code: private static String messageDigest(String key, String string, int scale) throws NoSuchAlgorithmException {
          MessageDigest md = MessageDigest.getInstance(key);
          md.update(string.getBytes());
          BigInteger bigInteger = new BigInteger(md.digest());
          return bigInteger.toString(scale);
      }
docs: 消息摘要算法，单向加密
  
  @param key {@link String}
  @param string {@link String}
  @param scale {@link Integer}
  
  @return {@link String}
  
  @throws NoSuchAlgorithmException 异常