I looked at the default Zip library that comes with the JDK and the Apache compression libs and I am unhappy with them for 3 reasons:
They are bloated and have bad API design. I have to write 50 lines of boiler plate byte array output, zip input, file out streams and close relevant streams and catch exceptions and move byte buffers on my own? Why can't I have a simple API that looks like this Zipper.unzip(InputStream zipFile, File targetDirectory, String password = null) and Zipper.zip(File targetDirectory, String password = null) that just works?
It seems zipping unzipping destroys file meta-data and password handling is broken.
Also, all the libraries I tried were 2-3x slow compared to the command line zip tools I get with UNIX?
For me (2) and (3) are minor points but I really want a good tested library with a one-line interface.
I know its late and there are lots of answers but this zip4j is one of the best libraries for zipping I have used. Its simple (no boiler code) and can easily handle password protected files.
import net.lingala.zip4j.exception.ZipException;
import net.lingala.zip4j.core.ZipFile;
public static void unzip(){
String source = "some/compressed/file.zip";
String destination = "some/destination/folder";
String password = "password";
try {
ZipFile zipFile = new ZipFile(source);
if (zipFile.isEncrypted()) {
zipFile.setPassword(password);
}
zipFile.extractAll(destination);
} catch (ZipException e) {
e.printStackTrace();
}
}
The Maven dependency is:
<dependency>
<groupId>net.lingala.zip4j</groupId>
<artifactId>zip4j</artifactId>
<version>1.3.2</version>
</dependency>
In Java 8, with Apache Commons-IO's IOUtils you can do this:
try (java.util.zip.ZipFile zipFile = new ZipFile(file)) {
Enumeration<? extends ZipEntry> entries = zipFile.entries();
while (entries.hasMoreElements()) {
ZipEntry entry = entries.nextElement();
File entryDestination = new File(outputDir, entry.getName());
if (entry.isDirectory()) {
entryDestination.mkdirs();
} else {
entryDestination.getParentFile().mkdirs();
try (InputStream in = zipFile.getInputStream(entry);
OutputStream out = new FileOutputStream(entryDestination)) {
IOUtils.copy(in, out);
}
}
}
}
It's still some boilerplate code, but it has only 1 non-exotic dependency: Commons-IO
In Java 11 and higher, better options might be available, see ZhekaKozlov's comment.
Extract zip file and all its subfolders, using only the JDK:
private void extractFolder(String zipFile,String extractFolder)
{
try
{
int BUFFER = 2048;
File file = new File(zipFile);
ZipFile zip = new ZipFile(file);
String newPath = extractFolder;
new File(newPath).mkdir();
Enumeration zipFileEntries = zip.entries();
// Process each entry
while (zipFileEntries.hasMoreElements())
{
// grab a zip file entry
ZipEntry entry = (ZipEntry) zipFileEntries.nextElement();
String currentEntry = entry.getName();
File destFile = new File(newPath, currentEntry);
//destFile = new File(newPath, destFile.getName());
File destinationParent = destFile.getParentFile();
// create the parent directory structure if needed
destinationParent.mkdirs();
if (!entry.isDirectory())
{
BufferedInputStream is = new BufferedInputStream(zip
.getInputStream(entry));
int currentByte;
// establish buffer for writing file
byte data[] = new byte[BUFFER];
// write the current file to disk
FileOutputStream fos = new FileOutputStream(destFile);
BufferedOutputStream dest = new BufferedOutputStream(fos,
BUFFER);
// read and write until last byte is encountered
while ((currentByte = is.read(data, 0, BUFFER)) != -1) {
dest.write(data, 0, currentByte);
}
dest.flush();
dest.close();
is.close();
}
}
}
catch (Exception e)
{
Log("ERROR: "+e.getMessage());
}
}
Zip files and all its subfolders:
private void addFolderToZip(File folder, ZipOutputStream zip, String baseName) throws IOException {
File[] files = folder.listFiles();
for (File file : files) {
if (file.isDirectory()) {
addFolderToZip(file, zip, baseName);
} else {
String name = file.getAbsolutePath().substring(baseName.length());
ZipEntry zipEntry = new ZipEntry(name);
zip.putNextEntry(zipEntry);
IOUtils.copy(new FileInputStream(file), zip);
zip.closeEntry();
}
}
}