public static String toHexString(final byte[] bytes) {
        final StringBuffer sb = new StringBuffer();
        for (final byte b : bytes) {
            byte2hex(b, sb);
        }
        return sb.toString();

    }
All possible chars for representing a number as a String
metamorphosis-commons/src/main/java/com/taobao/metamorphosis/network/ByteUtils.java