转换为十六进制字节，字节十六进制。

Convert hex to byte and byte to hex.

public static byte[] hexStringToByteArray(String s) {
                int len = s.length();
                byte[] data = new byte[len/2];

                for(int i = 0; i < len; i+=2){
                    data[i/2] = (byte) ((Character.digit(s.charAt(i), 16) << 4) + Character.digit(s.charAt(i+1), 16));
                }

                return data;
            }

final protected static char[] hexArray = {'0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F'};
public static String byteArrayToHexString(byte[] bytes) {
            char[] hexChars = new char[bytes.length*2];
            int v;

            for(int j=0; j < bytes.length; j++) {
                v = bytes[j] & 0xFF;
                hexChars[j*2] = hexArray[v>>>4];
                hexChars[j*2 + 1] = hexArray[v & 0x0F];
            }

            return new String(hexChars);
        }