Check for the existence of any actual jar entries in case of jar root

Closes gh-34796

Author: jhoeller

spring-core/src/main/java/org/springframework/core/io/AbstractFileResolvingResource.java

@@ -86,7 +86,16 @@ else if (code == HttpURLConnection.HTTP_NOT_FOUND) {
 				if (con instanceof JarURLConnection jarCon) {
 					// For JarURLConnection, do not check content-length but rather the
 					// existence of the entry (or the jar root in case of no entryName).
-					return (jarCon.getEntryName() == null || jarCon.getJarEntry() != null);
+					try {
+						if (jarCon.getEntryName() == null) {
+							// Jar root: check for the existence of any actual jar entries.
+							return jarCon.getJarFile().entries().hasMoreElements();
+						}
+						return (jarCon.getJarEntry() != null);
+					}
+					finally {
+						jarCon.getJarFile().close();
+					}
 				}
 				else if (con.getContentLengthLong() > 0) {
 					return true;

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

@@ -335,6 +335,11 @@ private void writeAssetJar(Path path) throws Exception {
 			}
 			assertThat(new FileSystemResource(path).exists()).isTrue();
 			assertThat(new UrlResource(ResourceUtils.JAR_URL_PREFIX + ResourceUtils.FILE_URL_PREFIX + path + ResourceUtils.JAR_URL_SEPARATOR).exists()).isTrue();
+			assertThat(new UrlResource(ResourceUtils.JAR_URL_PREFIX + ResourceUtils.FILE_URL_PREFIX + path + ResourceUtils.JAR_URL_SEPARATOR + "assets/file.txt").exists()).isTrue();
+			assertThat(new UrlResource(ResourceUtils.JAR_URL_PREFIX + ResourceUtils.FILE_URL_PREFIX + path + ResourceUtils.JAR_URL_SEPARATOR + "assets/none.txt").exists()).isFalse();
+			assertThat(new UrlResource(ResourceUtils.JAR_URL_PREFIX + ResourceUtils.FILE_URL_PREFIX + "X" + path + ResourceUtils.JAR_URL_SEPARATOR).exists()).isFalse();
+			assertThat(new UrlResource(ResourceUtils.JAR_URL_PREFIX + ResourceUtils.FILE_URL_PREFIX + "X" + path + ResourceUtils.JAR_URL_SEPARATOR + "assets/file.txt").exists()).isFalse();
+			assertThat(new UrlResource(ResourceUtils.JAR_URL_PREFIX + ResourceUtils.FILE_URL_PREFIX + "X" + path + ResourceUtils.JAR_URL_SEPARATOR + "assets/none.txt").exists()).isFalse();
 		}
 
 		private void writeApplicationJar(Path path) throws Exception {