code: public static boolean checkModified(String address, String lastDigest) {
          // 检查文件是否被修改了
          String newDigest = calMD5Checksum(address);
          return !StringUtils.equals(newDigest, lastDigest);
      }
docs: Check file's digest.
  
  @param address    the address
  @param lastDigest the update digest
  @return true被修改，false未被修改