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Base64Coder.java

package fix;

/**
 * A Base64 Encoder/Decoder.
 * 
 * $Date: 2010-02-04 12:01:01 +0100 (Thu, 04 Feb 2010) $
 * $Revision: 30 $
 * $Author: roth $
 * 
 * This class is used to encode and decode data in Base64 format as described in
 * RFC 1521.
 * 
 * This is "Open Source" software and released under the GNU/LGPL
 * (http://www.gnu.org/licenses/lgpl.html) license.
 * It is provided "as is" without warranty of any kind.
 * Copyright 2003: Christian d'Heureuse, Inventec Informatik AG, Switzerland.
 * Home page: http://www.source-code.biz
 * 
 * Version history:
 * 2003-07-22 Christian d'Heureuse (chdh): Module created.
 * 2005-08-11 chdh: Lincense changed from GPL to LGPL.
 * 2006-11-21 chdh:
 * & Method encode(String) renamed to encodeString(String).
 * & Method decode(String) renamed to decodeString(String).
 * & New method encode(byte[],int) added.
 * & New method decode(String) added.
 */

00029 public class Base64Coder {

      // Mapping table from 6-bit nibbles to Base64 characters.
      private static char[] map1 = new char[64];
      static {
            int i = 0;
            for (char c = 'A'; c <= 'Z'; c++)
                  map1[i++] = c;
            for (char c = 'a'; c <= 'z'; c++)
                  map1[i++] = c;
            for (char c = '0'; c <= '9'; c++)
                  map1[i++] = c;
            map1[i++] = '+';
            map1[i++] = '/';
      }

      // Mapping table from Base64 characters to 6-bit nibbles.
      private static byte[] map2 = new byte[128];
      static {
            for (int i = 0; i < map2.length; i++)
                  map2[i] = -1;
            for (int i = 0; i < 64; i++)
                  map2[map1[i]] = (byte) i;
      }

      /**
       * Encodes a string into Base64 format. No blanks or line breaks are
       * inserted.
       * 
       * @param s
       *            a String to be encoded.
       * @return A String with the Base64 encoded data.
       */
00062       public static String encodeString(String s) {
            return new String(encode(s.getBytes()));
      }

      /**
       * Encodes a byte array into Base64 format. No blanks or line breaks are
       * inserted.
       * 
       * @param in
       *            an array containing the data bytes to be encoded.
       * @return A character array with the Base64 encoded data.
       */
00074       public static char[] encode(byte[] in) {
            return encode(in, in.length);
      }

      /**
       * Encodes a byte array into Base64 format. No blanks or line breaks are
       * inserted.
       * 
       * @param in
       *            an array containing the data bytes to be encoded.
       * @param iLen
       *            number of bytes to process in <code>in</code>.
       * @return A character array with the Base64 encoded data.
       */
00088       public static char[] encode(byte[] in, int iLen) {
            int oDataLen = (iLen * 4 + 2) / 3; // output length without padding
            int oLen = ((iLen + 2) / 3) * 4; // output length including padding
            char[] out = new char[oLen];
            int ip = 0;
            int op = 0;
            while (ip < iLen) {
                  int i0 = in[ip++] & 0xff;
                  int i1 = ip < iLen ? in[ip++] & 0xff : 0;
                  int i2 = ip < iLen ? in[ip++] & 0xff : 0;
                  int o0 = i0 >>> 2;
                  int o1 = ((i0 & 3) << 4) | (i1 >>> 4);
                  int o2 = ((i1 & 0xf) << 2) | (i2 >>> 6);
                  int o3 = i2 & 0x3F;
                  out[op++] = map1[o0];
                  out[op++] = map1[o1];
                  out[op] = op < oDataLen ? map1[o2] : '=';
                  op++;
                  out[op] = op < oDataLen ? map1[o3] : '=';
                  op++;
            }
            return out;
      }

      /**
       * Decodes a string from Base64 format.
       * 
       * @param s
       *            a Base64 String to be decoded.
       * @return A String containing the decoded data.
       * @throws IllegalArgumentException
       *             if the input is not valid Base64 encoded data.
       */
00121       public static String decodeString(String s) {
            return new String(decode(s));
      }

      /**
       * Decodes a byte array from Base64 format.
       * 
       * @param s
       *            a Base64 String to be decoded.
       * @return An array containing the decoded data bytes.
       * @throws IllegalArgumentException
       *             if the input is not valid Base64 encoded data.
       */
00134       public static byte[] decode(String s) {
            return decode(s.toCharArray());
      }

      /**
       * Decodes a byte array from Base64 format. No blanks or line breaks are
       * allowed within the Base64 encoded data.
       * 
       * @param in
       *            a character array containing the Base64 encoded data.
       * @return An array containing the decoded data bytes.
       * @throws IllegalArgumentException
       *             if the input is not valid Base64 encoded data.
       */
00148       public static byte[] decode(char[] in) {
            int iLen = in.length;
            if (iLen % 4 != 0)
                  throw new IllegalArgumentException(
                              "Length of Base64 encoded input string is not a multiple of 4.");
            while (iLen > 0 && in[iLen - 1] == '=')
                  iLen--;
            int oLen = (iLen * 3) / 4;
            byte[] out = new byte[oLen];
            int ip = 0;
            int op = 0;
            while (ip < iLen) {
                  int i0 = in[ip++];
                  int i1 = in[ip++];
                  int i2 = ip < iLen ? in[ip++] : 'A';
                  int i3 = ip < iLen ? in[ip++] : 'A';
                  if (i0 > 127 || i1 > 127 || i2 > 127 || i3 > 127)
                        throw new IllegalArgumentException(
                                    "Illegal character in Base64 encoded data.");
                  int b0 = map2[i0];
                  int b1 = map2[i1];
                  int b2 = map2[i2];
                  int b3 = map2[i3];
                  if (b0 < 0 || b1 < 0 || b2 < 0 || b3 < 0)
                        throw new IllegalArgumentException(
                                    "Illegal character in Base64 encoded data.");
                  int o0 = (b0 << 2) | (b1 >>> 4);
                  int o1 = ((b1 & 0xf) << 4) | (b2 >>> 2);
                  int o2 = ((b2 & 3) << 6) | b3;
                  out[op++] = (byte) o0;
                  if (op < oLen)
                        out[op++] = (byte) o1;
                  if (op < oLen)
                        out[op++] = (byte) o2;
            }
            return out;
      }

      // Dummy constructor.
      private Base64Coder() {
      }

}

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