Log4j2 LevelRangeFilter Example

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 info level logs will go to application-info.log file.
• All debug level logs will go to application-debug.log file.
• All error level logs will go to application-error.log file.

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 !!