code: public static Prop use(File file, String encoding) {
  		Prop result = map.get(file.getName());
  		if (result == null) {
  			synchronized (PropKit.class) {
  				result = map.get(file.getName());
  				if (result == null) {
  					result = new Prop(file, encoding);
  					map.put(file.getName(), result);
  					if (PropKit.prop == null) {
  						PropKit.prop = result;
  					}
  				}
  			}
  		}
  		return result;
  	}
docs: Use the properties file bye File object. It will loading the properties file if not loading.
  <p>
  Example:<br>
  PropKit.use(new File("/var/config/my_config.txt"), "UTF-8");<br>
  Strig userName = PropKit.use("my_config.txt").get("userName");
  
  @param file the properties File object
  @param encoding the encoding