Shunting certain org.apache.log4j log messages off to a particular log file

Question

We already have extensive logging in our application using org.apache.log4j. We now want to shunt some of these messages off to a new XML log file (while continuing to go to the original log file).

Is this possible? Is there a way we can identify these messages and send them someplace special in addition to the regular log file?

Answer 1

I think you can define two file appenders. One at the root level and other at the package(select the package level as appropriate) level as below:

# Root logger option
log4j.rootLogger=DEBUG, RootFileAppender

#Shunted Logger option
log4j.logger.com.shunted=ERROR,ShuntedFileAppender


# RootFileAppender - used to log messages in the root.log file.
log4j.appender.RootFileAppender=org.apache.log4j.FileAppender
log4j.appender.RootFileAppender.File=root.log
log4j.appender.RootFileAppender.MaxFileSize=100MB
log4j.appender.RootFileAppender.layout=org.apache.log4j.PatternLayout
log4j.appender.RootFileAppender.layout.ConversionPattern= %5p [%t] (%F:%L) - %m%n


# ShuntedFileAppender - used to log messages in the shunted.log file.
log4j.appender.ShuntedFileAppender=org.apache.log4j.FileAppender
log4j.appender.ShuntedFileAppender.File=shunted.log
log4j.appender.ShuntedFileAppender.MaxFileSize=10MB
log4j.appender.ShuntedFileAppender.layout=org.apache.log4j.PatternLayout
log4j.appender.ShuntedFileAppender.layout.ConversionPattern= %5p [%t] (%F:%L) - %m%n

Please Note: You can define the two logger option as different levels as well. In above example, ROOT is defined at DEBUG while shunted is devined as ERROR level.