base64converter.java

Base64 Encoder in JAVA

/* Cortado - a video player java applet
 * Copyright (C) 2004 Fluendo S.L.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Street #330, Boston, MA 02111-1307, USA.
 */

public class Base64Converter
{
  public static final char[] alphabet = {
    'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H',	//  0 to  7
    'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',	//  8 to 15
    'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X',	// 16 to 23
    'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',	// 24 to 31
    'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n',	// 32 to 39
    'o', 'p', 'q', 'r', 's', 't', 'u', 'v',	// 40 to 47
    'w', 'x', 'y', 'z', '0', '1', '2', '3',	// 48 to 55
    '4', '5', '6', '7', '8', '9', '+', '/'
  };				// 56 to 63


  public static String encode (byte[]octetString)
  {
    int bits24;
    int bits6;

    char[] out = new char[((octetString.length - 1) / 3 + 1) * 4];

    int outIndex = 0;
    int i = 0;

    while ((i + 3) <= octetString.length)
      {
	// store the octets
	bits24 = (octetString[i++] & 0xFF) << 16;
	bits24 |= (octetString[i++] & 0xFF) << 8;
	bits24 |= (octetString[i++] & 0xFF) << 0;

	bits6 = (bits24 & 0x00FC0000) >> 18;
	out[outIndex++] = alphabet[bits6];
	bits6 = (bits24 & 0x0003F000) >> 12;
	out[outIndex++] = alphabet[bits6];
	bits6 = (bits24 & 0x00000FC0) >> 6;
	out[outIndex++] = alphabet[bits6];
	bits6 = (bits24 & 0x0000003F);
	out[outIndex++] = alphabet[bits6];
      }

    if (octetString.length - i == 2)
      {
	bits24 = (octetString[i] & 0xFF) << 16;
	bits24 |= (octetString[i + 1] & 0xFF) << 8;

	bits6 = (bits24 & 0x00FC0000) >> 18;
	out[outIndex++] = alphabet[bits6];
	bits6 = (bits24 & 0x0003F000) >> 12;
	out[outIndex++] = alphabet[bits6];
	bits6 = (bits24 & 0x00000FC0) >> 6;
	out[outIndex++] = alphabet[bits6];

	out[outIndex++] = '=';
      }
    else if (octetString.length - i == 1)
      {
	bits24 = (octetString[i] & 0xFF) << 16;

	bits6 = (bits24 & 0x00FC0000) >> 18;
	out[outIndex++] = alphabet[bits6];
	bits6 = (bits24 & 0x0003F000) >> 12;
	out[outIndex++] = alphabet[bits6];

	out[outIndex++] = '=';
	out[outIndex++] = '=';
      }
    return new String (out);
  }
}