Using 'ImportAutoConfigurationImportSelector' in the jar package loaded by the custom class loader will raise `ClassNotFoundException`.

I try to use ‘UrlClassLoader’ to load a jar package. In this jar package, an ‘AnnotationConfigApplicationContext’ will be started, and the ‘@ImportAutoConfiguration’ annotation will be used. At this time, my application will throw an ‘IllegalargumentException’ caused by ‘ClassNotFoundException’.

I have a simple example. (https://github.com/aoyvx/CustomClassLoaderExample). The following stack will be thrown when the module’app-one 'is run.

Exception in thread "main" java.lang.IllegalArgumentException: Could not find class [org.example.impl.SimpleConfig]
	at org.springframework.util.ClassUtils.resolveClassName(ClassUtils.java:334)
	at org.springframework.boot.autoconfigure.ImportAutoConfigurationImportSelector.getAnnotations(ImportAutoConfigurationImportSelector.java:132)
	at org.springframework.boot.autoconfigure.ImportAutoConfigurationImportSelector.getCandidateConfigurations(ImportAutoConfigurationImportSelector.java:77)
	at org.springframework.boot.autoconfigure.AutoConfigurationImportSelector.getAutoConfigurationEntry(AutoConfigurationImportSelector.java:125)
	at org.springframework.boot.autoconfigure.AutoConfigurationImportSelector$AutoConfigurationGroup.process(AutoConfigurationImportSelector.java:440)
	at org.springframework.context.annotation.ConfigurationClassParser$DeferredImportSelectorGrouping.getImports(ConfigurationClassParser.java:879)
	at org.springframework.context.annotation.ConfigurationClassParser$DeferredImportSelectorGroupingHandler.processGroupImports(ConfigurationClassParser.java:809)
	at org.springframework.context.annotation.ConfigurationClassParser$DeferredImportSelectorHandler.process(ConfigurationClassParser.java:780)
	at org.springframework.context.annotation.ConfigurationClassParser.parse(ConfigurationClassParser.java:193)
	at org.springframework.context.annotation.ConfigurationClassPostProcessor.processConfigBeanDefinitions(ConfigurationClassPostProcessor.java:331)
	at org.springframework.context.annotation.ConfigurationClassPostProcessor.postProcessBeanDefinitionRegistry(ConfigurationClassPostProcessor.java:247)
	at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanDefinitionRegistryPostProcessors(PostProcessorRegistrationDelegate.java:311)
	at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(PostProcessorRegistrationDelegate.java:112)
	at org.springframework.context.support.AbstractApplicationContext.invokeBeanFactoryPostProcessors(AbstractApplicationContext.java:746)
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:564)
	at org.example.impl.EchoApp.init(EchoApp.java:15)
	at com.example.app.App.main(App.java:15)
Caused by: java.lang.ClassNotFoundException: org.example.impl.SimpleConfig
	at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:641)
	at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:188)
	at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:520)
	at java.base/java.lang.Class.forName0(Native Method)
	at java.base/java.lang.Class.forName(Class.java:467)
	at org.springframework.util.ClassUtils.forName(ClassUtils.java:284)
	at org.springframework.util.ClassUtils.resolveClassName(ClassUtils.java:324)
	... 16 more
Disconnected from the target VM, address: '127.0.0.1:54192', transport: 'socket'

Process finished with exit code 1

I modified ImportAutoConfigurationImportSelector#getExclusions and ImportAutoConfigurationImportSelector#getAnnotations in module app-b, replace null with getBeanClassLoader(). at this time, the program can run normally.

[wilkinsona]

I seem to remember we’ve had a few issues in this area in the past but I can’t find them in the issue tracker

I have a recollection of doing a sweep of the codebase trying to consistently use the bean class loader or the class loader from the resource loader or something like that. I can’t find the issue either though 🤷.

It feels like using the bean classloader is the right thing to do with those calls

+1, particularly as we already use the bean class loader to load the factory names. We should consistently use the same class loader.

I hope I can submit this PR

Yes please, @aoyvx. A PR would be most welcome.

[snicoll]

Closing in favor of PR #31798