Apache Commons Logging tutorial

Commons Logging library acts as a bridge between different logging implementations (Ex: log4j, jdk14logger, simple logger). By using commons-logging, you can change the underlying application logging implementation without recompiling code. For example, assume you are using jdk14 logger right now, you can switch to log4j without recompiling the application.

Hello World Application

Step 1: Create new maven project in Eclipse.

Open Eclipse, right click on 'Project Explorer' -> New -> Other.

Search for ‘Maven’.

Select ‘Maven Project’ and click on Next button.

Select the check box ‘Create a simple project (skip archetype selection), and click on Next button.

Give the group id, artifact id as 'commonsLoggingDemo' and set the version to 1.

Click on Finish button.

Project structure is created like below.

Step 2: Update pom.xml with maven dependencies.

pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0"
 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
 <modelVersion>4.0.0</modelVersion>
 <groupId>commonsLoggingDemo</groupId>
 <artifactId>commonsLoggingDemo</artifactId>
 <version>1</version>

 <dependencies>
  <!-- https://mvnrepository.com/artifact/commons-logging/commons-logging -->
  <dependency>
   <groupId>commons-logging</groupId>
   <artifactId>commons-logging</artifactId>
   <version>1.2</version>
  </dependency>

  <!-- https://mvnrepository.com/artifact/log4j/log4j -->
  <dependency>
   <groupId>log4j</groupId>
   <artifactId>log4j</artifactId>
   <version>1.2.17</version>
  </dependency>

 </dependencies>
</project>

Step 3: Create a file 'commons-logging.properties' under src/main/resources.

commons-logging.properties

org.apache.commons.logging.Log=org.apache.commons.logging.impl.Log4JLogger
 
log4j.configuration=log4j.properties

Step 4: Create a file 'log4j.properties' under src/main/resources.

log4j.properties

log4j.rootLogger=DEBUG,stdout

log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%p\t%d{ISO8601}\t%r\t%c\t[%t]\t%m%n

Step 5: Create a package 'com.sample.app' and define HelloWorld.java like below.

HelloWorld.java

package com.sample.app;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

public class HelloWorld {

 private static final Log log = LogFactory.getLog(HelloWorld.class);

 public static void main(String... args) {
  log.debug("Debug Message");
  log.info("Information Message");
  log.warn("Warning Message");
  log.error("Error Message");
  log.fatal("Fatal Message");
 }
}

When you ran HelloWorld.java application, you can able to see below messages in the console.

DEBUG 2018-05-22 12:20:30,397 0 com.sample.app.HelloWorld [main] Debug Message
INFO 2018-05-22 12:20:30,398 1 com.sample.app.HelloWorld [main] Information Message
WARN 2018-05-22 12:20:30,398 1 com.sample.app.HelloWorld [main] Warning Message
ERROR 2018-05-22 12:20:30,398 1 com.sample.app.HelloWorld [main] Error Message
FATAL 2018-05-22 12:20:30,398 1 com.sample.app.HelloWorld [main] Fatal Message

Project structure looks like below.

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