It's loaded via the ServiceLoader interface: https://github.com/apache/logging-log4j2/blob/master/log4j-jcl/src/main/resources/META-INF/services/org.apache.commons.logging.LogFactory
On 5 July 2017 at 03:30, Asma Zinneera Jabir <azinne...@gmail.com> wrote: > I am trying to set up log4j2 for Apache Commons Logging using the > *commons-logging.properties* file in an OSGi environment. For Log4j 1 I > could use org.apache.commons.logging.Log=org.apache.commons.logging.impl. > Log4JLogger which maps to version Log4j 1.2. I couldn't find out the > implementation for log4J2. The version I am using is 2.8.2. > > There is a central logging component which is referred by other components > and this component bundles other needed loggers (e.g. commons-logging, > log4j/log4j2) added as dependencies. > > The Log4J2 documentation for Log4J Commons Logging Bridge > <https://logging.apache.org/log4j/log4j-2.3/log4j-jcl/index.html> > specifies > that by just *adding the bridge jar along with the other Log4j 2 jars and > the Commons Logging jar, all logging done using the Commons Logging API > will be routed to Log4*. I tried this by adding > > - log4j-api > - log4j-core > - log4j-jcl > - commons-logging > > dependencies in the *pom.xml* of the central logging component and bundled > with it without (and with just to check) using the > *commons-logging.properties* but didn't work that way. How can I implement > this with or without the commons-logging.properties? > > I debugged the commons-logging source code and found in > LogFactoryImpl.java it > looks for a logging implementation (L843 > <https://github.com/apache/commons-logging/blob/LOGGING_ > 1_2/src/main/java/org/apache/commons/logging/impl/LogFactoryImpl.java#L843 > >) > from a list (L162 > <https://github.com/apache/commons-logging/blob/LOGGING_ > 1_2/src/main/java/org/apache/commons/logging/impl/LogFactoryImpl.java#L162 > >). > Here since the Log4JLogger does not support Log4J2 it then sets to the next > in line, that is JDK14Logger. Since the Log4J2 documentaiton says adding > the bridge simply maps the logs from JCL to Log4J2, what role does the > bridging api play here? I noticed the LogFactoryImpl.java and > Log4JLog.java in > it but how does commons-logging refer to these which are in a different > package? > > stackoverflow question: Apache commons-logging bridge for log4j2 > <https://stackoverflow.com/questions/44839779/apache- > commons-logging-bridge-for-log4j2> > -- Matt Sicker <boa...@gmail.com>
