logging-fwk-comp.md

Java Logging Frameworks Overview

Main frameworks

• JDK Logging (JUL : java.util.logging)
• Log4J 1.X
• Log4J 2.X
• Apache Commons-logging (JCL)
• SLF4J

ℹ️ Logback is the reference implementation for SLF4J

ℹ️ Spring Framework historically use commons-logging

Loggers

Implementation classes

Framework	Class name
JDK Logging	java.util.logging.Logger
Log4J 1	org.apache.log4j.Logger
Log4J 2	org.apache.logging.log4j.Logger
Commons-Logging	org.apache.commons.logging.Log
SLF4J	org.slf4j.Logger
Logback	ch.qos.logback.classic.Logger

ℹ️ Note the Commons-Logging singularity

Obtain a Logger instance

Framework	Package	From name	From class
JDK Logging	java.util.logging	Logger.getLogger("name")	🚫
Log4J 1	org.apache.log4j	Logger.getLogger("name")	Logger.getLogger(clazz)
Log4J 2	org.apache.logging.log4j	LogManager.getLogger("name")	LogManager.getLogger(clazz)
Commons-Logging	org.apache.commons.logging	LogFactory.getLog("name")	LogFactory.getLog(clazz)
SLF4J	org.slf4j	LoggerFactory.getLogger("name")	LoggerFactory.getLogger(clazz)

Trace Methods

JDK Logging	Log4J 1	Log4J 2	Commons-Logging	SLF4J
finest()	trace()	trace()	trace()	trace()
finer()	🚫	🚫	🚫	🚫
fine()	debug()	debug()	debug()	debug()
config()	🚫	🚫	🚫	🚫
info()	info()	info()	info()	info()
warning()	warn()	warn()	warn()	warn()
🚫	error()	error()	error()	error()
severe()	fatal()	fatal()	fatal()	🚫
log()	log()	log()	🚫	🚫

ℹ️ Logback/SLF4J does not have a FATAL level

Levels

Implementation classes

Framework	Class name
JDK Logging	java.util.logging.Level
Log4J 1	org.apache.log4j.Level
Log4J 2	org.apache.logging.log4j.Level
Commons-Logging	🚫
SLF4J	org.slf4j.event.Level
Logback	ch.qos.logback.classic.Level

Effectives levels

JDK Logging	Log4J 1	Log4J 2	Commons-Logging	SLF4J
ALL	ALL	ALL	🚫	🚫
FINEST	TRACE	TRACE	TRACE	TRACE
FINER	🚫	🚫	🚫	🚫
FINE	DEBUG	DEBUG	DEBUG	DEBUG
CONFIG	🚫	🚫	🚫	🚫
INFO	INFO	INFO	INFO	INFO
WARNING	WARN	WARN	WARN	WARN
🚫	ERROR	ERROR	ERROR	ERROR
SEVERE	FATAL	FATAL	FATAL	🚫
OFF	OFF	OFF	🚫	🚫

IsEnabled Methods

JDK Logging	Log4J 1	Log4J 2	Commons-Logging	SLF4J
isLoggable(Level)	isEnabledFor(Priority)	isEnabled(Level)	🚫	🚫
🚫	isTraceEnabled()	isTraceEnabled()	isTraceEnabled()	isTraceEnabled()
🚫	isDebugEnabled()	isDebugEnabled()	isDebugEnabled()	isDebugEnabled()
🚫	isInfoEnabled()	isInfoEnabled()	isInfoEnabled()	isInfoEnabled()
🚫	🚫	isWarnEnabled()	isWarnEnabled()	isWarnEnabled()
🚫	🚫	isErrorEnabled()	isErrorEnabled()	isErrorEnabled()
🚫	🚫	isFatalEnabled()	isFatalEnabled()	🚫

Context

JDK Logging	Log4J 1	Log4J 2	Commons-Logging	SLF4J
🚫	NDC	ThreadContext	🚫	:no_entry_sign:
🚫	MDC	ThreadContext	🚫	MDC

Links

Official pages

• SLF4J
• Logback - Configuration
• Log4J 1.2
• Log4J 2 - Manual
• Apache Commons - commons-logging
• Java Logging Overview

Tutorials

• Baeldung - Introduction to Java Logging
• Baeldung - Java Logging with Nested Diagnostic Context (NDC)
• Spring - Spring Boot Logging