Component scan fails to find bean candidates in the embedded jar file in META-INF/context.xml for embedded Tomcat application

[osnsergey]

Description
Component Scan can't find annotated beans in the Web application if beans are located in the embedded .jar file.

Reproducer
A small sample application for the issue has been created: GitHub Repository (Java 17, Gradle).

Exception Stack Trace:

21:42:59.048 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory -- Creating shared instance of singleton bean 'localizationController'
21:42:59.070 [main] WARN org.springframework.web.context.support.XmlWebApplicationContext -- Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'localizationController': Unsatisfied dependency expressed through field 'langPackageLoader': No qualifying bean of type 'com.my.app.localization.LangPackageLoader' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
21:42:59.076 [main] ERROR org.springframework.web.context.ContextLoader -- Context initialization failed
org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'localizationController': Unsatisfied dependency expressed through field 'langPackageLoader': No qualifying bean of type 'com.my.app.localization.LangPackageLoader' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
        at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.resolveFieldValue(AutowiredAnnotationBeanPostProcessor.java:788)
        at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:768)
        at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:146)
        at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessProperties(AutowiredAnnotationBeanPostProcessor.java:509)
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1445)
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:600)
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:523)
        at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:339)
        at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:346)
        at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:337)
        at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202)
        at org.springframework.beans.factory.support.DefaultListableBeanFactory.instantiateSingleton(DefaultListableBeanFactory.java:1155)
        at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingleton(DefaultListableBeanFactory.java:1121)
        at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:1056)
        at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:987)
        at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:627)
        at org.springframework.web.context.ContextLoader.configureAndRefreshWebApplicationContext(ContextLoader.java:394)
        at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:274)
        at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:126)
        at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4008)
        at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:4436)
        at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:164)
        at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1203)
        at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1193)
        at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
        at org.apache.tomcat.util.threads.InlineExecutorService.execute(InlineExecutorService.java:75)
        at java.base/java.util.concurrent.AbstractExecutorService.submit(AbstractExecutorService.java:145)
        at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:749)
        at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:772)
        at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:164)
        at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1203)
        at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1193)
        at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
        at org.apache.tomcat.util.threads.InlineExecutorService.execute(InlineExecutorService.java:75)
        at java.base/java.util.concurrent.AbstractExecutorService.submit(AbstractExecutorService.java:145)
        at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:749)
        at org.apache.catalina.core.StandardEngine.startInternal(StandardEngine.java:203)
        at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:164)
        at org.apache.catalina.core.StandardService.startInternal(StandardService.java:415)
        at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:164)
        at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:870)
        at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:164)
        at org.apache.catalina.startup.Tomcat.start(Tomcat.java:437)
        at com.test.app.runner.AppRunner.run(AppRunner.java:42)
        at com.test.app.runner.AppRunner.main(AppRunner.java:131)
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)
        at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.base/java.lang.reflect.Method.invoke(Method.java:568)
        at org.springframework.boot.loader.MainMethodRunner.run(MainMethodRunner.java:49)
        at org.springframework.boot.loader.Launcher.launch(Launcher.java:95)
        at org.springframework.boot.loader.Launcher.launch(Launcher.java:58)
        at com.test.app.runner.JarLauncher.main(JarLauncher.java:38)
Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'com.my.app.localization.LangPackageLoader' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}

        at org.springframework.beans.factory.support.DefaultListableBeanFactory.raiseNoMatchingBeanFound(DefaultListableBeanFactory.java:2177)
        at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1627)
        at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1552)
        at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.resolveFieldValue(AutowiredAnnotationBeanPostProcessor.java:785)
        ... 52 common frames omitted

How to reproduce
Clone https://github.com/osnsergey/Spring62TestWebApp2, use README.md commands to run the sample.

Bean definitions can't be found in the following jar:

spring62webapp.jar!\WEB-INF\lib\localization.jar!\

[jhoeller]

@osnsergey any insight into where PathMatchingResourcePatternResolver goes wrong in this follow-up? I'll look at it in depth tomorrow morning, with the aim to resolve it for the 6.2.4 release which we intend to publish in about 24 hours.

[osnsergey]

@jhoeller , no, I didn't analyze it deeply yet...

[osnsergey]

In Spring 6.1

Stack

"main@1" prio=5 tid=0x1 nid=NA runnable
  java.lang.Thread.State: RUNNABLE
	  at org.springframework.core.io.support.PathMatchingResourcePatternResolver.doFindPathMatchingJarResources(PathMatchingResourcePatternResolver.java:744)
	  at org.springframework.core.io.support.PathMatchingResourcePatternResolver.findPathMatchingResources(PathMatchingResourcePatternResolver.java:601)
	  at org.springframework.core.io.support.PathMatchingResourcePatternResolver.getResources(PathMatchingResourcePatternResolver.java:335)
	  at org.springframework.context.support.AbstractApplicationContext.getResources(AbstractApplicationContext.java:1520)
	  at org.springframework.context.annotation.ClassPathScanningCandidateComponentProvider.scanCandidateComponents(ClassPathScanningCandidateComponentProvider.java:457)
 ...

