/** * Converts a hexadecimal character to an integer. * * @param ch * A character to convert to an integer digit * @param index * The index of the character in the source * @return An integer * @throws DecoderException * Thrown if ch is an illegal hex character */ protected static int toDigit(char ch, int index) throws DecoderException { int digit = Character.digit(ch, 16); if (digit == -1) { throw new DecoderException("Illegal hexadecimal character " + ch + " at index " + index); } return digit; }
/** * Converts a String or an array of character bytes representing hexadecimal values into an array of bytes of those * same values. The returned array will be half the length of the passed String or array, as it takes two characters * to represent any given byte. An exception is thrown if the passed char array has an odd number of elements. * * @param object * A String or, an array of character bytes containing hexadecimal digits * @return A byte array containing binary data decoded from the supplied byte array (representing characters). * @throws DecoderException * Thrown if an odd number of characters is supplied to this function or the object is not a String or * char[] * @see #decodeHex(char[]) */ public Object decode(Object object) throws DecoderException { try { char[] charArray = object instanceof String ? ((String) object).toCharArray() : (char[]) object; return decodeHex(charArray); } catch (ClassCastException e) { throw new DecoderException(e.getMessage(), e); } }
/** * Converts an array of character bytes representing hexadecimal values into an array of bytes of those same values. * The returned array will be half the length of the passed array, as it takes two characters to represent any given * byte. An exception is thrown if the passed char array has an odd number of elements. * * @param array * An array of character bytes containing hexadecimal digits * @return A byte array containing binary data decoded from the supplied byte array (representing characters). * @throws DecoderException * Thrown if an odd number of characters is supplied to this function * @see #decodeHex(char[]) */ public byte[] decode(byte[] array) throws DecoderException { try { return decodeHex(new String(array, getCharsetName()).toCharArray()); } catch (UnsupportedEncodingException e) { throw new DecoderException(e.getMessage(), e); } }
/** * Converts an array of characters representing hexadecimal values into an array of bytes of those same values. The * returned array will be half the length of the passed array, as it takes two characters to represent any given * byte. An exception is thrown if the passed char array has an odd number of elements. * * @param data * An array of characters containing hexadecimal digits * @return A byte array containing binary data decoded from the supplied char array. * @throws DecoderException * Thrown if an odd number or illegal of characters is supplied */ public static byte[] decodeHex(char[] data) throws DecoderException { int len = data.length; if ((len & 0x01) != 0) { throw new DecoderException("Odd number of characters."); } byte[] out = new byte[len >> 1]; // two characters form the hex value. for (int i = 0, j = 0; j < len; i++) { int f = toDigit(data[j], j) << 4; j++; f = f | toDigit(data[j], j); j++; out[i] = (byte) (f & 0xFF); } return out; }