log4j.appender.console.layout=org.apache.log4j.PatternLayout log4j.appender.console.layout.ConversionPattern=%d{yyyy-MM-dd HH:mm:ss} %p [%t] %c - %m%n log4j.rootLogger=INFO, console log4j.logger.com.example=INFO import org.apache.log4j.Logger; public class MyClass { private static final Logger logger = Logger.getLogger(MyClass.class); public void doSomething() { logger.debug("DEBUG message"); logger.info("INFO message"); logger.warn("WARN message"); logger.error("ERROR message"); } } import org.apache.log4j.Logger; import org.apache.log4j.MDC; public class MyClass { private static final Logger logger = Logger.getLogger(MyClass.class); public void doSomething() { MDC.put("username", "Alice"); logger.info("User action performed"); MDC.remove("username"); } }