protected Set<Resource> doFindPathMatchingJarResources(Resource rootDirResource, URL rootDirUrl, String subPattern)
			throws IOException {
...
ln745.                  Set<Resource> result = new LinkedHashSet<>(64);
ln746.			for (Enumeration<JarEntry> entries = jarFile.entries(); entries.hasMoreElements();) {
				JarEntry entry = entries.nextElement();
				String entryPath = entry.getName();
				if (entryPath.startsWith(rootEntryPath)) {
					String relativePath = entryPath.substring(rootEntryPath.length());
					if (getPathMatcher().match(subPattern, relativePath)) {
ln751.					        result.add(rootDirResource.createRelative(relativePath));
					}
				}
			}
...
}

on ln746: jarFile = C:\Work\Spring62TestWebApp2\spring62webapp\result\release\spring62webapp.jar!/WEB-INF/lib/localization.jar

rootDirResource = URL [jar:file:/C:/Work/Spring62TestWebApp2/spring62webapp/result/release/spring62webapp.jar!/WEB-INF/lib/localization.jar!/com/my/app/localization/]

rootDirUrl = jar:file:/C:/Work/Spring62TestWebApp2/spring62webapp/result/release/spring62webapp.jar!/WEB-INF/lib/localization.jar!/com/my/app/localization/

subPattern = **/*.class

on ln751 result is filled with all classes from the localization.jar:

result = {LinkedHashSet@3528}  size = 3
 0 = {UrlResource@3927} "URL [jar:file:/C:/Work/Spring62TestWebApp2/spring62webapp/result/release/spring62webapp.jar!/WEB-INF/lib/localization.jar!/com/my/app/localization/LangPackage.class]"
 1 = {UrlResource@3928} "URL [jar:file:/C:/Work/Spring62TestWebApp2/spring62webapp/result/release/spring62webapp.jar!/WEB-INF/lib/localization.jar!/com/my/app/localization/LangPackageLoader.class]"
 2 = {UrlResource@3929} "URL [jar:file:/C:/Work/Spring62TestWebApp2/spring62webapp/result/release/spring62webapp.jar!/WEB-INF/lib/localization.jar!/com/my/app/localization/LangPackageLoaderImpl.class]"

Eventually in the

	private Set<BeanDefinition> scanCandidateComponents(String basePackage) {
		Set<BeanDefinition> candidates = new LinkedHashSet<>();
		try {
			String packageSearchPath = ResourcePatternResolver.CLASSPATH_ALL_URL_PREFIX +
					resolveBasePackage(basePackage) + '/' + this.resourcePattern;
ln457.		        Resource[] resources = getResourcePatternResolver().getResources(packageSearchPath);

On ln457 the result from the doFindPathMatchingJarResources is then processed for bean candidates.

---

In Spring 6.2

Stack

"main@1" prio=5 tid=0x1 nid=NA runnable
  java.lang.Thread.State: RUNNABLE
	  at org.springframework.core.io.support.PathMatchingResourcePatternResolver.doFindPathMatchingJarResources(PathMatchingResourcePatternResolver.java:803)
	  at org.springframework.core.io.support.PathMatchingResourcePatternResolver.findPathMatchingResources(PathMatchingResourcePatternResolver.java:713)
	  at org.springframework.core.io.support.PathMatchingResourcePatternResolver.getResources(PathMatchingResourcePatternResolver.java:351)
	  at org.springframework.context.support.AbstractApplicationContext.getResources(AbstractApplicationContext.java:1549)
	  at org.springframework.context.annotation.ClassPathScanningCandidateComponentProvider.scanCandidateComponents(ClassPathScanningCandidateComponentProvider.java:457)

	protected Set<Resource> doFindPathMatchingJarResources(Resource rootDirResource, URL rootDirUrl, String subPattern)
			throws IOException {
...
		if (separatorIndex >= 0) {
ln811.		        jarFileUrl = urlFile.substring(0, separatorIndex);
			rootEntryPath = urlFile.substring(separatorIndex + 2);  // both separators are 2 chars
			NavigableSet<String> entriesCache = this.jarEntriesCache.get(jarFileUrl);
			if (entriesCache != null) {
				Set<Resource> result = new LinkedHashSet<>(64);
				// Clean root entry path to match jar entries format without "!" separators
ln817.			        rootEntryPath = rootEntryPath.replace(ResourceUtils.JAR_URL_SEPARATOR, "/");
				// Search sorted entries from first entry with rootEntryPath prefix
ln820.			        for (String entryPath : entriesCache.tailSet(rootEntryPath, false)) {
					if (!entryPath.startsWith(rootEntryPath)) {
						// We are beyond the potential matches in the current TreeSet.
ln822.				        	break;
					}
					String relativePath = entryPath.substring(rootEntryPath.length());
					if (getPathMatcher().match(subPattern, relativePath)) {
						result.add(rootDirResource.createRelative(relativePath));
					}
				}
ln829.			        return result;

...

}

rootDirResource = URL [jar:file:/C:/Work/Spring62TestWebApp2/spring62webapp/result/release/spring62webapp.jar!/WEB-INF/lib/localization.jar!/com/my/app/localization/]

rootDirUrl = jar:file:/C:/Work/Spring62TestWebApp2/spring62webapp/result/release/spring62webapp.jar!/WEB-INF/lib/localization.jar!/com/my/app/localization/

subPattern = **/*.class

on ln811: jarFileUrl = file:/C:/Work/Spring62TestWebApp2/spring62webapp/result/release/spring62webapp.jar

on ln817: rootEntryPath = WEB-INF/lib/localization.jar/com/my/app/localization/

on ln820: entryPath = WEB-INF/lib/log4j-over-slf4j-2.0.12.jar

on ln822 the loop breaks and result isn't filled at all.

Maybe the unconditional return on ln829 is a defect because the code below looks like in Spring 6.1 and could work... But that's just a guess...