relation between log4j and apache.commons.logging

Question

Could anybody please tell me what's the relation between log4j and apache.commons.logging ? which one is more popular and better ?

I have imported an existing Application in which they have imported import org.apache.commons.logging.LogFactory; and written a separate class called Log and overridden some of the methods as critical, warn, info

For instance

 public static void info(String caller, String toWrite)
   {
      write(caller,toWrite,Log.INFO);
   }

Could anybody please tell me is log4j and apache.commons.logging are different ??

score 19 · Accepted Answer · answered Dec 13 '11 at 11:57

19

Apache Commons Logging is an abstraction for the concrete implementation. It uses log4j, if present and configured. I would use Commons logging in my code and log4j as logging implementation.

answered Dec 13 '11 at 11:57

Ulrich von Poblotzki

446
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I would use Commons logging in my code and log4j as logging implementation , then why to use Apache Commons Logging ?? – Pawan Dec 13 '11 at 12:08
You could use a different or no implementation at runtime, so your program is more flexible. – Ulrich von Poblotzki Dec 13 '11 at 13:07

score 8 · Answer 2 · answered Jul 10 '16 at 13:51

log4j is a logging framework, i.e. it provides the code to log messages. Commons-logging is an abstraction layer for logging frameworks, it doesn't log anything itself. For example if I write code using commons logging and deploy it on JBoss, the logging is done by log4j, but if I deploy it on WebSphere logging is done by WebSphere's own logging implementation. If I run the same code as a stand alone application it Java's own logging that is used

score 1 · Answer 3 · answered Oct 24 '17 at 15:36

As per java-doc documentation of commons-logging

Concrete subclass of LogFactory that implements the following algorithm to dynamically select a logging implementation class to instantiate a wrapper for:

Use a factory configuration attribute named org.apache.commons.logging.Log to identify the requested implementation class.
Use the org.apache.commons.logging.Log system property to identify the requested implementation class.
If Log4J is available, return an instance of org.apache.commons.logging.impl.Log4JLogger.
If JDK 1.4 or later is available, return an instance of org.apache.commons.logging.impl.Jdk14Logger.
Otherwise, return an instance of org.apache.commons.logging.impl.SimpleLog

Hence inference is:

commons-logging is more of abstraction. It can live without LOG4J also.
If Log4j exists, it chooses it. Otherwise other default available.
LOG4J is popular because of it's easy redirecting output to a file, and flexibility to configure log levels.

JavaDoc URL: https://commons.apache.org/proper/commons-logging/javadocs/api-1.1.3/index.html

relation between log4j and apache.commons.logging

3 Answers3