PathMatchingResourcePatternResolver provides duplicate resources with relative URL [SPR-14934]

[spring-projects-issues]

Stéphane Nicoll opened SPR-14934 and commented

This is a regression introduced by #18260

PathMatchingResourcePatternResolver#doFindAllClassPathResources first gets the path returned by the LaunchedUrlClassLoader which will add the URLs of all nested jar + the URL of BOOT-INF-classes, something like URL [jar:file:/Users/snicoll/workspace/pivotal/spring-framework-issues/SPR-13685/target/SPR-13685-0.0.1-SNAPSHOT.jar!/BOOT-INF/classes!/]

Because we need to get all XML files from the root (path is the empty string) we also invoke addAllClassLoaderJarRoots which works recursively as follow:

• does not add anything with LaunchedUrlClassLoader
• with classLoader.getSystemClassLoader() adds URL [jar:file:/Users/snicoll/workspace/pivotal/spring-framework-issues/SPR-13685/target/SPR-13685-0.0.1-SNAPSHOT.jar!/]
• with its parent (AppClassLoader) adds URL [jar:file:SPR-13685-0.0.1-SNAPSHOT.jar!/] via addClassPathManifestEntries. It also adds a bunch of entries from JDK jars
• does not add anything with ExtClassLoader

So we have the following entries for the candidate location:

jar:file:/Users/snicoll/workspace/pivotal/spring-framework-issues/SPR-13685/target/SPR-13685-0.0.1-SNAPSHOT.jar!/BOOT-INF/classes!/
jar:file:/Users/snicoll/workspace/pivotal/spring-framework-issues/SPR-13685/target/SPR-13685-0.0.1-SNAPSHOT.jar!/
jar:file:SPR-13685-0.0.1-SNAPSHOT.jar!/

So, for the same a.xml at the root of the classpath in src/main/resources we end up with the following candidates:

jar:file:/Users/snicoll/workspace/pivotal/spring-framework-issues/SPR-13685/target/SPR-13685-0.0.1-SNAPSHOT.jar!/BOOT-INF/classes!/a.xml
jar:file:/Users/snicoll/workspace/pivotal/spring-framework-issues/SPR-13685/target/SPR-13685-0.0.1-SNAPSHOT.jar!/BOOT-INF/classes/a.xml
jar:file:SPR-13685-0.0.1-SNAPSHOT.jar!/BOOT-INF/classes/a.xml

At this point I can only guess that each entry match each candidate in the list above (in that order). it isn't obvious how the second one lead to a lookup in BOOT-INF/classes though but given that a ! is missing in the second case, it's an indication it may come from that faulty URL.

A repro project is available

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Affects: 4.3 GA

Issue Links:

• #18260 PathMatchingResourcePatternResolver does not consider manifest based classpaths
• #19503 PathMatchingResourcePatternResolver finds duplicate resources for executable jars but not for executable wars

[spring-projects-issues]

Stéphane Nicoll commented

While working on this issue, we've discovered a Spring Boot issue as well, check #7449