How to find which library slf4j has bound itself to?

Question

I am using slf4j for logging in my application. I get the purpose of slf4j. I would like to know how to find out which logging-library slf4j is currently binding to. I have log4j in my referenced libraries. I am assuming that slf4j has bound itself to log4j.

What I would like to know is, is there any way to explicitly confirm this binding?

I swear there was a way to turn on slf4j debugging (meta debugging) but I can't remember what it was. None of the answers address that. — Sridhar Sarnobat, Jan 15 '19 at 23:25

score 72 · Accepted Answer · answered May 08 '12 at 19:58

72

Just do what SLF4J does to discover the binding:

final StaticLoggerBinder binder = StaticLoggerBinder.getSingleton();

Now you can try to find out what is the actual implementation logback in my case:

System.out.println(binder.getLoggerFactory());
System.out.println(binder.getLoggerFactoryClassStr());

This prints:

ch.qos.logback.classic.LoggerContext[default]
ch.qos.logback.classic.selector.DefaultContextSelector

answered May 08 '12 at 19:58

Tomasz Nurkiewicz

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How can I find which jar file the logger (logback in the above example) came from? – Jason May 18 '15 at 04:02
@Jason how about asking the class loader? – Kedar Mhaswade Apr 05 '17 at 17:12
1

How do I ask the class loader? – Jason Jun 14 '17 at 14:23
3

`StaticLoggerBinder` is not part of `slf4j-api`, so this method does not work. – wheeler Jan 03 '18 at 20:02

score 8 · Answer 2 · answered May 08 '12 at 19:58

8

The StaticLoggerBinder's getLoggerFactoryClassStr() method is probably what you're looking for.

answered May 08 '12 at 19:58

leedm777

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score 4 · Answer 3 · answered Jul 20 '16 at 16:00

4

Easy. Put a breakpoint on .. say.. LOG.info(...). Once debugger stops there, step into.. and viola.. you will find yourself in the code of the actual logger... say log4j or logback.. whatever.

answered Jul 20 '16 at 16:00

Apurva Singh

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score 3 · Answer 4 · answered May 14 '19 at 16:51

It's possible to do this using the main slf4j public API (i.e. without the internal StaticLoggerBinder), e.g. to detect if slf4j has bpound to log4j2:

if ("org.apache.logging.slf4j.Log4jLoggerFactory".equals(
    org.slf4j.LoggerFactory.getILoggerFactory().getClass().getName()
) 
{ ... }

score 1 · Answer 5 · answered Aug 04 '22 at 10:01

1

Or, avoiding the need to have StaticLoggerBinder (which is not part of slf4j-api):

log.info(log.getClass().getName());

In my case this prints

ch.qos.logback.classic.Logger

answered Aug 04 '22 at 10:01

Tumelo Galenos

167
8

How to find which library slf4j has bound itself to?

5 Answers5

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