7zip extract specific files

import com.aimms.pro.exceptions.ExtractionException;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.io.RandomAccessFile;
import java.util.ArrayList;
import java.util.List;

import net.sf.sevenzipjbinding.ExtractAskMode;
import net.sf.sevenzipjbinding.ExtractOperationResult;
import net.sf.sevenzipjbinding.IArchiveExtractCallback;
import net.sf.sevenzipjbinding.ISequentialOutStream;
import net.sf.sevenzipjbinding.ISevenZipInArchive;
import net.sf.sevenzipjbinding.PropID;
import net.sf.sevenzipjbinding.SevenZip;
import net.sf.sevenzipjbinding.SevenZipException;
import net.sf.sevenzipjbinding.impl.RandomAccessFileInStream;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Class taken from https://gist.github.com/borisbrodski/6120309
 *
 * @author Horia
 */
public class ArchiveExtractorHelper {

    private final Logger LOG = LoggerFactory.getLogger(getClass());

    class ExtractCallback implements IArchiveExtractCallback {

        private ISevenZipInArchive inArchive;
        private int index;
        private Boolean skipExtraction;
        private OutputStream outputStream;
        private File file;

        ExtractCallback(ISevenZipInArchive inArchive) {
            this.inArchive = inArchive;
        }

        @Override
        public void setTotal(long total) throws SevenZipException {
        }

        @Override
        public void setCompleted(long completeValue) throws SevenZipException {
        }

        @Override
        public ISequentialOutStream getStream(int index,
                ExtractAskMode extractAskMode) throws SevenZipException {

            closeOutputStream();

            this.index = index;
            skipExtraction = (Boolean) inArchive.getProperty(index, PropID.IS_FOLDER);
            String path = (String) inArchive.getProperty(index, PropID.PATH);
            file = new File(outputDirectoryFile, path);
            if (extractAskMode != ExtractAskMode.EXTRACT) {
                if (skipExtraction) {
                    createDirectory(file);
                }
                return null;
            }

            createDirectory(file.getParentFile());

            try {
                outputStream = new FileOutputStream(file);
            } catch (FileNotFoundException e) {
                throw new SevenZipException("Error opening file: "
                        + file.getAbsolutePath(), e);
            }

            return new ISequentialOutStream() {
                @Override
                public int write(byte[] data) throws SevenZipException {
                    try {
                        outputStream.write(data);
                    } catch (IOException e) {
                        throw new SevenZipException("Error writing to file: "
                                + file.getAbsolutePath());
                    }
                    return data.length; // Return amount of proceed data
                }
            };
        }

        private void createDirectory(File parentFile) throws SevenZipException {
            if (!parentFile.exists()) {
                if (!parentFile.mkdirs()) {
                    throw new SevenZipException("Error creating directory: "
                            + parentFile.getAbsolutePath());
                }
            }
        }

        private void closeOutputStream() throws SevenZipException {
            if (outputStream != null) {
                try {
                    outputStream.close();
                } catch (IOException e) {
                    throw new SevenZipException("Error closing file: "
                            + file.getAbsolutePath());
                }
            }
        }

        @Override
        public void prepareOperation(ExtractAskMode extractAskMode)
                throws SevenZipException {
        }

        @Override
        public void setOperationResult(
                ExtractOperationResult extractOperationResult)
                throws SevenZipException {
            if (skipExtraction) {
                return;
            }
            if (extractOperationResult != ExtractOperationResult.OK) {
                String path = (String) inArchive.getProperty(index, PropID.PATH);
                throw new SevenZipException("Extraction error: " + path);
            } else {
            }
        }
    }
    private File archive;
    private String outputDirectory;
    private File outputDirectoryFile;

    public ArchiveExtractorHelper(File archive, String outputDirectory) {
        this.archive = archive;
        this.outputDirectory = outputDirectory;
    }

    public void extract(String... fileNames) throws ExtractionException {
        checkArchiveFile();
        prepareOutputDirectory();
        extractAllArchive(fileNames);
    }

    private void prepareOutputDirectory() throws ExtractionException {
        outputDirectoryFile = new File(outputDirectory);
        if (!outputDirectoryFile.exists()) {
            outputDirectoryFile.mkdirs();
        } else {
            if (outputDirectoryFile.list().length != 0) {
                LOG.info("Output directory not empty: "
                        + outputDirectory);
            }
        }
    }

    private void checkArchiveFile() throws ExtractionException {
        if (!archive.exists()) {
            throw new ExtractionException("Archive file not found: " + archive);
        }
        if (!archive.canRead()) {
            throw new ExtractionException("Can't read archive file: {}" + archive);
        }
    }

    private void extractAllArchive(String... files) throws ExtractionException {
        try (RandomAccessFile randomAccessFile = new RandomAccessFile(archive, "r")) {
            extractArchive(randomAccessFile, files);
            LOG.trace("succesfully extracted archive to {}", archive);
        } catch (FileNotFoundException e) {
            throw new ExtractionException("File not found", e);
        } catch (IOException e) {
            throw new ExtractionException("Error closing archive file", e);
        }
    }

    private int[] transformFileNamesToIndexes(ISevenZipInArchive inArchive, String... fileNames) throws SevenZipException {
        int[] filesToExtract = null;
        if (fileNames == null || fileNames.length == 0) {
            return filesToExtract;
        }
        int count = inArchive.getNumberOfItems();
        List<Integer> itemsToExtract = new ArrayList<>();
        for (String fileName : fileNames) {
            for (int index = 0; index < count; index++) {
                if (!((Boolean) inArchive.getProperty(index, PropID.IS_FOLDER)).booleanValue()) {
                    if (fileName.equals(inArchive.getProperty(index, PropID.PATH))) {
                        itemsToExtract.add(index);
                        break;
                    }
                }
            }
        }
        int index = 0;
        filesToExtract = new int[itemsToExtract.size()];
        for (Integer integer : itemsToExtract) {
            filesToExtract[index++] = integer.intValue();
        }
        return filesToExtract;
    }

    private void extractArchive(RandomAccessFile file, String... fileNames) throws ExtractionException {
        ISevenZipInArchive inArchive;
        boolean ok = false;
        int[] filesToExtract;
        try {
            inArchive = SevenZip.openInArchive(null, new RandomAccessFileInStream(file));
            filesToExtract = transformFileNamesToIndexes(inArchive, fileNames);
        } catch (SevenZipException e) {
            throw new ExtractionException("Error opening archive", e);
        }
        try {
            inArchive.extract(filesToExtract, false, new ExtractCallback(inArchive));
            ok = true;
        } catch (SevenZipException e) {
            StringBuilder stringBuilder = new StringBuilder();
            stringBuilder.append("Error extracting archive '");
            stringBuilder.append(archive);
            stringBuilder.append("': ");
            stringBuilder.append(e.getMessage());
            if (e.getCause() != null) {
                stringBuilder.append(" (");
                stringBuilder.append(e.getCause().getMessage());
                stringBuilder.append(')');
            }
            throw new ExtractionException(stringBuilder.toString(), e);
        } finally {
            try {
                inArchive.close();
            } catch (SevenZipException e) {
                if (ok) {
                    throw new ExtractionException("Error closing archive", e);
                }
            }
        }
    }
}