configuration

Log4j property file

Below is a configuration file for log4j. Log4j2 can use the same syntax, but there are different appender classes:

log4j.rootLogger=INFO, FOO

## ConsoleAppender
log4j.appender.CA=org.apache.log4j.ConsoleAppender
log4j.appender.CA.layout=org.apache.log4j.PatternLayout
log4j.appender.CA.layout.ConversionPattern= %d{hh:mm:ss,SSS} [%t] %-5p %c %x - %m%n

## FileAppender
log4j.appender.FOO=org.apache.log4j.RollingFileAppender
log4j.appender.FOO.File=${catalina.home}/logs/app.log
log4j.appender.FOO.Append=true
log4j.appender.FOO.layout=org.apache.log4j.PatternLayout
log4j.appender.FOO.layout.ConversionPattern= %d{hh:mm:ss,SSS} [%t] %-5p %c %x - %m%n

## attaching appender to specific package:
log4j.logger.com.example.package=INFO, CA

Directive log4j.rootLogger defines log level and appender for any class that doesn’t meet logger criteria. Notice that appender name is defined after word ‘appender’.

Resolve run time issue with log4j configuration

Users may face the following issue:

 log4j:WARN No appenders could be found for logger (dao.hsqlmanager).
 log4j:WARN Please initialize the log4j system properly.
 log4j:WARN See https://logging.apache.org/log4j/1.2/faq.html#noconfig for more info.

One reason this can occur is if the log4j.properties or .xml file is not located within the project itself. (This can happen when you ship a tool, where the tool/JAR is in one directory and all the configuration is another directory).

You will then need to specify the path to the log4j.properties or .xml file. In the command line utility,

java -Dlog4j.configuration=file:///path/To/log4j.properties YourProject.jar

or if you have a script to run the tool you can add

-Dlog4j.configuration=file:///path/To/log4j.properties

to the place where you do the equivalent action of the command line version. Not that log4j.configuration is specified in a URL format, prefixed by file:///.