Apache log4j, a classic logging tool in Java. Below are a series of Log4j 1.2 tutorials :

Log4j Tutorials

• Log4j hello world example
  A simple Log4j hello world example, a quick start guide.
• log4j.properties Example
  Log4j configuration in properties file format.
• log4j.xml example
  Log4j configuration in XML file format.
• Spring MVC + Log4j integration example
  Enable log4j logging in Spring MVC framework.
• Struts 2 + Log4j Integration Example
  Enable log4j logging in Struts 2 framework.
• Struts 1 + Log4j integration example
  Enable log4j logging in Struts 1 framework.
• JSF 2 + Log4j Integration Example
  Enable log4j logging in JSF 2 framework. Example to use slf4j bridge handler, to redirect logging from java.util.logging to log4j.
• Wicket + Log4j Integration Example
  Enable log4j logging in Wicket framework. Wicket uses slf4j, need slf4j-log4j12

References

1. Log4j 1.2 Official Page
2. Wikipedia : Log4j