在编译好的环境下 即tomcat/webapp/ROOT/WEB-INF/classes中加入system-ext.properties
其内容如下：
##
## Logging
##
#
# Set any logger that implements org.apache.commons.logging.Log.
#
org.apache.commons.logging.Log=org.apache.commons.logging.impl.Log4JLogger
#
# Set this to true if Log4j complains that it was not properly configured.
#
log4j.configure.on.startup=false
再在该目录下加入自己定义的log4j.properties 即可
参考http://issues.liferay.com/browse/LPS-7719