import java.io.*;
import java.util.zip.ZipEntry;
import java.util.zip.ZipInputStream;

/**
 * This utility extracts files and directories of a standard zip file to
 * a destination directory.
 *
 * @author www.codejava.net
 */
public class UnzipUtility {
    /**
     * Size of the buffer to read/write data
     */
    private static final int BUFFER_SIZE = 4096;

    /**
     * Extracts a zip file specified by the zipFilePath to a directory specified by
     * destDirectory (will be created if does not exists)
     *
     * @param zipFilePath   path of the archive
     * @param destDirectory where to extract to
     * @throws IOException
     */
    public void unzip(String zipFilePath, String destDirectory) throws IOException {
        File destDir = new File(destDirectory);
        if (!destDir.exists()) {
            if (!destDir.mkdir())
                throw new IOException("Unable to create a root directory to unzip the archive");
        }
        ZipInputStream zipIn = new ZipInputStream(new FileInputStream(zipFilePath));
        ZipEntry entry = zipIn.getNextEntry();
        // iterates over entries in the zip file
        while (entry != null) {
            String filePath = destDirectory + File.separator + entry.getName();
            if (!entry.isDirectory()) {
                // if the entry is a file, extracts it
                extractFile(zipIn, filePath);
            } else {
                // if the entry is a directory, make the directory
                File dir = new File(filePath);

                if (!dir.mkdir()) {
                    throw new IOException("Unable to create a directory to unzip the directory");
                }
            }
            zipIn.closeEntry();
            entry = zipIn.getNextEntry();
        }
        zipIn.close();
    }

    /**
     * Extracts a zip entry (file entry)
     *
     * @param zipIn    ZipInputStream
     * @param filePath Where to extract to
     * @throws IOException
     */
    private void extractFile(ZipInputStream zipIn, String filePath) throws IOException {
        BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(filePath));
        byte[] bytesIn = new byte[BUFFER_SIZE];
        int read;
        while ((read = zipIn.read(bytesIn)) != -1) {
            bos.write(bytesIn, 0, read);
        }
        bos.close();
    }
}