1、tomcat的安装路径下tomcat home下的common文件夹下的classes文件夹中创建log4j.properties文件，即 apache-tomcat-5.5.20\common\classes

log4j.rootLogger=info,Console,R

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

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

#log4j.appender.Console.layout.ConversionPattern=%d [%t] %-5p %c - %m%n

log4j.appender.Console.layout.ConversionPattern=%d{yy-MM-dd HH:mm:ss} %5p %c{1}:%L - %m%n

log4j.appender.R=org.apache.log4j.DailyRollingFileAppender

log4j.appender.R.File=${catalina.home}/logs/tomcat.log

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

log4j.appender.R.layout.ConversionPattern=%d{yyyy.MM.dd HH:mm:ss} %5p %c{1}(%L):? %m%n

log4j.logger.org.apache=info,R

log4j.logger.org.apache.catalina.core.ContainerBase.[Catalina].[localhost]=DEBUG, R

log4j.logger.org.apache.catalina.core=info,R

log4j.logger.org.apache.catalina.session=info,R

2、将log4j-1.2.15.jar和commons-logging.jar包拷贝到Tomcat 5.5.20/common/lib下即可