Make jar caching configurable through setUseCaches

Closes gh-34678

Author: jhoeller

spring-core/src/main/java/org/springframework/core/io/support/PathMatchingResourcePatternResolver.java

@@ -215,6 +215,8 @@
  */
 public class PathMatchingResourcePatternResolver implements ResourcePatternResolver {
 
+	private static final Resource[] EMPTY_RESOURCE_ARRAY = {};
+
 	private static final Log logger = LogFactory.getLog(PathMatchingResourcePatternResolver.class);
 
 	/**
@@ -257,6 +259,8 @@ public class PathMatchingResourcePatternResolver implements ResourcePatternResol
 
 	private PathMatcher pathMatcher = new AntPathMatcher();
 
+	private boolean useCaches = true;
+
 	private final Map<String, Resource[]> rootDirCache = new ConcurrentHashMap<>();
 
 	private final Map<String, NavigableSet<String>> jarEntriesCache = new ConcurrentHashMap<>();
@@ -331,6 +335,22 @@ public PathMatcher getPathMatcher() {
 		return this.pathMatcher;
 	}
 
+	/**
+	 * Specify whether this resolver should use jar caches. Default is {@code true}.
+	 * <p>Switch this flag to {@code false} in order to avoid any jar caching, at
+	 * the {@link JarURLConnection} level as well as within this resolver instance.
+	 * <p>Note that {@link JarURLConnection#setDefaultUseCaches} can be turned off
+	 * independently. This resolver-level setting is designed to only enforce
+	 * {@code JarURLConnection#setUseCaches(false)} if necessary but otherwise
+	 * leaves the JVM-level default in place.
+	 * @since 6.1.19
+	 * @see JarURLConnection#setUseCaches
+	 * @see #clearCache()
+	 */
+	public void setUseCaches(boolean useCaches) {
+		this.useCaches = useCaches;
+	}
+
 
 	@Override
 	public Resource getResource(String location) {
@@ -354,7 +374,7 @@ public Resource[] getResources(String locationPattern) throws IOException {
 				// all class path resources with the given name
 				Collections.addAll(resources, findAllClassPathResources(locationPatternWithoutPrefix));
 			}
-			return resources.toArray(new Resource[0]);
+			return resources.toArray(EMPTY_RESOURCE_ARRAY);
 		}
 		else {
 			// Generally only look for a pattern after a prefix here,
@@ -398,7 +418,7 @@ protected Resource[] findAllClassPathResources(String location) throws IOExcepti
 		if (logger.isTraceEnabled()) {
 			logger.trace("Resolved class path location [" + path + "] to resources " + result);
 		}
-		return result.toArray(new Resource[0]);
+		return result.toArray(EMPTY_RESOURCE_ARRAY);
 	}
 
 	/**
@@ -535,7 +555,9 @@ protected void addClassPathManifestEntries(Set<Resource> result) {
 		Set<ClassPathManifestEntry> entries = this.manifestEntriesCache;
 		if (entries == null) {
 			entries = getClassPathManifestEntries();
-			this.manifestEntriesCache = entries;
+			if (this.useCaches) {
+				this.manifestEntriesCache = entries;
+			}
 		}
 		for (ClassPathManifestEntry entry : entries) {
 			if (!result.contains(entry.resource()) &&
@@ -687,7 +709,9 @@ else if (commonPrefix.equals(rootDirPath)) {
 			if (rootDirResources == null) {
 				// Lookup for specific directory, creating a cache entry for it.
 				rootDirResources = getResources(rootDirPath);
-				this.rootDirCache.put(rootDirPath, rootDirResources);
+				if (this.useCaches) {
+					this.rootDirCache.put(rootDirPath, rootDirResources);
+				}
 			}
 		}
 
@@ -719,7 +743,7 @@ else if (ResourceUtils.isJarURL(rootDirUrl) || isJarResource(rootDirResource)) {
 		if (logger.isTraceEnabled()) {
 			logger.trace("Resolved location pattern [" + locationPattern + "] to resources " + result);
 		}
-		return result.toArray(new Resource[0]);
+		return result.toArray(EMPTY_RESOURCE_ARRAY);
 	}
 
 	/**
@@ -840,6 +864,9 @@ protected Set<Resource> doFindPathMatchingJarResources(Resource rootDirResource,
 
 		if (con instanceof JarURLConnection jarCon) {
 			// Should usually be the case for traditional JAR files.
+			if (!this.useCaches) {
+				jarCon.setUseCaches(false);
+			}
 			try {
 				jarFile = jarCon.getJarFile();
 				jarFileUrl = jarCon.getJarFileURL().toExternalForm();
@@ -903,8 +930,10 @@ protected Set<Resource> doFindPathMatchingJarResources(Resource rootDirResource,
 					}
 				}
 			}
-			// Cache jar entries in TreeSet for efficient searching on re-encounter.
-			this.jarEntriesCache.put(jarFileUrl, entriesCache);
+			if (this.useCaches) {
+				// Cache jar entries in TreeSet for efficient searching on re-encounter.
+				this.jarEntriesCache.put(jarFileUrl, entriesCache);
+			}
 			return result;
 		}
 		finally {

spring-core/src/test/java/org/springframework/core/io/support/PathMatchingResourcePatternResolverTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2024 the original author or authors.
+ * Copyright 2002-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -132,6 +132,7 @@ void encodedHashtagInPath() throws IOException {
 			Path rootDir = Paths.get("src/test/resources/custom%23root").toAbsolutePath();
 			URL root = new URL("file:" + rootDir + "/");
 			resolver = new PathMatchingResourcePatternResolver(new DefaultResourceLoader(new URLClassLoader(new URL[] {root})));
+			resolver.setUseCaches(false);
 			assertExactFilenames("classpath*:scanned/*.txt", "resource#test1.txt", "resource#test2.txt");
 		}