code: private static void loadDriver(String classname) throws ClassNotFoundException, InstantiationException, IllegalAccessException {
  		if(!driversLoaded.containsKey(classname)) {
  			Object O = Class.forName(classname).newInstance();
  			driversLoaded.putIfAbsent(classname, O);
  		}
  	}
docs: Loads a driver at most once.