Question

I have a Java web application that uses the SLF4J logging facade. To date, we use the Log4J implementation underneath (though we are considering a switch to Logback). Log4J is currently configured via a log4j.xml configuration file that is placed in the root of our classpath.

In any event, we use JNDI to configure other aspects of our application so I am very familiar with how to set that up and pull a string from JNDI into a Spring configuration file.

However, I am at a loss to figure out how to create a Log4J appender from within a Spring configuration file. Better yet, can one completely configure Log4J via Spring and skip the log4j.xml configuration file altogether? I am hoping I don’t have to do this programmatically.

I found a Spring class called Log4jWebConfigurer but this requires that the WAR run exploded (don’t want that if I can help it) and also that the log file resides within the web-app directory (definitely don’t want that).

Answer 1

First get the main directory via JNDI:

<jee:jndi-lookup id="myAppHome" jndi-name="myAppHome" />

Then use that bean in a Spring Expression Language statement in the the following way:

<bean id="log4jInitialization" class="org.springframework.beans.factory.config.MethodInvokingFactoryBean">
    <property name="targetClass" value="org.springframework.util.Log4jConfigurer" />
    <property name="targetMethod" value="initLogging" />
    <property name="arguments">
        <list>
            <value>#{ myAppHome + '/conf/log4j.xml'}</value>
        </list>
    </property>
</bean>