[slf4j-user] Got a spring error when delegate log4j&Jul to slf4j then to log4j.

[Jason Wang]

Jason Wang wrote:
> Hi all,
>
> I am brand new to this wonderful slf4j tool(started to read about it 2 
> hours ago) and from my understanding switching to it should be a pain 
> free process.  However I ran into some problems.
>
> My project mainly uses log4j directly and it now depends on a 3rd 
> party library which uses JUL as  its logging framework. I would like 
> to make sure all the logs the 3rd party lib produces under the control 
> of my log4j settings. After a quick search on Google, the best 
> approach seems to be use the slf4j lib to bridge JUL to it and then 
> tell slf4j to use log4j as its backing implementation.
>
> So my solution idea is:
> 1.Delegating all of my log4j logging request to slf4j (by using log4j 
> over slf4j and removing the log4j jar)
> 2. Make sure  JUL log requests go to slf4j by using jul-to-slf4j.
>
> 3. Make sure slf4j uses log4j's implementation by using lf4j-log4j12. 
> So hopefully I get:
>   A: my log4j.xml settings still work.
>   B: the 3rd party lib's JUL logging requests end up going to log4j in 
> the end.
>
> My steps are:
>
> 1. comment out the dependency on log4j in my pom.xml, so the log4j.jar 
> will no longer be in my webapp/lib
>
> 2. introduce the following 3 dependencies.
> <dependency>
>         <groupId>org.slf4j</groupId>
>         <artifactId>log4j-over-slf4j</artifactId>
>         <version>1.5.8</version>
>       </dependency>
>           <dependency>
>           <groupId>org.slf4j</groupId>
>           <artifactId>slf4j-log4j12</artifactId>
>           <version>1.5.8</version>
>           <scope>test</scope>
>       </dependency>
>         <dependency>
>           <groupId>org.slf4j</groupId>
>           <artifactId>jul-to-slf4j</artifactId>
>           <version>1.5.8</version>
>       </dependency>
>
> After applying the changes, the project still builds, great. But it 
> fails immediately on runtime:
>
> Spring complains that it could not initialize org.apache.log4j.logger. 
> Detailed message:
>
> Nested in org.springframework.beans.factory.BeanCreationException: 
> Error creating bean with name 'paypalRestService' defined in file 
> [/home/jasonw/dev/bulletin-paymentengine/target/classes/com/bulletin/paymentengine/api/paypal/rest/resource/PaypalRestService.class]: 
> Instantiation of bean failed; nested exception is 
> java.lang.NoClassDefFoundError: Could not initialize class 
> org.apache.log4j.Logger:
> java.lang.NoClassDefFoundError: Could not initialize class 
> org.apache.log4j.Logger
>   at 
> com.bulletin.paymentengine.api.paypal.rest.resource.PaypalRestService.<clinit>(PaypalRestService.java:45) 
>
>
>
> So, my questions are: will my solution work at all in theory? Is there 
> anything wrong in my solution?
> How to fix this spring problem?
>
>
> Thanks alot.
>
> Jas
>
>
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Just realized that log4j-over-slf4j.jar can not live together with 
slf4j-logj12.jar. .. So my approach will never work.

So folks, what will be the best approach to my question(delegate JUL to 
log4j)?

I guess on way to do it is to change my code from log4j to slf4j-api so 
I can still use jul-to-slf4j and slf4j-to-log4j. But that will not be 
pain free at all, will it?

Thanks

Jason