Base64Utils.java

package com.firefly.utils.codec;

import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;

public abstract class Base64Utils {

	private static final Charset DEFAULT_CHARSET = StandardCharsets.UTF_8;
	private static final Base64Delegate delegate = new CommonsCodecBase64Delegate();

	/**
	 * Base64-encode the given byte array.
	 * 
	 * @param src
	 *            the original byte array (may be {@code null})
	 * @return the encoded byte array (or {@code null} if the input was
	 *         {@code null})
	 *
	 */
	public static byte[] encode(byte[] src) {
		return delegate.encode(src);
	}

	/**
	 * Base64-decode the given byte array.
	 * 
	 * @param src
	 *            the encoded byte array (may be {@code null})
	 * @return the original byte array (or {@code null} if the input was
	 *         {@code null})
	 * 
	 */
	public static byte[] decode(byte[] src) {
		return delegate.decode(src);
	}

	/**
	 * Base64-encode the given byte array using the RFC 4868
	 * "URL and Filename Safe Alphabet".
	 * 
	 * @param src
	 *            the original byte array (may be {@code null})
	 * @return the encoded byte array (or {@code null} if the input was
	 *         {@code null})
	 * 
	 */
	public static byte[] encodeUrlSafe(byte[] src) {
		return delegate.encodeUrlSafe(src);
	}

	/**
	 * Base64-decode the given byte array using the RFC 4868
	 * "URL and Filename Safe Alphabet".
	 * 
	 * @param src
	 *            the encoded byte array (may be {@code null})
	 * @return the original byte array (or {@code null} if the input was
	 *         {@code null})
	 * 
	 */
	public static byte[] decodeUrlSafe(byte[] src) {
		return delegate.decodeUrlSafe(src);
	}

	/**
	 * Base64-encode the given byte array to a String.
	 * 
	 * @param src
	 *            the original byte array (may be {@code null})
	 * @return the encoded byte array as a UTF-8 String (or {@code null} if the
	 *         input was {@code null})
	 */
	public static String encodeToString(byte[] src) {
		if (src == null) {
			return null;
		}
		if (src.length == 0) {
			return "";
		}

		return new String(delegate.encode(src), DEFAULT_CHARSET);
	}

	/**
	 * Base64-decode the given byte array from an UTF-8 String.
	 * 
	 * @param src
	 *            the encoded UTF-8 String (may be {@code null})
	 * @return the original byte array (or {@code null} if the input was
	 *         {@code null})
	 */
	public static byte[] decodeFromString(String src) {
		if (src == null) {
			return null;
		}
		if (src.length() == 0) {
			return new byte[0];
		}

		return delegate.decode(src.getBytes(DEFAULT_CHARSET));
	}

	/**
	 * Base64-encode the given byte array to a String using the RFC 4868
	 * "URL and Filename Safe Alphabet".
	 * 
	 * @param src
	 *            the original byte array (may be {@code null})
	 * @return the encoded byte array as a UTF-8 String (or {@code null} if the
	 *         input was {@code null})
	 * 
	 */
	public static String encodeToUrlSafeString(byte[] src) {
		return new String(delegate.encodeUrlSafe(src), DEFAULT_CHARSET);
	}

	/**
	 * Base64-decode the given byte array from an UTF-8 String using the RFC
	 * 4868 "URL and Filename Safe Alphabet".
	 * 
	 * @param src
	 *            the encoded UTF-8 String (may be {@code null})
	 * @return the original byte array (or {@code null} if the input was
	 *         {@code null})
	 * 
	 */
	public static byte[] decodeFromUrlSafeString(String src) {
		return delegate.decodeUrlSafe(src.getBytes(DEFAULT_CHARSET));
	}

	interface Base64Delegate {

		byte[] encode(byte[] src);

		byte[] decode(byte[] src);

		byte[] encodeUrlSafe(byte[] src);

		byte[] decodeUrlSafe(byte[] src);
	}

	static class CommonsCodecBase64Delegate implements Base64Delegate {

		private final Base64 base64 = new Base64();

		private final Base64 base64UrlSafe = new Base64(0, null, true);

		@Override
		public byte[] encode(byte[] src) {
			return this.base64.encode(src);
		}

		@Override
		public byte[] decode(byte[] src) {
			return this.base64.decode(src);
		}

		@Override
		public byte[] encodeUrlSafe(byte[] src) {
			return this.base64UrlSafe.encode(src);
		}

		@Override
		public byte[] decodeUrlSafe(byte[] src) {
			return this.base64UrlSafe.decode(src);
		}

	}
}