public List<Map<String, Object>> findKColumnsCNVD(int offset, int num, List<Object> params)
      throws SQLException {
    String sql =
        "SELECT * FROM cnvd_net_device LIMIT "
            + String.valueOf(num)
            + " OFFSET "
            + String.valueOf(offset);
    List<Map<String, Object>> list = jdbcUtils.findSimplesResult(sql, params);
    Map<String, Object> map = new HashMap<String, Object>();
    Date date;
    DateFormat dataFormat = new SimpleDateFormat("yyyy-MM-dd");
    for (int i = 0; i < list.size(); i++) {
      map = list.get(i);

      /*
       * The timestamps of python and Java are different.
       * Java uses millisecond while python uses seconds.
       */

      String uploadTime = dataFormat.format((int) map.get("modify_time") * 1000.0);
      String publishTime = dataFormat.format((int) map.get("publish_time") * 1000.0);
      String modifyTime = dataFormat.format((int) map.get("modify_time") * 1000.0);
      list.get(i).put("publish_time", publishTime);
      list.get(i).put("upload_time", uploadTime);
      list.get(i).put("modify_time", modifyTime);
    }
    return list;
  }
 public List<String> findBrands() throws SQLException {
   String sql = "SELECT distinct threat_rank  FROM vulnerability_info.cnvd_net_device";
   List<Map<String, Object>> list = jdbcUtils.findSimplesResult(sql, null);
   List<String> ret = new ArrayList<String>();
   for (int i = 0; i < list.size(); i++) {
     ret.add((String) list.get(i).get("threat_rank"));
   }
   return ret;
 }