315 After adding log4j to my application I get the following output every time I execute my application: log4j:WARN No appenders could be found for logger (slideselector.facedata.FaceDataParser). log4j:WARN Please initialize the log4j system properly. It seems this means a configuration file is missing.
That only works for log4j 1.x . For log4j 2.x, the config syntax is different, you need to define a custom logger logger.example.name=com.example logger.example.level=DEBUG
RBB, you have to use log4j-slf4j-impl assuming you are still on SLF4J 1, yes. So which other dependencies (apart from log4j-slf4j-impl) should I add to my pom in order to use log4j2 with slf4j1x ? Technically log4j-slf4j-impl is just a bridge between SLF4J and Log4j API. You also should add a Log4j API implementation (e.g. log4j-core).
Log4j 2 is actively maintained and releases on almost regular schedule. It also includes lot of modern features and -imho- makes a couple of things better than Logback.
However, log4j 1.x comes with JMSAppender which will perform a JNDI lookup if enabled in log4j's configuration file, i.e. log4j.properties or log4j.xml. An attacker who ALREADY has write access the log4j configuration file will need to add JMSAppender into the configuration poisoned with malicious connection parameters.
The snippet below could be added to the file above with the log4j tags. This logger would inherit the appenders from <root> but would limit the all logging events from the package org.springframework to those logged at level info or above.
Conversely, if you're logging with Log4j 1.2 directly (without SLF4J) and need to call a library that's using SLF4J, you're going to want to include the slf4j-log4j12 library to intercept those calls and translate them to Log4j for you.
What is the hierarchy of log4j logging? DEBUG INFO WARN ERROR FATAL Which one provides the highest logging which would be helpful to troubleshoot issues? Can any one provide the order or hierarchy...
Log4j and SLF4J+Logback are comparable, but while Log4j is one solution, I would consider Logback and SLF4J as highly complementary products. Unlike Log4j, SLF4J for instance features slf4j-simple, which allows to use it alone, without Logback.
