removing commons-logging and using slf4j causes errors in spring

Question

Specifically, I use spring only for configuring my project through ApplicationContext. In my spring xml I load some bean properties through PropertyPlaceholderConfigurer. Whenever in the dependencies I swap commons-logging-x.x with jcl-slf4j.jar the loading of the context fails with ClassNotFoundExceptions on the placeholder substitutions. Example:

In my spring.xml there is:

<bean id="testbean" class="${testbean.implementingClass}"/>

where testbean.implementingClass is defined in spring.properties:

testbean.implementingClass=my.implementation.TestClass

If I run the project using commons-logging jar all works perfectly. If I change it to jcl-slf4j then I get ClassNotFoundException that the class [${testbean.implementingClass}] was not found, i.e. it does not do the placeholder substituion. Has anyone observed this?

EDIT: My problem doesnt have to do with the jars because: From http://www.slf4j.org/legacy.html :

Our JCL over SLF4J implementation will allow you to migrate to SLF4J gradually, especially if some of the libraries your software depends on continue to use JCL for the foreseeable future. You can immediately enjoy the benefits of SLF4J's reliability and preserve backward compatibility at the same time. Just replace commons-logging.jar with jcl-over-slf4j.jar. Subsequently, the selection of the underlying logging framework will be done by SLF4J instead of JCL but without the class loader headaches plaguing JCL. The underlying logging framework can be any of the frameworks supported by SLF4J. Often times, replacing commons-logging.jar with jcl-over-slf4j.jar will immediately and permanently solve class loader issues related to commons logging.

Answer 1

When you use jcl-slf4j, you have to make sure you have excluded all commons-logging dependencies from your project. Make sure there is no commons-logging jar anywhere in the classpath.