Currently, we do not officially support OC4J. Some users have managed to get it running, while others have experienced errors such as the following:

2005-03-21 12:55:26,095 WARN [sf.ehcache.hibernate.Plugin] Could not find configuration for com.atlassian.confluence.security.SpacePermission.
 Configuring using the defaultCache settings.
2005-03-21 12:55:30,733 WARN [sf.hibernate.xml.XMLDatabinder] Problem opening output stylesheet - databinding disabled
java.lang.ClassCastException
        at javax.xml.transform.TransformerFactory.newInstance(TransformerFactory.java:119)
        at net.sf.hibernate.xml.XMLDatabinder.getOutputStyleSheetTemplates(XMLDatabinder.java:254)
        at net.sf.hibernate.impl.SessionFactoryImpl.<init>(SessionFactoryImpl.java:160)
        at net.sf.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:791)
        at org.springframework.orm.hibernate.LocalSessionFactoryBean.newSessionFactory(LocalSessionFactoryBean.java:467)
        at org.springframework.orm.hibernate.LocalSessionFactoryBean.afterPropertiesSet(LocalSessionFactoryBean.java:405)
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.j
ava:1057)
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:287
)
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:205
)
        at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:204)
        at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:136)
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.resolveReference(AbstractAutowireCapableBeanFactory.ja
va:954)
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.resolveValueIfNecessary(AbstractAutowireCapableBeanFac
tory.java:889)
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyPropertyValues(AbstractAutowireCapableBeanFactory
.java:827)
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:6
62)
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:270
)
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:205
)
        at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:204)
        at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:136)
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.resolveReference(AbstractAutowireCapableBeanFactory.ja
va:954)
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.resolveValueIfNecessary(AbstractAutowireCapableBeanFac
tory.java:889)
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyPropertyValues(AbstractAutowireCapableBeanFactory
.java:827)
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:6
62)
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:270
)
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:205
)
        at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:204)
        at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:136)
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.resolveReference(AbstractAutowireCapableBeanFactory.ja
va:954)
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.resolveValueIfNecessary(AbstractAutowireCapableBeanFac
tory.java:889)
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyPropertyValues(AbstractAutowireCapableBeanFactory
.java:827)
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:6
62)
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:270
)
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:205
)
        at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:204)
        at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:136)
        at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBeansOfType(DefaultListableBeanFactory.java:140)
        at org.springframework.context.support.AbstractApplicationContext.getBeansOfType(AbstractApplicationContext.java:474)
        at org.springframework.context.support.AbstractApplicationContext.refreshListeners(AbstractApplicationContext.java:392)
        at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:281)
        at org.springframework.web.context.support.XmlWebApplicationContext.refresh(XmlWebApplicationContext.java:131)
        at org.springframework.web.context.ContextLoader.createWebApplicationContext(ContextLoader.java:156)
        at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:97)
        at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:48)
        at bucket.container.ContainerContextLoaderListener.contextInitialized(ContainerContextLoaderListener.java:33)
        at com.evermind.server.http.HttpApplication.initDynamic(HttpApplication.java:814)
        at com.evermind.server.http.HttpApplication.<init>(HttpApplication.java:542)
        at com.evermind.server.Application.getHttpApplication(Application.java:889)
        at com.evermind.server.http.HttpServer.getHttpApplication(HttpServer.java:690)
        at com.evermind.server.http.HttpSite.getApplication(HttpSite.java:420)
        at com.evermind.server.http.HttpRequestHandler.processRequest(HttpRequestHandler.java:422)
        at com.evermind.server.http.HttpRequestHandler.run(HttpRequestHandler.java:270)
        at com.evermind.server.http.HttpRequestHandler.run(HttpRequestHandler.java:112)
        at com.evermind.util.ReleasableResourcePooledExecutor$MyWorker.run(ReleasableResourcePooledExecutor.java:186)
        at java.lang.Thread.run(Thread.java:534)
2005-03-21 12:55:30,834 WARN [sf.ehcache.hibernate.Plugin] Could not find configuration for net.sf.hibernate.cache.UpdateTimestampsCache. Conf
iguring using the defaultCache settings.

It would be nice to be able to come up with a known-good OC4J configuration, and support it out of the box.