Do not close GraalVM Native image FileSystem after classpath scanning

As can be seen in a modified version of the following example project,
attempting to access a resource discovered via classpath scanning
within a GraalVM native image -- for example via the Files.exists(...)
invocation in FileSystemResource -- currently results in a
ClosedFileSystemException since PathMatchingResourcePatternResolver
explicitly closes the native image FileSystem that backs `resource:`
resources.

Sample project: https://github.com/joshlong/spring-boot-3-aot-graphql

To address this issue, this commit removes the explicit close()
invocation for custom FileSystems after classpath scanning in
PathMatchingResourcePatternResolver.

See spring-projects/spring-graphql#495
Closes gh-29397

Author: sbrannen

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

@@ -31,7 +31,6 @@
 import java.net.URL;
 import java.net.URLClassLoader;
 import java.net.URLConnection;
-import java.nio.file.FileSystem;
 import java.nio.file.FileSystemNotFoundException;
 import java.nio.file.FileSystems;
 import java.nio.file.Files;
@@ -748,76 +747,68 @@ protected Set<Resource> doFindPathMatchingFileResources(Resource rootDirResource
 			return Collections.emptySet();
 		}
 
-		FileSystem fileSystem = null;
-		try {
-			Path rootPath = null;
-			if (rootDirUri.isAbsolute() && !rootDirUri.isOpaque()) {
-				// Prefer Path resolution from URI if possible
+		Path rootPath = null;
+		if (rootDirUri.isAbsolute() && !rootDirUri.isOpaque()) {
+			// Prefer Path resolution from URI if possible
+			try {
 				try {
-					try {
-						rootPath = Path.of(rootDirUri);
-					}
-					catch (FileSystemNotFoundException ex) {
-						// If the file system was not found, assume it's a custom file system that needs to be installed.
-						fileSystem = FileSystems.newFileSystem(rootDirUri, Map.of(), ClassUtils.getDefaultClassLoader());
-						rootPath = Path.of(rootDirUri);
-					}
+					rootPath = Path.of(rootDirUri);
 				}
-				catch (Exception ex) {
-					if (logger.isDebugEnabled()) {
-						logger.debug("Failed to resolve %s in file system: %s".formatted(rootDirUri, ex));
-					}
-					// Fallback via Resource.getFile() below
+				catch (FileSystemNotFoundException ex) {
+					// If the file system was not found, assume it's a custom file system that needs to be installed.
+					FileSystems.newFileSystem(rootDirUri, Map.of(), ClassUtils.getDefaultClassLoader());
+					rootPath = Path.of(rootDirUri);
 				}
 			}
-			if (rootPath == null) {
-				// Resource.getFile() resolution as a fallback -
-				// for custom URI formats and custom Resource implementations
-				rootPath = Path.of(rootDirResource.getFile().getAbsolutePath());
+			catch (Exception ex) {
+				if (logger.isDebugEnabled()) {
+					logger.debug("Failed to resolve %s in file system: %s".formatted(rootDirUri, ex));
+				}
+				// Fallback via Resource.getFile() below
 			}
+		}
+		if (rootPath == null) {
+			// Resource.getFile() resolution as a fallback -
+			// for custom URI formats and custom Resource implementations
+			rootPath = Path.of(rootDirResource.getFile().getAbsolutePath());
+		}
 
-			String rootDir = StringUtils.cleanPath(rootPath.toString());
-			if (!rootDir.endsWith("/")) {
-				rootDir += "/";
-			}
+		String rootDir = StringUtils.cleanPath(rootPath.toString());
+		if (!rootDir.endsWith("/")) {
+			rootDir += "/";
+		}
 
-			Path rootPathForPattern = rootPath;
-			String resourcePattern = rootDir + StringUtils.cleanPath(subPattern);
-			Predicate<Path> isMatchingFile = path -> (!path.equals(rootPathForPattern) &&
-					getPathMatcher().match(resourcePattern, StringUtils.cleanPath(path.toString())));
+		Path rootPathForPattern = rootPath;
+		String resourcePattern = rootDir + StringUtils.cleanPath(subPattern);
+		Predicate<Path> isMatchingFile = path -> (!path.equals(rootPathForPattern) &&
+				getPathMatcher().match(resourcePattern, StringUtils.cleanPath(path.toString())));
 
