Treat URLs for same file in nested archive and from jar root as equal

Consider the following two URLs:

jar:file:/test.jar!/BOOT-INF/classes!/foo.txt
jar:file:/test.jar!/BOOT-INF/classes/foo.txt

They both reference the same foo.txt file in the BOOT-INF/classes
directory of test.jar, however the first URL does so via the
nested BOOT-INF/classes archive. Previously, this difference in the
URLs would lead to PathMatchingResourcePatternResolver returning two
resources for foo.txt when asked to find all resources matching the
pattern classpath*:/**/*.txt.

This commit updates our Handler that is used for jar: URLs to consider
the two URLs above to be equivalent such that url1 is equal to url2
and the two urls will produce the same hash code.

Closes gh-7449

Author: wilkinsona

spring-boot-tools/spring-boot-loader/src/main/java/org/springframework/boot/loader/jar/Handler.java

@@ -196,6 +196,30 @@ private void setFile(URL context, String file) {
 		setURL(context, JAR_PROTOCOL, null, -1, null, null, file, null, null);
 	}
 
+	@Override
+	protected int hashCode(URL u) {
+		int result = 0;
+		String protocol = u.getProtocol();
+		if (protocol != null) {
+			result += protocol.hashCode();
+		}
+		String file = u.getFile();
+		int separatorIndex = file.indexOf(SEPARATOR);
+		if (separatorIndex == -1) {
+			return result + file.hashCode();
+		}
+		String fileWithoutEntry = file.substring(0, separatorIndex);
+		try {
+			result += new URL(fileWithoutEntry).hashCode();
+		}
+		catch (MalformedURLException ex) {
+			result += fileWithoutEntry.hashCode();
+		}
+		String entry = canonicalize(file.substring(separatorIndex + 2));
+		result += entry.hashCode();
+		return result;
+	}
+
 	@Override
 	protected boolean sameFile(URL u1, URL u2) {
 		if (!u1.getProtocol().equals("jar") || !u2.getProtocol().equals("jar")) {
@@ -209,7 +233,11 @@ protected boolean sameFile(URL u1, URL u2) {
 		String nested1 = u1.getFile().substring(separator1 + SEPARATOR.length());
 		String nested2 = u2.getFile().substring(separator2 + SEPARATOR.length());
 		if (!nested1.equals(nested2)) {
-			return false;
+			String canonical1 = canonicalize(nested1);
+			String canonical2 = canonicalize(nested2);
+			if (!canonical1.equals(canonical2)) {
+				return false;
+			}
 		}
 		String root1 = u1.getFile().substring(0, separator1);
 		String root2 = u2.getFile().substring(0, separator2);
@@ -222,6 +250,10 @@ protected boolean sameFile(URL u1, URL u2) {
 		return super.sameFile(u1, u2);
 	}
 
+	private String canonicalize(String path) {
+		return path.replace(SEPARATOR, "/");
+	}
+
 	public JarFile getRootJarFileFromUrl(URL url) throws IOException {
 		String spec = url.getFile();
 		int separatorIndex = spec.indexOf(SEPARATOR);

spring-boot-tools/spring-boot-loader/src/test/java/org/springframework/boot/loader/jar/HandlerTests.java

@@ -119,6 +119,23 @@ public void sameFileReturnsTrueForSameFileInSameJar() throws MalformedURLExcepti
 				new URL("jar:file:/the/path/to/the/first.jar!/content.txt"))).isTrue();
 	}
 
+	@Test
+	public void sameFileReturnsTrueForUrlsThatReferenceSameFileViaNestedArchiveAndFromRootOfJar()
+			throws MalformedURLException {
+		assertThat(this.handler.sameFile(
+				new URL("jar:file:/test.jar!/BOOT-INF/classes!/foo.txt"),
+				new URL("jar:file:/test.jar!/BOOT-INF/classes/foo.txt"))).isTrue();
+	}
+
+	@Test
+	public void hashcodesAreEqualForUrlsThatReferenceSameFileViaNestedArchiveAndFromRootOfJar()
+			throws MalformedURLException {
+		assertThat(this.handler
+				.hashCode(new URL("jar:file:/test.jar!/BOOT-INF/classes!/foo.txt")))
+						.isEqualTo(this.handler.hashCode(
+								new URL("jar:file:/test.jar!/BOOT-INF/classes/foo.txt")));
+	}
+
 	private URL createUrl(String file) throws MalformedURLException {
 		return new URL("jar", null, -1, file, this.handler);
 	}