code: public static String byteArrayToHexString(byte[] b) {
         StringBuilder resultSb = new StringBuilder();
         for (byte aB : b) {
             resultSb.append(byteToHexString(aB));
         }
         return resultSb.toString();
     }
docs: 转换字节数组为16进制字串
  @param b 字节数组
  @return 16进制字串