code: protected static String sha1(String... strings) {
          try {
              Arrays.sort(strings);
              MessageDigest md = MessageDigest.getInstance("SHA-1");
              for (String s : strings) md.update(s.getBytes());
              return Utility.binToHexString(md.digest());
          } catch (Exception e) {
              throw new RuntimeException("SHA encryption to generate signature failure", e);
          }
      }
docs: 用SHA1算法生成安全签名
  <p>
  @param strings String[]
  
  @return 安全签名