Scompattare archivi con java.util.zip

Riporto una classe molto utile per effettuare estrazioni di archivi in formato ZIP e GZIP compressi su algoritmo deflate. L’operazione di estrazione usa l’utility java.util.zip presente all’interno della libreria nativa rt.jar di JDK. Per aumentare le performance sulle operazioni di I/O sui file, vengono utilizzati gli oggetti java.io.BufferedInputStream e java.io.BufferedOutputStream.

package eu.giuseppeurso.utils;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.Enumeration;
import java.util.zip.ZipEntry;
import java.util.zip.ZipFile;

public class ZipUtils {
	public static void unzip(String strZipFile) {
		try {

			File fSourceZip = new File(strZipFile);
			String zipPath = strZipFile.substring(0, strZipFile.length() - 4);
			File temp = new File(zipPath);
			temp.mkdir();
			System.out.println(zipPath + " created");

			ZipFile zipFile = new ZipFile(fSourceZip);
			Enumeration<?> e = zipFile.entries();

			while (e.hasMoreElements()) {
				ZipEntry entry = (ZipEntry) e.nextElement();
				File destinationFilePath = new File(zipPath, entry.getName());

				destinationFilePath.getParentFile().mkdirs();

				if (entry.isDirectory()) {
					continue;
				} else {
					System.out.println("Extracting " + destinationFilePath);
					BufferedInputStream bis = new BufferedInputStream(zipFile.getInputStream(entry));

					int b;
					byte buffer[] = new byte[1024];

					FileOutputStream fos = new FileOutputStream(destinationFilePath);
					BufferedOutputStream bos = new BufferedOutputStream(fos,1024);

					while ((b = bis.read(buffer, 0, 1024)) != -1) {
						bos.write(buffer, 0, b);
					}

					// flush the output stream and close it.
					bos.flush();
					bos.close();

					// close the input stream.
					bis.close();
				}
			}
		} catch (IOException ioe) {
			System.out.println("IOError :" + ioe);
		}

	}
}