Logging framework - SLF4J (Simple Logging Facade for Java)

Maven dependency (version managed by related BoM maven project pom.xml)

<dependency>
	<groupId>org.slf4j</groupId>
	<artifactId>slf4j-api</artifactId>
</dependency>	

How to use

// import required classes
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
 
// define logger
private static final Logger LOGGER = LoggerFactory.getLogger(AuthenticationServiceImpl.class);
 
// use in code
try {
// logic
} catch (final StorageException e) {
	final String message = "(" + accountId + ") fail.";
	LOGGER.error(message, e);
	throw new AuthenticationServiceException(message, e);
}

FATAL logging level (marker usage example)

// import utility
import net.bolbat.utils.logging.LoggingUtils;
 
// use in code
try {
// logic
} catch (final ManagerException e) {
	final String message = "Can't initialize persistence service.";
	LOGGER.error(LoggingUtils.FATAL, message, e);
	throw new ServiceInstantiationException(message, e);
}

SLF4J API implementations

• default no-operation (NOP) logger, included in slf4j-api

• logback (version managed by our maven parent project pom.xml)

  <dependency> <groupId>ch.qos.logback</groupId> <artifactId>logback-classic</artifactId> </dependency>

• apache log4j (version managed by our maven parent project pom.xml)

  <dependency> <groupId>org.slf4j</groupId> <artifactId>slf4j-log4j12</artifactId> </dependency>

• apache commons-logging (version managed by our maven parent project pom.xml) 

  <dependency> <groupId>org.slf4j</groupId> <artifactId>slf4j-jcl</artifactId> </dependency>

• java util logging (version managed by our maven parent project pom.xml) 

  <dependency> <groupId>org.slf4j</groupId> <artifactId>slf4j-jdk14</artifactId> </dependency>

How to use for JUnit's without real dependency to logger implementation (logback example)

• Add maven dependency only for testing scope (version managed by our maven parent project pom.xml) 

  <dependency> <groupId>ch.qos.logback</groupId> <artifactId>logback-classic</artifactId> <scope>test</scope> </dependency>

• Configure logger (example configuration)

Logging redirection from other loggers to SLF4J (just add required dependency)

• apache log4j 

  <dependency> <groupId>org.slf4j</groupId> <artifactId>log4j-over-slf4j</artifactId> <version>1.7.5</version> </dependency>

• apache commons-logging 

  <dependency> <groupId>org.slf4j</groupId> <artifactId>jcl-over-slf4j</artifactId> <version>1.7.5</version> </dependency>

• java util logging 

  <dependency> <groupId>org.slf4j</groupId> <artifactId>jul-to-slf4j</artifactId> <version>1.7.5</version> </dependency>

• details can be found on http://www.slf4j.org/legacy.html