Re: [equinox-dev] Using Log4J in Equinox framework

[Martin Below <martin@xxxxxxxxxxxxxxxxxxx>]

> I think the simplest way you want is to change a log4j Jar file to a 
> log4j bundle. Just create a new bundle project, put log4j.jar in the 
> bundle directory, add log4j.jar to the project build path, export all 
> the packages in log4j.jar,(through Export-Package in bundle's 
> MANIFEST.MF), add log4j to the bundle class path (through 
> Bundle-Classpath in bundle's MANIFEST.MF). And then you get a log4j 
> bundle which can run on Equinox.
You may also use a prebuild bundle from springsource's 
bundle-repository: 
http://www.springsource.com/repository/app/search?query=log4j
>  
> You want to use log4j APIs, just import log4j package in other bundle 
> (through Import-Package in bundle's MANIFEST.MF) and use it directly. 
> But in this way, loading of the configuration file log4j.properties is 
> a problem. log4j.properties can locate in the jar bundle or use a 
> argument to figure it out.
To work around this, create a new fragment bundle (ex. 
foo.bar.logging.config), which only contains your log4j.properties file. 
You need to add the following line to the bundle's manifest:
Fragment-Host: com.springsource.org.apache.log4j.

This makes sure that the log4j.properties file is visible from within 
the log4j bundle's classloader without "patching" the log4j-bundle's 
manifest.
In contrast to the equinox buddy-classloading, this is part of the OSGi 
standard, and therefore will also work in other OSGi frameworks.

Cheers,
Martin Below