code: public void connectDatabase()
      {
          try 
          {
              _con = DriverManager.getConnection(_url, _userName, _password);
          }
          catch(SQLException e)
          {
              log.warn("UserRealm " + getName()
                        + " could not connect to database; will try later", e);
          }
      }
docs: (re)Connect to database with parameters setup by loadConfig()