-			if (logger.isTraceEnabled()) {
-				logger.trace("Searching directory [%s] for files matching pattern [%s]"
-						.formatted(rootPath.toAbsolutePath(), subPattern));
-			}
+		if (logger.isTraceEnabled()) {
+			logger.trace("Searching directory [%s] for files matching pattern [%s]"
+					.formatted(rootPath.toAbsolutePath(), subPattern));
+		}
 
-			Set<Resource> result = new LinkedHashSet<>();
-			try (Stream<Path> files = Files.walk(rootPath)) {
-				files.filter(isMatchingFile).sorted().forEach(file -> {
-					try {
-						result.add(new FileSystemResource(file));
-					}
-					catch (Exception ex) {
-						if (logger.isDebugEnabled()) {
-							logger.debug("Failed to convert file %s to an org.springframework.core.io.Resource: %s"
-									.formatted(file, ex));
-						}
+		Set<Resource> result = new LinkedHashSet<>();
+		try (Stream<Path> files = Files.walk(rootPath)) {
+			files.filter(isMatchingFile).sorted().forEach(file -> {
+				try {
+					result.add(new FileSystemResource(file));
+				}
+				catch (Exception ex) {
+					if (logger.isDebugEnabled()) {
+						logger.debug("Failed to convert file %s to an org.springframework.core.io.Resource: %s"
+								.formatted(file, ex));
 					}
-				});
-			}
-			catch (Exception ex) {
-				if (logger.isDebugEnabled()) {
-					logger.debug("Failed to complete search in directory [%s] for files matching pattern [%s]: %s"
-							.formatted(rootPath.toAbsolutePath(), subPattern, ex));
 				}
-			}
-			return result;
+			});
 		}
-		finally {
-			if (fileSystem != null) {
-				fileSystem.close();
+		catch (Exception ex) {
+			if (logger.isDebugEnabled()) {
+				logger.debug("Failed to complete search in directory [%s] for files matching pattern [%s]: %s"
+						.formatted(rootPath.toAbsolutePath(), subPattern, ex));
 			}
 		}
+		return result;
 	}
 
 	/**

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

@@ -19,6 +19,7 @@
 import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.io.UncheckedIOException;
+import java.net.URL;
 import java.nio.file.Path;
 import java.nio.file.Paths;
 import java.util.Arrays;
@@ -129,8 +130,16 @@ void usingClasspathStarProtocolWithWildcardInPatternAndEndingInSlash() throws Ex
 
 				List<String> actualSubPaths = getSubPathsIgnoringClassFilesEtc(pattern, pathPrefix);
 
-				// We do NOT find "support" if the pattern ENDS with a slash.
-				assertThat(actualSubPaths).isEmpty();
+				URL url = getClass().getClassLoader().getResource("org/springframework/core/io/support/EncodedResource.class");
+				if (!url.getProtocol().equals("jar")) {
+					// We do NOT find "support" if the pattern ENDS with a slash if org/springframework/core/io/support
+					// is in the local file system.
+					assertThat(actualSubPaths).isEmpty();
+				}
+				else {
+					// But we do find "support/" if org/springframework/core/io/support is found in a JAR on the classpath.
+					assertThat(actualSubPaths).containsExactly("support/");
+				}
 			}
 
 			@Test
@@ -258,6 +267,7 @@ private void assertFilenames(String pattern, boolean exactly, String... filename
 		try {
 			Resource[] resources = resolver.getResources(pattern);
 			List<String> actualNames = Arrays.stream(resources)
+					.peek(resource -> assertThat(resource.exists()).as(resource + " exists").isTrue())
 					.map(Resource::getFilename)
 					.sorted()
 					.toList();
@@ -304,7 +314,16 @@ private String getPath(Resource resource) {
 		// GraalVM native image which cannot support Path#toFile.
 		//
 		// See: https://github.com/spring-projects/spring-framework/issues/29243
-		return ((FileSystemResource) resource).getPath();
+		if (resource instanceof FileSystemResource fileSystemResource) {
+			return fileSystemResource.getPath();
+		}
+		try {
+			// Fall back to URL in case the resource came from a JAR
+			return resource.getURL().getPath();
+		}
+		catch (IOException ex) {
+			throw new UncheckedIOException(ex);
+		}
 	}
 
 }