Base64.java

package com.ikokoon.toolkit;

/*
 * Base64.java
 *
 * Brazil project web application toolkit,
 * export version: 2.0
 * Copyright (c) 2000-2002 Sun Microsystems, Inc.
 *
 * Sun Public License Notice
 *
 * The contents of this file are subject to the Sun Public License
 * Version 1.0 (the "License"). You may not use this file except in
 * compliance with the License. A copy of the License is included as
 * the file "license.terms", and also available at
 * http://www.sun.com/
 *
 * The Original Code is from:
 *    Brazil project web application toolkit release 2.0.
 * The Initial Developer of the Original Code is: cstevens.
 * Portions created by cstevens are Copyright (C) Sun Microsystems,
 * Inc. All Rights Reserved.
 *
 * Contributor(s): cstevens, suhler.
 *
 * Version:  1.9
 * Created by cstevens on 00/04/17
 * Last modified by suhler on 02/07/24 10:49:48
 */

/**
 * Utility to base64 encode and decode a string.
 *
 * @author Stephen Uhler
 * @version 1.9, 02/07/24
 */
public class Base64 {
	static byte[] encodeData;
	static String charSet = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

	static {
		encodeData = new byte[64];
		for (int i = 0; i < 64; i++) {
			byte c = (byte) charSet.charAt(i);
			encodeData[i] = c;
		}
	}

	private Base64() {
	}

	/**
	 * base-64 encode a string
	 *
	 * @param s
	 *            The ascii string to encode
	 * @return The base64 encoded result
	 */
	public static String encode(String s) {
		return encode(s.getBytes());
	}

	/**
	 * base-64 encode a byte array
	 *
	 * @param src
	 *            The byte array to encode
	 * @return The base64 encoded result
	 */
	public static String encode(byte[] src) {
		return encode(src, 0, src.length);
	}

	/**
	 * base-64 encode a byte array
	 *
	 * @param src
	 *            The byte array to encode
	 * @param start
	 *            The starting index
	 * @param length
	 *            The number of bytes
	 * @return The base64 encoded result
	 */
	public static String encode(byte[] src, int start, int length) {
		byte[] dst = new byte[(length + 2) / 3 * 4 + length / 72];
		int x = 0;
		int dstIndex = 0;
		int state = 0; // which char in pattern
		int old = 0; // previous byte
		int len = 0; // length decoded so far
		int max = length + start;
		for (int srcIndex = start; srcIndex < max; srcIndex++) {
			x = src[srcIndex];
			switch (++state) {
			case 1:
				dst[dstIndex++] = encodeData[(x >> 2) & 0x3f];
				break;
			case 2:
				dst[dstIndex++] = encodeData[((old << 4) & 0x30) | ((x >> 4) & 0xf)];
				break;
			case 3:
				dst[dstIndex++] = encodeData[((old << 2) & 0x3C) | ((x >> 6) & 0x3)];
				dst[dstIndex++] = encodeData[x & 0x3F];
				state = 0;
				break;
			}
			old = x;
			if (++len >= 72) {
				dst[dstIndex++] = (byte) '\n';
				len = 0;
			}
		}

		/*
		 * now clean up the end bytes
		 */

		switch (state) {
		case 1:
			dst[dstIndex++] = encodeData[(old << 4) & 0x30];
			dst[dstIndex++] = (byte) '=';
			dst[dstIndex++] = (byte) '=';
			break;
		case 2:
			dst[dstIndex++] = encodeData[(old << 2) & 0x3c];
			dst[dstIndex++] = (byte) '=';
			break;
		}
		return new String(dst);
	}

	/**
	 * A Base64 decoder. This implementation is slow, and doesn't handle wrapped lines. The output is undefined if there are errors in the input.
	 *
	 * @param s
	 *            a Base64 encoded string
	 * @return The byte array with the decoded result
	 */
	public static byte[] decode(String s) {
		int end = 0; // end state
		if (s.endsWith("=")) {
			end++;
		}
		if (s.endsWith("==")) {
			end++;
		}
		int len = (s.length() + 3) / 4 * 3 - end;
		byte[] result = new byte[len];
		int dst = 0;
		try {
			for (int src = 0; src < s.length(); src++) {
				int code = charSet.indexOf(s.charAt(src));
				if (code == -1) {
					break;
				}
				switch (src % 4) {
				case 0:
					result[dst] = (byte) (code << 2);
					break;
				case 1:
					result[dst++] |= (byte) ((code >> 4) & 0x3);
					result[dst] = (byte) (code << 4);
					break;
				case 2:
					result[dst++] |= (byte) ((code >> 2) & 0xf);
					result[dst] = (byte) (code << 6);
					break;
				case 3:
					result[dst++] |= (byte) (code & 0x3f);
					break;
				}
			}
		} catch (ArrayIndexOutOfBoundsException e) {
		}
		return result;
	}

	/**
	 * Test the decoder and encoder. Call as <code>Base64 [string]</code>.
	 */
	public static void main(String[] args) {
		System.out.println("encode: " + args[0] + " -> (" + encode(args[0]) + ")");
		System.out.println("decode: " + args[0] + " -> (" + new String(decode(args[0])) + ")");
	}
}