Log4j using properties file.

Please follow the following program to understand log4j implementation.

Here I have used console appender to log the events.

Java File: PropertyConfiguratorDemo

import org.apache.log4j.Logger;

import org.apache.log4j.PropertyConfigurator;

public class PropertyConfiguratorDemo {

      private static final Logger logger = Logger.getLogger(PropertyConfiguratorDemo.class);

      public static void main(String[] args) {

            PropertyConfigurator.configure("log.properties");

            logger.trace("Trace Message.");//Point to Point.

            logger.debug("Debug Message.");//Method to Method.         

            logger.info("Info Message.");//Information passing and recieving.

            logger.warn("Warning Message.");//Retrying again.

            logger.error("Error Message.");//Error occured and can continue further.

            logger.fatal("Fatal Message.");//Error occured and needs to stop application.

      }

}

Properties File: log.properties

log4j.rootLogger=DEBUG, Console

log4j.appender.Console=org.apache.log4j.ConsoleAppender

log4j.appender.Console.layout=org.apache.log4j.PatternLayout

log4j.appender.Console.layout.ConversionPattern=%d %p %c --> %M - %m%n

Output:

2012-05-31 16:19:36,781 DEBUG com.lenin.log4j.PropertyConfiguratorDemo --> main - Debug Message.

2012-05-31 16:19:36,781 INFO com.lenin.log4j.PropertyConfiguratorDemo --> main - Info Message.

2012-05-31 16:19:36,781 WARN com.lenin.log4j.PropertyConfiguratorDemo --> main - Warning Message.

2012-05-31 16:19:36,781 ERROR com.lenin.log4j.PropertyConfiguratorDemo --> main - Error Message.

2012-05-31 16:19:36,781 FATAL com.lenin.log4j.PropertyConfiguratorDemo --> main - Fatal Message.