Update Devtools to ignore manifest Class-Path entries that do not exist

Closes gh-8623

Author: wilkinsona

spring-boot-devtools/src/main/java/org/springframework/boot/devtools/restart/ChangeableUrls.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2016 the original author or authors.
+ * Copyright 2012-2017 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.
@@ -96,7 +96,7 @@ private static List<URL> getUrlsFromClassPathOfJarManifestIfPossible(URL url) {
 			return Collections.<URL>emptyList();
 		}
 		try {
-			return getUrlsFromClassPathAttribute(url, jarFile.getManifest());
+			return getUrlsFromManifestClassPathAttribute(jarFile);
 		}
 		catch (IOException ex) {
 			throw new IllegalStateException(
@@ -118,7 +118,9 @@ private static JarFile getJarFileIfPossible(URL url) {
 		return null;
 	}
 
-	private static List<URL> getUrlsFromClassPathAttribute(URL base, Manifest manifest) {
+	private static List<URL> getUrlsFromManifestClassPathAttribute(JarFile jarFile)
+			throws IOException {
+		Manifest manifest = jarFile.getManifest();
 		if (manifest == null) {
 			return Collections.<URL>emptyList();
 		}
@@ -129,9 +131,18 @@ private static List<URL> getUrlsFromClassPathAttribute(URL base, Manifest manife
 		}
 		String[] entries = StringUtils.delimitedListToStringArray(classPath, " ");
 		List<URL> urls = new ArrayList<URL>(entries.length);
+		File parent = new File(jarFile.getName()).getParentFile();
 		for (String entry : entries) {
 			try {
-				urls.add(new URL(base, entry));
+				File referenced = new File(parent, entry);
+				if (referenced.exists()) {
+					urls.add(referenced.toURI().toURL());
+				}
+				else {
+					System.err.println("Ignoring Class-Path entry " + entry + " found in"
+							+ jarFile.getName() + " as " + referenced
+							+ " does not exist");
+				}
 			}
 			catch (MalformedURLException ex) {
 				throw new IllegalStateException(

spring-boot-devtools/src/test/java/org/springframework/boot/devtools/restart/ChangeableUrlsTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2016 the original author or authors.
+ * Copyright 2012-2017 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.
@@ -74,15 +74,19 @@ public void skipsUrls() throws Exception {
 
 	@Test
 	public void urlsFromJarClassPathAreConsidered() throws Exception {
-		URL projectCore = makeUrl("project-core");
-		URL projectWeb = makeUrl("project-web");
 		File relative = this.temporaryFolder.newFolder();
+		File jarWithClassPath = makeJarFileWithUrlsInManifestClassPath(
+				"project-core/target/classes/", "project-web/target/classes/",
+				"does-not-exist/target/classes", relative.getName() + "/");
+		new File(jarWithClassPath.getParentFile(), "project-core/target/classes")
+				.mkdirs();
+		new File(jarWithClassPath.getParentFile(), "project-web/target/classes").mkdirs();
 		ChangeableUrls urls = ChangeableUrls
 				.fromUrlClassLoader(new URLClassLoader(new URL[] {
-						makeJarFileWithUrlsInManifestClassPath(projectCore, projectWeb,
-								relative.getName() + "/"),
-						makeJarFileWithNoManifest() }));
-		assertThat(urls.toList()).containsExactly(projectCore, projectWeb,
+						jarWithClassPath.toURI().toURL(), makeJarFileWithNoManifest() }));
+		assertThat(urls.toList()).containsExactly(
+				new URL(jarWithClassPath.toURI().toURL(), "project-core/target/classes/"),
+				new URL(jarWithClassPath.toURI().toURL(), "project-web/target/classes/"),
 				relative.toURI().toURL());
 	}
 
@@ -95,15 +99,15 @@ private URL makeUrl(String name) throws IOException {
 		return file.toURI().toURL();
 	}
 
-	private URL makeJarFileWithUrlsInManifestClassPath(Object... urls) throws Exception {
+	private File makeJarFileWithUrlsInManifestClassPath(Object... urls) throws Exception {
 		File classpathJar = this.temporaryFolder.newFile("classpath.jar");
 		Manifest manifest = new Manifest();
 		manifest.getMainAttributes().putValue(Attributes.Name.MANIFEST_VERSION.toString(),
 				"1.0");
 		manifest.getMainAttributes().putValue(Attributes.Name.CLASS_PATH.toString(),
 				StringUtils.arrayToDelimitedString(urls, " "));
 		new JarOutputStream(new FileOutputStream(classpathJar), manifest).close();
-		return classpathJar.toURI().toURL();
+		return classpathJar;
 	}
 
 	private URL makeJarFileWithNoManifest() throws Exception {