Apache Log4j2 is an upgrade to Log4j 1.x that provides significant improvements over its predecessor. This page list down various hello world configuration examples and useful tutorials for working with Log4j2.
1. Log4j2 Maven Dependencies
To include Log4j2, include below maven dependencies.
<dependency> <groupId>org.apache.logging.log4j</groupId> <artifactId>log4j-core</artifactId> <version>2.20.0</version> </dependency> <dependency> <groupId>org.apache.logging.log4j</groupId> <artifactId>log4j-api</artifactId> <version>2.20.0</version> </dependency>Gradle dependecies are:
implementation group: 'org.apache.logging.log4j', name: 'log4j-core', version: '2.20.0' implementation group: 'org.apache.logging.log4j', name: 'log4j-api', version: '2.20.0'Read More : Log4j2 with SLF4j Configuration
2. Log4j2 XML Configuration Example
A sample log4j2.xml configuration file for reference.
<?xml version="1.0" encoding="UTF-8"?> <Configuration status="WARN" monitorInterval="30"> <!-- Logging Properties --> <Properties> <Property name="LOG_PATTERN">%d{yyyy-MM-dd'T'HH:mm:ss.SSSZ} %p %m%n</Property> <Property name="APP_LOG_ROOT">c:/temp</Property> </Properties> <Appenders> <!-- Console Appender --> <Console name="Console" target="SYSTEM_OUT" follow="true"> <PatternLayout pattern="${LOG_PATTERN}"/> </Console> <!-- File Appenders on need basis --> <RollingFile name="frameworkLog" fileName="${APP_LOG_ROOT}/app-framework.log" filePattern="${APP_LOG_ROOT}/app-framework-%d{yyyy-MM-dd}-%i.log"> <LevelRangeFilter minLevel="ERROR" maxLevel="ERROR" onMatch="ACCEPT" onMismatch="DENY"/> <PatternLayout pattern="${LOG_PATTERN}"/> <Policies> <SizeBasedTriggeringPolicy size="19500KB" /> </Policies> <DefaultRolloverStrategy max="10"/> </RollingFile> <RollingFile name="debugLog" fileName="${APP_LOG_ROOT}/app-debug.log" filePattern="${APP_LOG_ROOT}/app-debug-%d{yyyy-MM-dd}-%i.log"> <LevelRangeFilter minLevel="DEBUG" maxLevel="DEBUG" onMatch="ACCEPT" onMismatch="DENY"/> <PatternLayout pattern="${LOG_PATTERN}"/> <Policies> <SizeBasedTriggeringPolicy size="19500KB" /> </Policies> <DefaultRolloverStrategy max="10"/> </RollingFile> <RollingFile name="infoLog" fileName="${APP_LOG_ROOT}/app-info.log" filePattern="${APP_LOG_ROOT}/app-info-%d{yyyy-MM-dd}-%i.log" > <LevelRangeFilter minLevel="INFO" maxLevel="INFO" onMatch="ACCEPT" onMismatch="DENY"/> <PatternLayout pattern="${LOG_PATTERN}"/> <Policies> <SizeBasedTriggeringPolicy size="19500KB" /> </Policies> <DefaultRolloverStrategy max="10"/> </RollingFile> <RollingFile name="errorLog" fileName="${APP_LOG_ROOT}/app-error.log" filePattern="${APP_LOG_ROOT}/app-error-%d{yyyy-MM-dd}-%i.log" > <LevelRangeFilter minLevel="ERROR" maxLevel="ERROR" onMatch="ACCEPT" onMismatch="DENY"/> <PatternLayout pattern="${LOG_PATTERN}"/> <Policies> <SizeBasedTriggeringPolicy size="19500KB" /> </Policies> <DefaultRolloverStrategy max="10"/> </RollingFile> <RollingFile name="perfLog" fileName="${APP_LOG_ROOT}/app-perf.log" filePattern="${APP_LOG_ROOT}/app-perf-%d{yyyy-MM-dd}-%i.log" > <PatternLayout pattern="${LOG_PATTERN}"/> <Policies> <SizeBasedTriggeringPolicy size="19500KB" /> </Policies> <DefaultRolloverStrategy max="1"/> </RollingFile> <RollingFile name="traceLog" fileName="${APP_LOG_ROOT}/app-trace.log" filePattern="${APP_LOG_ROOT}/app-trace-%d{yyyy-MM-dd}-%i.log" > <PatternLayout pattern="${LOG_PATTERN}"/> <Policies> <SizeBasedTriggeringPolicy size="19500KB" /> </Policies> <DefaultRolloverStrategy max="1"/> </RollingFile> </Appenders> <Loggers> <Logger name="com.howtodoinjava.app.somePackage" additivity="false" level="trace"> <AppenderRef ref="traceLog" /> <AppenderRef ref="Console" /> </Logger> <Logger name="com.howtodoinjava.app" additivity="false" level="debug"> <AppenderRef ref="debugLog" /> <AppenderRef ref="infoLog" /> <AppenderRef ref="errorLog" /> <AppenderRef ref="Console" /> </Logger> <Logger name="org.framework.package" additivity="false" level="info"> <AppenderRef ref="perfLog" /> <AppenderRef ref="Console"/> </Logger> <Root level="warn"> <AppenderRef ref="Console"/> </Root> </Loggers> </Configuration>3. Log4j2 Properties Configuration Example
A sample log4j2.properties file for reference.
status = warn name = PropertiesConfig #Make sure to change the log file path as per your need property.filename = C:\\logs\\debug.log filters = threshold filter.threshold.type = ThresholdFilter filter.threshold.level = debug appenders = console appender.console.type = Console appender.console.name = STDOUT appender.console.layout.type = PatternLayout appender.console.layout.pattern = %d{yyyy-MM-dd HH:mm:ss} %-5p %c{1}:%L - %m%n appenders = rolling appender.rolling.type = RollingFile appender.rolling.name = RollingFile appender.rolling.fileName = ${filename} appender.rolling.filePattern = debug-backup-%d{MM-dd-yy-HH-mm-ss}-%i.log.gz appender.rolling.layout.type = PatternLayout appender.rolling.layout.pattern = %d{yyyy-MM-dd HH:mm:ss} %-5p %c{1}:%L - %m%n appender.rolling.policies.type = Policies appender.rolling.policies.time.type = TimeBasedTriggeringPolicy appender.rolling.policies.time.interval = 1 appender.rolling.policies.time.modulate = true appender.rolling.policies.size.type = SizeBasedTriggeringPolicy appender.rolling.policies.size.size=10MB appender.rolling.strategy.type = DefaultRolloverStrategy appender.rolling.strategy.max = 20 loggers = console, rolling #Make sure to change the package structure as per your application logger.rolling.name = com.howtodoinjava logger.rolling.level = debug logger.rolling.additivity = false logger.rolling.appenderRef.rolling.ref = RollingFile4. Log4j2 Examples
- Log4j2 ConsoleAppender Example
- Log4j2 RollingFileAppender Example
- Log4j2 JDBCAppender Example
- Log4j2 LevelRangeFilter Example
- Log4j2 Multiple appenders Example
- Log4j2 HTMLLayout Configuration Example
- Log4j2 ThreadContext – Fish Tagging Logs of Same Transaction
- Log4j2 – Useful Conversion Pattern Examples
- Configure Log4j2 for JUnit Testcases
- Log4j2 JSON Configuration Example
- Log4j2 Properties File Example
- Log4j2 XML Configuration Example
- Filter Messages using MarkerFilter
Happy Learning !!
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