Learn to use log4j LevelRangeFilter filter which returns the onMatch result if the level in the LogEvent is in the range of the configured min and max levels, otherwise it returns onMismatch value.
LevelRangeFilter Configuration
In given log4j2.xml file, we have used to LevelRangeFilter to filter log levels in such a way that :
- All
infolevel logs will go toapplication-info.logfile. - All
debuglevel logs will go toapplication-debug.logfile. - All
errorlevel logs will go toapplication-error.logfile.
Feel free to change the minLevel and maxLevel attributes according to the project needs.
<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="WARN" monitorInterval="30">
<Properties>
<Property name="LOG_PATTERN">%d{yyyy-MM-dd'T'HH:mm:ss.SSSZ} %p %m%n</Property>
</Properties>
<Appenders>
<Console name="Console" target="SYSTEM_OUT" follow="true">
<PatternLayout pattern="${LOG_PATTERN}"/>
</Console>
<RollingFile name="debugLog" fileName="${sys:APP_LOG_ROOT}/application-debug.log"
filePattern="${sys:APP_LOG_ROOT}/application-debug-%d{yyyy-MM-dd}-%i.log">
<!-- Matches only DEBUG level -->
<LevelRangeFilter minLevel="DEBUG" maxLevel="DEBUG" onMatch="ACCEPT" onMismatch="DENY"/>
<PatternLayout pattern="${LOG_PATTERN}"/>
<Policies>
<SizeBasedTriggeringPolicy size="19500KB" />
</Policies>
<DefaultRolloverStrategy max="10"/>
</RollingFile>
<RollingFile name="infoLog" fileName="${sys:APP_LOG_ROOT}/application-info.log"
filePattern="${sys:APP_LOG_ROOT}/application-info-%d{yyyy-MM-dd}-%i.log" >
<!-- Matches only INFO level -->
<LevelRangeFilter minLevel="INFO" maxLevel="INFO" onMatch="ACCEPT" onMismatch="DENY"/>
<PatternLayout pattern="${LOG_PATTERN}"/>
<Policies>
<SizeBasedTriggeringPolicy size="19500KB" />
</Policies>
<DefaultRolloverStrategy max="10"/>
</RollingFile>
<RollingFile name="errorLog" fileName="${sys:APP_LOG_ROOT}/application-error.log"
filePattern="${sys:APP_LOG_ROOT}/application-error-%d{yyyy-MM-dd}-%i.log">
<!-- Matches only ERROR level -->
<LevelRangeFilter minLevel="ERROR" maxLevel="ERROR" onMatch="ACCEPT" onMismatch="DENY"/>
<PatternLayout pattern="${LOG_PATTERN}"/>
<Policies>
<SizeBasedTriggeringPolicy size="19500KB" />
</Policies>
<DefaultRolloverStrategy max="10"/>
</RollingFile>
</Appenders>
<Loggers>
<Logger name="com.howtodoinjava.app" additivity="false">
<AppenderRef ref="debugLog" />
<AppenderRef ref="infoLog" />
<AppenderRef ref="errorLog" />
<AppenderRef ref="Console" />
</Logger>
<Root level="all">
<AppenderRef ref="Console"/>
</Root>
</Loggers>
</Configuration>
Drop me your questions in comments section.
Happy Learning !!
Can you please explain additivity property?
Additivity determines whether a logger passes its log messages to its parent logger. When it is true, logger will pass its log messages to its own appenders and to those of its parent logger(s). If “com.example” logger and its parent “com” logger both have a console appender, a log message from “com.example” will be printed twice—once by “com.example” and once by “com”.
When set to false, logger will not pass its log messages to its parent logger(s). So, in previous example, a log message from “com.example” will only be printed once by “com.example” and not by any parent logger.
Additivity is used for avoiding the duplicate logs in multiple log files. In this example, additivity does not make such difference because there is only one logger.