Spring boot’s default logging uses Logback which is included as a transitive dependency. Spring Boot supports Log4j2 for logging configuration if it is on the classpath and Logback is excluded.
To configure Log4j2 with Spring Boot2, follow these two simple steps:
1. Log4j2 Maven Dependency
In fact, it is two steps change. First, remove spring’s default spring-boot-starter-logging starter dependency which excludes Logback from the classpath. Then add the spring-boot-starter-log4j2 starter dependency.
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
<exclusions>
<exclusion>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-logging</artifactId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-log4j2</artifactId>
</dependency>
</dependencies>
2. Add log4j2.xml File in /resources Folder
Spring will automatically configure log4j2 once it finds its jar files in the classpath. Now we have to add log4j2.xml
or (log4j2.properties
) in src/main/resources
folder. That’s all.
<?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>
<Property name="APP_LOG_ROOT">c:/temp</Property>
</Properties>
<Appenders>
<Console name="Console" target="SYSTEM_OUT" follow="true">
<PatternLayout pattern="${LOG_PATTERN}" />
</Console>
<RollingFile name="appLog"
fileName="${APP_LOG_ROOT}/SpringBoot2App/application.log"
filePattern="${APP_LOG_ROOT}/SpringBoot2App/application-%d{yyyy-MM-dd}-%i.log">
<PatternLayout pattern="${LOG_PATTERN}" />
<Policies>
<SizeBasedTriggeringPolicy size="19500KB" />
</Policies>
<DefaultRolloverStrategy max="1" />
</RollingFile>
</Appenders>
<Loggers>
<Logger name="com.howtodoinjava.app" additivity="false">
<AppenderRef ref="appLog" />
<AppenderRef ref="Console" />
</Logger>
<Root level="debug">
<AppenderRef ref="Console" />
<AppenderRef ref="appLog" />
</Root>
</Loggers>
</Configuration>
3. Demo
Now add a few log statements in the application and see the logs in configured appenders e.g. I configured console and file.
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.support.SpringBootServletInitializer;
import org.springframework.context.ApplicationContext;
@SpringBootApplication
public class Application extends SpringBootServletInitializer {
private static final Logger LOGGER = LogManager.getLogger(Application.class);
public static void main(String[] args)
{
ApplicationContext ctx = SpringApplication.run(Application.class, args);
LOGGER.info("Info level log message");
LOGGER.debug("Debug level log message");
LOGGER.error("Error level log message");
}
}
Check the output in the console and the log file.
2018-06-01T13:55:42.506+0530 INFO Info level log message
2018-06-01T13:55:42.506+0530 DEBUG Debug level log message
2018-06-01T13:55:42.506+0530 ERROR Error level log message
Let me know if you face any problems in this spring boot log4j2 example.
Happy Learning !!
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