十六进制的字符串和字节数组之间的转换

**
* This class provides convenient functions to convert hex string to byte array and vice versa.*
*/
public class HexUtil {

private static final String HEX_CHARS = "0123456789abcdef";

private HexUtil() {}

/**
* Converts a byte array to hex string.
*
* @param b -
*            the input byte array
* @return hex string representation of b.
*/

public static String toHexString(byte[] b) {
StringBuffer sb = new StringBuffer();
for (int i = 0; i < b.length; i++) {
sb.append(HexUtil.HEX_CHARS.charAt(b[i] >>> 4 & 0x0F));
sb.append(HexUtil.HEX_CHARS.charAt(b[i] & 0x0F));
}
return sb.toString();
}

/**
* Converts a hex string into a byte array.
* @param s -
*            string to be converted
* @return byte array converted from s
*/
public static byte[] toByteArray(String s) {
byte[] buf = new byte[s.length() / 2];
int j = 0;
for (int i = 0; i < buf.length; i++) {
buf[i] = (byte) ((Character.digit(s.charAt(j++), 16) << 4) | Character.digit(s.charAt(j++), 16));
}
return buf;
}

}