Zip4j

Zip4j is a comprehensive Java library designed to simplify working with zip files and streams. It aims to reduce boilerplate code compared to Java's built-in zip support by handling the heavy lifting of stream management and complex zip operations.

Key features include:

• File Operations: Create, Add, Extract, Update, and Remove files from a zip file.
• Stream Support: Support for ZipInputStream and ZipOutputStream.
• Encryption: Read/Write password-protected zip files and streams using both AES and standard zip encryption methods.
• Format Support: Support for Zip64 format and split zip files (e.g., .z01, .z02, ..., .zip).
• Compression: Support for both Store (no compression) and Deflate compression methods.
• Unicode: Support for Unicode file names and comments.
• Progress Monitoring: Includes a Progress Monitor for integration into user-facing applications.

Zip4j uses the Deflate algorithm by default. You can change this using ZipParameters.

Using STORE (no compression):

ZipParameters zipParameters = new ZipParameters();
zipParameters.setCompressionMethod(CompressionMethod.STORE);
new ZipFile("filename.zip").addFile("fileToAdd", zipParameters);

AES Encryption: To protect files with AES encryption, set the encryption method and key strength. AES 256 is the default.

ZipParameters zipParameters = new ZipParameters();
zipParameters.setEncryptFiles(true);
zipParameters.setEncryptionMethod(EncryptionMethod.AES);
zipParameters.setAesKeyStrength(AesKeyStrength.KEY_STRENGTH_256); 

List<File> filesToAdd = Arrays.asList(new File("somefile"), new File("someotherfile"));
ZipFile zipFile = new ZipFile("filename.zip", "password".toCharArray());
zipFile.addFiles(filesToAdd, zipParameters);

Zip Standard Encryption: Replace the AES method with EncryptionMethod.ZIP_STANDARD.

zipParameters.setEncryptionMethod(EncryptionMethod.ZIP_STANDARD);

To integrate progress tracking (e.g., for progress bars) in user-facing applications, use the ProgressMonitor.

1. Call ZipFile.setRunInThread(true) to ensure zip operations run in a background thread.
2. Retrieve the monitor via ZipFile.getProgressMonitor().
3. The operation (like addFolder, addFiles, removeFiles, or extractFiles) will return control to the caller immediately.
4. Poll the monitor in a loop until progressMonitor.getState() returns ProgressMonitor.State.READY.

Available information from the monitor:

• getPercentDone(): Percentage of work completed.
• getFileName(): The current file being processed.
• getCurrentTask(): The current action being performed.
• getResult(): Returns SUCCESS, ERROR, or CANCELLED once finished.
• getException(): Returns the exception if the result is ERROR.

ZipFile zipFile = new ZipFile(generatedZipFile, PASSWORD);
ProgressMonitor progressMonitor = zipFile.getProgressMonitor();

zipFile.setRunInThread(true);
zipFile.addFolder(new File("/some/folder"));

while (!progressMonitor.getState().equals(ProgressMonitor.State.READY)) {
  System.out.println("Percentage done: " + progressMonitor.getPercentDone());
  System.out.println("Current file: " + progressMonitor.getFileName());
  System.out.println("Current task: " + progressMonitor.getCurrentTask());

  Thread.sleep(100);
}

if (progressMonitor.getResult().equals(ProgressMonitor.Result.SUCCESS)) {
  System.out.println("Successfully added folder to zip");
} else if (progressMonitor.getResult().equals(ProgressMonitor.Result.ERROR)) {
  System.out.println("Error occurred. Error message: " + progressMonitor.getException().getMessage());
} else if (progressMonitor.getResult().equals(ProgressMonitor.Result.CANCELLED)) {
  System.out.println("Task cancelled");
}

Zip4j provides several ways to extract content from an archive.

Extract all files:

new ZipFile("filename.zip").extractAll("/destination_directory");

Extract a single file:

new ZipFile("filename.zip").extractFile("fileNameInZip.txt", "/destination_directory");

Extract a folder (since v2.6.0): If the filename represents a directory, all files within that directory will be extracted.

new ZipFile("filename.zip").extractFile("folderNameInZip/", "/destination_directory");

Extract with a new filename: You can rename the file during extraction by providing a third parameter.

new ZipFile("filename.zip").extractFile("fileNameInZip.txt", "/destination_directory", "newfileName.txt");

Extracting password protected files: Pass the password as a char[] to the ZipFile constructor.

new ZipFile("filename.zip", "password".toCharArray()).extractAll("/destination_directory");

Zip4j allows renaming individual files, multiple files, or entire directories.

Rename a single file:

new ZipFile("filename.zip").renameFile("old-name.pdf", "new-name.pdf");

Rename multiple files: Use a Map<String, String> where the key is the current name and the value is the new name.

Map<String, String> fileNamesMap = new HashMap<>();
fileNamesMap.put("firstFile.txt", "newFileFirst.txt");
new ZipFile("filename.zip").renameFiles(fileNamesMap);

Moving an entry: To move an entry to a different folder, include the new path in the new name. If you omit the parent path in the new name, the file will be moved to the root of the zip.

// Moves and renames
new ZipFile("filename.zip").renameFile("some-folder/old.pdf", "new-folder/new.pdf");

// Moves to root
new ZipFile("filename.zip").renameFile("some-folder/old.pdf", "new.pdf");

Note: Renaming is not supported for split zip files.

new ZipFile("filename.zip").renameFile("entry-to-be-changed.pdf", "new-file-name.pdf");