[jboss-jira] [JBoss JIRA] (JBLOGGING-94) JBoss Logging does not detect log4j 2.0

[Henry Clout (JIRA)]

Henry Clout created JBLOGGING-94:
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             Summary: JBoss Logging does not detect log4j 2.0
                 Key: JBLOGGING-94
                 URL: https://issues.jboss.org/browse/JBLOGGING-94
             Project: JBoss Logging
          Issue Type: Bug
      Security Level: Public (Everyone can see)
          Components: jboss-logging-log4j
    Affects Versions: 3.1.2.GA
         Environment: Hibernate 
            Reporter: Henry Clout
            Assignee: David Lloyd


The class org.jboss.logging.LoggerProviders checkes for the presence of log4j using the code:

    private static LoggerProvider tryLog4j(final ClassLoader cl) throws ClassNotFoundException {
        Class.forName("org.apache.log4j.LogManager", true, cl);
        // JBLOGGING-65 - slf4j can disguise itself as log4j.  Test for a class that slf4j doesn't provide.
        Class.forName("org.apache.log4j.Hierarchy", true, cl);
        return new Log4jLoggerProvider();
    }

However, despite having the log4j-1.2-api-2.0.jar bridge included, this fails as the class org.apache.log4j.Hierarchy is not present in log4j 2.0.

I worked around this by forcing JBoss logging to use slf4j (which is then proxied to log4j) by setting the -Dorg.jboss.logging.provider=slf4j option.  

As a proper fix, however, how about checking for a class that is included in log4j 1.2, 2.0 but not slf4j? org.apache.log4j.config.PropertySetter seems to tick the box.

I tested changing the afore mentioned method to:

    private static LoggerProvider tryLog4j(final ClassLoader cl) throws ClassNotFoundException {
        Class.forName("org.apache.log4j.LogManager", true, cl);
        // JBLOGGING-65 - slf4j can disguise itself as log4j.  Test for a class that slf4j doesn't provide.
        Class.forName("org.apache.log4j.config.PropertySetter", true, cl);
        return new Log4jLoggerProvider();
    }

And indeed I started receiving logging messages from Hibernate (via JBoss logging.)

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