import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; public class MyLibraryClass { private static final Log log = LogFactory.getLog(MyLibraryClass.class); // ... } public class MyLibraryClass { private static final Log log = LogFactory.getLog(MyLibraryClass.class); public void doSomething() { log.debug("Doing something..."); // ... } } org.apache.commons.logging.Log=org.apache.commons.logging.impl.Log4JLogger import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; public class MyLibraryClass { private static final Log log = LogFactory.getLog(MyLibraryClass.class); public void doSomething() { log.debug("Doing something..."); // ... } // ... } org.apache.commons.logging.Log=org.apache.commons.logging.impl.Log4JLogger