org.jboss.resteasy.util.Hex Maven / Gradle / Ivy
package org.jboss.resteasy.util;
public class Hex
{
/**
* Used building output as Hex
*/
private static final char[] DIGITS = {
'0', '1', '2', '3', '4', '5', '6', '7',
'8', '9', 'a', 'b', 'c', 'd', 'e', 'f'
};
/**
* Converts an array of characters representing hexidecimal 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 hexidecimal 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(String str)
{
char[] data = str.toCharArray();
int len = data.length;
if ((len & 0x01) != 0)
{
throw new RuntimeException("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;
}
/**
* 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
*/
protected static int toDigit(char ch, int index)
{
int digit = Character.digit(ch, 16);
if (digit == -1)
{
throw new RuntimeException("Illegal hexadecimal character " + ch + " at index " + index);
}
return digit;
}
/**
* Converts an array of bytes into an array of characters representing the hexidecimal values of each byte in order.
* The returned array will be double the length of the passed array, as it takes two characters to represent any
* given byte.
*
* @param data a byte[] to convert to Hex characters
* @return A char[] containing hexidecimal characters
*/
public static String encodeHex(byte[] data)
{
int l = data.length;
char[] out = new char[l << 1];
// two characters form the hex value.
for (int i = 0, j = 0; i < l; i++)
{
out[j++] = DIGITS[(0xF0 & data[i]) >>> 4];
out[j++] = DIGITS[0x0F & data[i]];
}
return new String(out);
}
}