Retrieving Loggers

Calling the LoggerFactory.getLogger method with the same name will always return a reference to the exact same logger object.

For example, in

Logger x = LoggerFactory.getLogger("wombat"); 
Logger y = LoggerFactory.getLogger("wombat");

x and y refer to exactly the same logger object.

Thus, it is possible to configure a logger and then to retrieve the same instance somewhere else in the code without passing around references. In fundamental contradiction to biological parenthood, where parents always precede their children, logback loggers can be created and configured in any order. In particular, a "parent" logger will find and link to its descendants even if it is instantiated after them.

Configuration of the logback environment is typically done at application initialization. The preferred way is by reading a configuration file. This approach will be discussed shortly.

Logback makes it easy to name loggers by software component. This can be accomplished by instantiating a logger in each class, with the logger name equal to the fully qualified name of the class. This is a useful and straightforward method of defining loggers. As the log output bears the name of the generating logger, this naming strategy makes it easy to identify the origin of a log message. However, this is only one possible, albeit common, strategy for naming loggers. Logback does not restrict the possible set of loggers. As a developer, you are free to name loggers as you wish.

Nevertheless, naming loggers after the class where they are located seems to be the best general strategy known so far.