cn.bestwu.lang.util.Hex Maven / Gradle / Ivy
package cn.bestwu.lang.util;
/**
* @author Peter Wu
*/
public final class Hex {
private static final char[] HEX = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
'a', 'b', 'c', 'd', 'e', 'f'};
public static char[] encode(byte[] bytes) {
final int nBytes = bytes.length;
char[] result = new char[2 * nBytes];
int j = 0;
for (byte aByte : bytes) {
// Char for top 4 bits
result[j++] = HEX[(0xF0 & aByte) >>> 4];
// Bottom 4
result[j++] = HEX[(0x0F & aByte)];
}
return result;
}
public static byte[] decode(CharSequence s) {
int nChars = s.length();
if (nChars % 2 != 0) {
throw new IllegalArgumentException(
"Hex-encoded string must have an even number of characters");
}
byte[] result = new byte[nChars / 2];
for (int i = 0; i < nChars; i += 2) {
int msb = Character.digit(s.charAt(i), 16);
int lsb = Character.digit(s.charAt(i + 1), 16);
if (msb < 0 || lsb < 0) {
throw new IllegalArgumentException("Non-hex character in input: " + s);
}
result[i / 2] = (byte) ((msb << 4) | lsb);
}
return result;
}
}