LoggerFactory.getLogger“root”与“class”名称的区别是什么？

Question

I'm trying to find the answer about the differences between:

class MyClass {
    private static Logger logger = LoggerFactory.getLogger(Logger.ROOT_LOGGER_NAME);
}

and:

class MyClass {
    private static Logger logger = LoggerFactory.getLogger(MyClass.class);
}

Is it only useful with you are planning to do a fine logging setup? Like separate the log of the class in a different file, print more/less informations for each one, etc.

I have this doubt because most of my classes I use LoggerFactory.getLogger(MyClass.class) but I think the LoggerFactory.getLogger(Logger.ROOT_LOGGER_NAME) is enough in the most of the cases.

Thanks!

Answer 1

Is it only useful with you are planning to do a fine logging setup? Like separate the log of the class in a different file, print more/less informations for each one, etc.

This is correct. By controlling your logging down to the class level, by giving each class their own logger, you can more finely control the logging. For example, we typically log all log entries (regardless of level) for classes in our packages, eg my.employer.com.team.project . We then log ERROR for all other loggers. We then have the ability to view all the loggers that are being used on the application and can remotely enable/disable any logger we want in real-time.

I have this doubt because most of my classes I use LoggerFactory.getLogger(MyClass.class) but I think the LoggerFactory.getLogger(Logger.ROOT_LOGGER_NAME) is enough in the most of the cases.

If you give all your classes the same logger, then they will all behave in the same way. I think you are right that for most cases you will treat all your classes' logging the same way, but that is not always the case. Also, if you are writing library code, then you must not use the root logger because now you remove the ability of the user's of your library to tune your libraries' logs.