Question

I know its a package difference

1) org.apache.log4j.Logger logger = Logger.getLogger(clazz);

2) org.apache.commons.logging.Log log = LogFactory.getLog(clazz);

The first one uses loggers via log4j and the second one uses commons.logging. We have a huge project where in some classes loggers are configured using log4j and in some cases its commons.logging.

I did find a log4j property file though.Is there a similar property file for commons.logging ? Where do I configure for commons-logging ?. I am unable to see the logs generated by commons-logging.

Any help is appreciated.

Answer 1

Yes, commons-logging is a facade API that was suppose to abstract you from underlying logging framework (in practice there was a choice between log4j and java.util.logging) so that you could switch from one to another without touching the code – just by switching libraries available on the CLASSPATH.

Unfortunately due to some design mistakes it had issues with complex class-loading environments, like application servers. Currently it is effectively superseded by slf4j.

In your case I would recommend sticking with one API – either Log4J or commons-logging, even though commons-logging will (most likely) delegate to log4J. You can also migrate to using SLF4J and install bridging APIs, but this is slightly more advanced.