Apache Commons Compress - De Compress Zip File

[Ron Ingram]

I'm trying to decompress a zip archive with a sub-directory using apache commons and commons compress. It runs with no errors, however, the files appear as folders and are empty. Not sure what is causing this...

/*
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 * and open the template in the editor.
 */
package unziptest;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import org.apache.commons.compress.archivers.ArchiveException;
import org.apache.commons.compress.archivers.ArchiveInputStream;
import org.apache.commons.compress.archivers.ArchiveStreamFactory;
import org.apache.commons.compress.archivers.zip.ZipArchiveEntry;
import org.apache.commons.io.FileUtils;

public class UnZip {

    //final String OUTPUT_FOLDER = "C:\\Users\\Ronald\\Documents\\TestZip\\";
    final String OUTPUT_FOLDER = "dest";

    public void unzip(String file) throws FileNotFoundException, IOException, ArchiveException {

        File inputFile = new File(file);

        InputStream is = new FileInputStream(inputFile);
        ArchiveInputStream ais = new ArchiveStreamFactory().createArchiveInputStream("zip", is);

        ZipArchiveEntry entry = null;


        while ((entry = (ZipArchiveEntry) ais.getNextEntry()) != null) {
            File outFile = new File(OUTPUT_FOLDER + File.separator + entry.getName());
            if (!outFile.exists()) {
                outFile.mkdirs();
                continue;
            }
            if (outFile.isDirectory()) {
                continue;
            }

            if (outFile.exists()) {
                continue;
            }

            FileUtils.copyInputStreamToFile(ais, outFile);

        }

    }
}

[Paul Clapham]

Ron Ingram wrote:the files appear as folders

Because your code at lines 35 and 36 does that.

[Ron Ingram]

Agree.. but now it is not iterating in the while loop. the entry = (ZipArchiveEntry) ais.getNextEntry() return null for any new file. It only seems to iterate once correctly writing the file.

new method..

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */
package unziptest;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.util.zip.ZipEntry;
import org.apache.commons.compress.archivers.ArchiveException;
import org.apache.commons.compress.archivers.ArchiveInputStream;
import org.apache.commons.compress.archivers.ArchiveStreamFactory;
import org.apache.commons.compress.archivers.zip.ZipArchiveEntry;
import org.apache.commons.io.FileUtils;

public class UnZip {

    //final String OUTPUT_FOLDER = "C:\\Users\\Ronald\\Documents\\TestZip\\";
    final String OUTPUT_FOLDER = "dest";

    public void unzip(String file) throws FileNotFoundException, IOException, ArchiveException {

        File inputFile = new File(file);

        InputStream is = new FileInputStream(inputFile);
        ArchiveInputStream ais = new ArchiveStreamFactory().createArchiveInputStream("zip", is);
        ZipEntry entry = (ZipArchiveEntry) ais.getNextEntry();

        while (entry != null) {

            if (entry.getName().endsWith("/")) {
                File dir = new File(OUTPUT_FOLDER + File.separator + entry.getName());
                if (!dir.exists()) {
                    dir.mkdirs();
                }
                entry = (ZipArchiveEntry) ais.getNextEntry();
                continue;
            }

            File outFile = new File(OUTPUT_FOLDER + File.separator + entry.getName());

            if (outFile.isDirectory()) {
                entry = (ZipArchiveEntry) ais.getNextEntry();
                continue;
            }

            if (outFile.exists()) {
                entry = (ZipArchiveEntry) ais.getNextEntry();
                continue;
            }
            
            
            System.out.println("sending ");
            FileUtils.copyInputStreamToFile(ais, outFile);
            entry = (ZipArchiveEntry) ais.getNextEntry();
            
            



        }
    }
}

[Ron Ingram]

Finally got it working. Apache Commons FileUtils and IOUtils seem to break the loop.

Changed to FileOutputStream

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */
package unziptest;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.zip.ZipEntry;
import org.apache.commons.compress.archivers.ArchiveException;
import org.apache.commons.compress.archivers.ArchiveInputStream;
import org.apache.commons.compress.archivers.ArchiveStreamFactory;
import org.apache.commons.compress.archivers.zip.ZipArchiveEntry;

public class UnZip {

    final String OUTPUT_FOLDER = "dest";

    public void unzip(String file) throws FileNotFoundException, IOException, ArchiveException {

        File inputFile = new File(file);

        InputStream is = new FileInputStream(inputFile);
        ArchiveInputStream ais = new ArchiveStreamFactory().createArchiveInputStream("zip", is);
        ZipEntry entry = null;

        while ((entry = (ZipArchiveEntry) ais.getNextEntry()) != null) {

            if (entry.getName().endsWith("/")) {
                File dir = new File(OUTPUT_FOLDER + File.separator + entry.getName());
                if (!dir.exists()) {
                    dir.mkdirs();
                }
                continue;
            }

            File outFile = new File(OUTPUT_FOLDER + File.separator + entry.getName());

            if (outFile.isDirectory()) {
                continue;
            }

            if (outFile.exists()) {
                continue;
            }

            FileOutputStream out = new FileOutputStream(outFile);
            byte[] buffer = new byte[1024];
            int length = 0;
            while ((length = ais.read(buffer)) > 0) {
                out.write(buffer, 0, length);
                out.flush();
            }

        }
    }
}

[Rob Spoor]

You should close your FileOutputStreams, as well as your ArchiveInputStream, preferably in try-finally blocks or try-with-resources. Right now you have a major resource leak, and if your archive contains too many entries you will run out of file handles.

I think the issue with your original code is that FileUtils.copyInputStreamToFile closes the source input stream. I think this is a mistake, because a) it's not documented, and b) library calls shouldn't close resources that are passed as input arguments - it's the responsibility of the code that created a resource to close it again.

Anyway, your original code would work if you'd wrap the ArchiveInputStream in an CloseShieldInputStream. The resulting InputStream behaves just like the wrapped ArchiveInputStream except its close() method does nothing. As a result, FileUtils.copyInputStreamToFile would still do the correct copying but it wouldn't close your ArchiveInputStream.