How to configurate Log4j for Tomcat 7 internal loger

1. Create a file called log4j.properties with the following content:
log4j.rootLogger=INFO, Console
log4j.appender.Console=org.apache.log4j.RollingFileAppender
log4j.appender.Console.File=${catalina.base}/logs/tomcat.log
log4j.appender.Console.MaxFileSize=100MB
log4j.appender.Console.MaxBackupIndex=10
log4j.appender.Console.layout=org.apache.log4j.PatternLayout
log4j.appender.Console.layout.ConversionPattern=%p %t %c - %m%n

Place this file in Tomcat_home/lib.

2. Download log4j.xx.jar to Tomcat_home/lib
3. Download output/extras/tomcat-juli.jar to replace the old same file in Tomcat_home/bin.
4. Download tomcat-juli-adapters.jar to place in Tomcat_home/lib.
5. Delete $CATALINA_BASE/conf/logging.properties.
6. Start Tomcat.

Tomcat will use log4j rather than java.util.logging for all Tomcat's internal logging.