Java Utilities Module

Contains helper classes that I find useful every now and then.

Classes Summary

ImageCompressionUtils

Used to compress image files to JPEG format using the desired quality for the compressed image.

Sample Usage

// Compression quality (value >= 0 and <= 1)
final float quality = 0.35f;

// Compressing to bytes from source image bytes
byte[] compressed = ImageCompressionUtils.compressImage(sourceBytes, quality);

ImageCompressor

A Thread-Safe Object-Oriented wrapper for the ImageCompressionUtils utility class with Base64 and method chaining support.

Sample Usage

// Creating a new instance and setting the compressed image quality
ImageCompressor mImageCompressor = new ImageCompressor().setCompressedImageQuality(0.75f);

// Compressing an image to byte array
byte[] compressed = mImageCompressor.setSourceImage(sourceBytes).compressImageToByteArray();

// Modifying the compressed image quality, and compressing a new image to Base64
String compressedBase64 = mImageCompressor.setCompressedImageQuality(0.35f)
					  .setSourceImage(sourceBytesTwo)
  					  .compressImageToBase64();

ConcurrentCache

Cache implementation with a periodic memory clean up process for objects that haven't been accessed for a specified period of time. Implements AutoCloseable to shut down the cleanup executor.

Sample Usage

long cleanUpInterval = 100; // milliseconds
long objectTTL = 2000; // milliseconds
int cacheSize = 25;

try(ConcurrentCache<Integer, String> mCache = new ConcurrentCache<>(objectTTL, cleanUpInterval, cacheSize)){
    mCache.put(1, "value");
    String value = mCache.get(1);
}

PBKDF2Helper

Wrapper class to help manipulate PBKDF2 parameters and generate keys.

Sample Usage

// Using the builder
PBKDF2Helper mHelper = new PBKDF2Helper.Builder(KeySize.KEY_256)
                .iterations(Iterations.MEDIUM)
                .saltSize(SaltSize.SALT_128)
                .build();

// Generating a key (password as char[] for secure memory handling)
char[] password = "myPassword".toCharArray();
byte[] key = mHelper.createKeyFromPassword(password);

// Getting configurations for storage
String config = mHelper.getPbkdf2Configurations();

// Creation using the configurations string
PBKDF2Helper mHelper = new PBKDF2Helper.Builder(config).build();

FileEncryptorAES

Used to encrypt files using AES-GCM with PBKDF2. Instances are single-use.

Sample Usage

// Using factory method for creation (password as char[])
char[] password = "myPassword".toCharArray();
FileEncryptorAES mEncryptor = FileEncryptorAES.createEncryptorWithHighSecurityParams(password);

// Setting the progress monitor
mEncryptor.setProgressMonitor((int progress) -> System.out.println(progress));

// Encryption
BufferedInputStream mInputStream = new BufferedInputStream(new FileInputStream(mSourceFile));
BufferedOutputStream mOutputStream = new BufferedOutputStream(new FileOutputStream(mTargetFile));
mEncryptor.encrypt(mInputStream, mOutputStream);

FileDecryptorAES

Used to decrypt files encrypted with FileEncryptorAES. Implements AutoCloseable to zero the internal password copy.

Sample Usage

// Creation (password as char[])
char[] password = "myPassword".toCharArray();
try(FileDecryptorAES mDecryptor = new FileDecryptorAES(password)){

    // Setting the progress monitor
    mDecryptor.setProgressMonitor((int progress) -> System.out.println(progress));

    // Decryption
    BufferedInputStream mInputStream = new BufferedInputStream(new FileInputStream(mSourceFile));
    BufferedOutputStream mOutputStream = new BufferedOutputStream(new FileOutputStream(mTargetFile));
    mDecryptor.decrypt(mInputStream, mOutputStream);
}

Secure Preferences

Provides an AES encryption layer over the java.util.prefs.Preferences class. Implements AutoCloseable to zero the internal password copy.

Sample Usage

// Setting up the prefs (password as char[])
try(SecurePreferences mPreferences = new SecurePreferencesImpl("test-node", "pa$$word".toCharArray())){

    // Storing a string value
    String str = "test-data";
    mPreferences.putString("string", str);

    // Getting the value
    Optional<String> mOptional = mPreferences.getString("string");
    if(mOptional.isPresent()){
        String loaded = mOptional.get();
    }
}

CloneUtils

Used to deep clone objects that implements the Serializable interface. (Any objects used by the class must also implement Serializable).

Sample Usage

SomeObject clone = CloneUtils.deepClone(origin, SomeObject.class);

LuhnChecker

Used to check card numbers using the Luhn formula.

Sample Usage

boolean isValid = LuhnChecker.checkNumberValidity("4532136548631895");

Developed By

• Hussain Al-Derry

  Email - hussain.derry@gmail.com

License

Copyright 2017 Hussain Al-Derry

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

   http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.