Provide a way to specify the class loader to be used by a ClassPathXmlApplicationContextFactory [BATCH-2182]

[spring-projects-issues]

Mauro Molinari opened BATCH-2182 and commented

A ClassPathXmlApplicationContextFactory creates ClassPathXmlApplicationContext instances. The latter, by extending DefaultResourceLoader would allow to specify the class loader to use to locate resources. It would be very useful if the factory and the corresponding ClasspathXmlApplicationContextsFactoryBean (which, IMHO, should better be called ClassPathXmlApplicationContextFactoryFactoryBean, since it's a FactoryBean that creates factories and also would need an upper case "P" in "ClassPath") allowed to specify the class loader to use. This would allow to create an AutomaticJobRegistrar which registers jobs defined in child contexts loaded through a suitable class loader (which may in turn load classes at runtime from hot-deployed JARs, for instance).

Being able to specify just one class loader on the FactoryBean for all created factories would be better than nothing.

Right now I have to write my own FactoryBean and factory to achieve this, but I think that supporting this out-of-the-box should be quite simple and valuable.

By the way, I see that with 3.0.0.M2 ClassPathXmlApplicationContextFactory has been deprecated in favour of GenericApplicationContextFactory, which creates generic ConfigurableApplicationContexts. This enhancement might give a reason to revert the deprecation on ClassPathXmlApplicationContextFactory and add some additional value to it...

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Affects: 2.1.9

[spring-projects-issues]

Mauro Molinari commented

Also, to ease extension it would be useful if org.springframework.batch.core.configuration.support.ClasspathXmlApplicationContextsFactoryBean provided a hook to change the factory implementation, even if it were just an extension of org.springframework.batch.core.configuration.support.ClassPathXmlApplicationContextFactory. In fact, to work around my use case, the best would be to extend ClassPathXmlApplicationContextFactory and override its prepareContext(ConfigurableApplicationContext, ConfigurableApplicationContext) method to set the class loader before refreshing, but I can't change the fact that org.springframework.batch.core.configuration.support.ClasspathXmlApplicationContextsFactoryBean.getObject() goes straight with a new ClassPathXmlApplicationContextFactory(). So I have to apply some dirty workarounds to avoid to copy and paste a lot of code.

Last but not least, some getters on these configuration classes for private fields would also help extension :-)

[fmbenhassine]

ClassPathXmlApplicationContextFactory has been deprecated since v3 and will be removed in v5 (see #3836), so I see no value in putting efforts on it for the rest of its short life.