将byte数组转化为16进制字符串

private static String byte2Hex(byte[] b) {
    if (b == null) {
        return null;
    }

    StringBuffer result = new StringBuffer();

    for (int i = 0; i < b.length; i++) {
        result.append(Integer.toString((b[i] & 0xff) + 0x100, 16).substring(1));
    }

    return result.toString();
}