       entry = entries.nextElement;
       entryName = char(entry.getName);
       [~,~,ext] = fileparts(entryName);
       if strcmp(ext,'.txt')
            inputStream  = zipFile.getInputStream(entry);
            if ~exist(fullfile(extractionfolder,zipfiles(i).name(1:end-4)),'dir')
                mkdir(fullfile(extractionfolder,zipfiles(i).name(1:end-4)))
            end
            fileOutputStream = java.io.FileOutputStream(fullfile(extractionfolder,zipfiles(i).name(1:end-4),entryName));
            streamCopier = com.mathworks.mlwidgets.io.InterruptibleStreamCopier.getInterruptibleStreamCopier;
            streamCopier.copyStream(inputStream, fileOutputStream);
            fileOutputStream.close;
            inputStream.close;          
       end
  end
  zipFile.close
end

[Friedrich]

I dont know the zipsearch functon and I dont know what it returns. But you need to adjust this line

zipFile = org.apache.tools.zip.ZipFile(fullfile(zipfolder,zipfiles(i).name));

Basically the argument needs to be the absolut path to the zip file you like to process, e.g. C:\some_folder\myzip.zip.

Since the output should be in one folder you can remove this three lines:

   if ~exist(fullfile(extractionfolder,zipfiles(i).name(1:end-4)),'dir')
                  mkdir(fullfile(extractionfolder,zipfiles(i).name(1:end-4)))
              end

Finally this one needs to be adjusted:

fileOutputStream = java.io.FileOutputStream(fullfile(extractionfolder,zipfiles(i).name(1:end-4),entryName));

I guess it should be:

fileOutputStream = java.io.FileOutputStream(fullfile(extractionfolder,entryName));

Please also update the extractionfolder variable to an existing folder on your machine. In addition please also update the zipfolder variable accordingly.

[Arjun Ajit Kottara]

Hey, I was searching for this answer!, but I need to just extract the multiple zip files to another targer folder, so what changes should I make? since this will filter out non .txt files..

Answer 2

[Walter Roberson]

http://matlab.wikia.com/wiki/FAQ#How_can_I_process_a_sequence_of_files.3F

[sandy]

thanks...this s for fetching files in a dir or a specific folder..fetching inside each zip file is difficult here.any ideas..also.matlab unzip() function is faster than external program zip.exe ?..suggestion

Answer 3

[Peng Zheng]

Hello, I think this answer is very useful for me.But I don't understand this two lines:

 streamCopier = com.mathworks.mlwidgets.io.InterruptibleStreamCopier.getInterruptibleStreamCopier;

 streamCopier.copyStream(inputStream, fileOutputStream);

Can you please be so kind to tell me what does this mean and what it will return?