Extended PropertiesLauncher class location logic

Update `PropertiesLauncher` so that classes can be loaded outside of
`BOOT-INF/classes`. You can use a subdirectory, or the root directory
of an external jar (but not the parent archive to avoid issues
with agents and awkward delegation models).

Fixes gh-8480
Closes gh-8486

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/web/WebMvcAutoConfiguration.java

@@ -735,7 +735,7 @@ public class WebMvcAutoConfiguration {
 	static class DelegatingWebMvcValidator extends DelegatingValidator
 			implements ApplicationContextAware, InitializingBean, DisposableBean {
 
-		public DelegatingWebMvcValidator(Validator targetValidator) {
+		DelegatingWebMvcValidator(Validator targetValidator) {
 			super(targetValidator);
 		}
 

spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/validation/DelegatingValidatorTests.java

@@ -99,7 +99,6 @@ public class DelegatingValidatorTests {
 		Object[] hints = { "foo", "bar" };
 		this.delegating.validate(target, errors, hints);
 		verify(this.delegate).validate(target, errors, hints);
-		;
 	}
 
 	@Test

spring-boot-docs/src/main/asciidoc/appendix-executable-jar-format.adoc

@@ -283,6 +283,8 @@ the `Main-Class` attribute and leave out `Start-Class`.
 * `loader.path` can contain directories (scanned recursively for jar and zip files),
   archive paths, a directory within an archive that is scanned for jar files (for
   example, `dependencies.jar!/lib`), or wildcard patterns (for the default JVM behavior).
+  Archive paths can be relative to `loader.home`, or anywhere in the file system with a
+  `jar:file:` prefix.
 * `loader.path` (if empty) defaults to `BOOT-INF/lib` (meaning a local directory or a
   nested one if running from an archive). Because of this `PropertiesLauncher` behaves the
   same as `JarLauncher` when no additional configuration is provided.

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

@@ -25,8 +25,10 @@ import java.net.URL;
 import java.net.URLConnection;
 import java.util.ArrayList;
 import java.util.Collections;
+import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Properties;
+import java.util.Set;
 import java.util.jar.Manifest;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
@@ -299,11 +301,9 @@ public class PropertiesLauncher extends Launcher {
 		List<String> paths = new ArrayList<String>();
 		for (String path : commaSeparatedPaths.split(",")) {
 			path = cleanupPath(path);
-			// Empty path (i.e. the archive itself if running from a JAR) is always added
-			// to the classpath so no need for it to be explicitly listed
-			if (!path.equals("")) {
-				paths.add(path);
-			}
+			// "" means the user wants root of archive but not current directory
+			path = ("".equals(path) ? "/" : path);
+			paths.add(path);
 		}
 		if (paths.isEmpty()) {
 			paths.add("lib");
@@ -336,7 +336,13 @@ public class PropertiesLauncher extends Launcher {
 
 	@Override
 	protected ClassLoader createClassLoader(List<Archive> archives) throws Exception {
-		ClassLoader loader = super.createClassLoader(archives);
+		Set<URL> urls = new LinkedHashSet<URL>(archives.size());
+		for (Archive archive : archives) {
+			urls.add(archive.getUrl());
+		}
+		ClassLoader loader = new LaunchedURLClassLoader(urls.toArray(new URL[0]),
+				getClass().getClassLoader());
+		debug("Classpath: " + urls);
 		String customLoaderClassName = getProperty("loader.classLoader");
 		if (customLoaderClassName != null) {
 			loader = wrapWithCustomClassLoader(loader, customLoaderClassName);
@@ -454,13 +460,15 @@ public class PropertiesLauncher extends Launcher {
 		String root = cleanupPath(stripFileUrlPrefix(path));
 		List<Archive> lib = new ArrayList<Archive>();
 		File file = new File(root);
-		if (!isAbsolutePath(root)) {
-			file = new File(this.home, root);
-		}
-		if (file.isDirectory()) {
-			debug("Adding classpath entries from " + file);
-			Archive archive = new ExplodedArchive(file, false);
-			lib.add(archive);
+		if (!"/".equals(root)) {
+			if (!isAbsolutePath(root)) {
+				file = new File(this.home, root);
+			}
+			if (file.isDirectory()) {
+				debug("Adding classpath entries from " + file);
+				Archive archive = new ExplodedArchive(file, false);
+				lib.add(archive);
+			}
 		}
 		Archive archive = getArchive(file);
 		if (archive != null) {
@@ -488,24 +496,46 @@ public class PropertiesLauncher extends Launcher {
 		return null;
 	}
 
-	private List<Archive> getNestedArchives(String root) throws Exception {
-		if (root.startsWith("/")
-				|| this.parent.getUrl().equals(this.home.toURI().toURL())) {
+	private List<Archive> getNestedArchives(String path) throws Exception {
+		Archive parent = this.parent;
+		String root = path;
+		if (!root.equals("/") && root.startsWith("/")
+				|| parent.getUrl().equals(this.home.toURI().toURL())) {
 			// If home dir is same as parent archive, no need to add it twice.
 			return null;
 		}
-		Archive parent = this.parent;
-		if (root.startsWith("jar:file:") && root.contains("!")) {
+		if (root.contains("!")) {
 			int index = root.indexOf("!");
-			String file = root.substring("jar:file:".length(), index);
-			parent = new JarFileArchive(new File(file));
+			File file = new File(this.home, root.substring(0, index));
+			if (root.startsWith("jar:file:")) {
+				file = new File(root.substring("jar:file:".length(), index));
+			}
+			parent = new JarFileArchive(file);
 			root = root.substring(index + 1, root.length());
 			while (root.startsWith("/")) {
 				root = root.substring(1);
 			}
 		}
+		if (root.endsWith(".jar")) {
+			File file = new File(this.home, root);
+			if (file.exists()) {
+				parent = new JarFileArchive(file);
+				root = "";
+			}
+		}
+		if (root.equals("/") || root.equals("./") || root.equals(".")) {
+			// The prefix for nested jars is actually empty if it's at the root
+			root = "";
+		}
 		EntryFilter filter = new PrefixMatchingArchiveFilter(root);
-		return parent.getNestedArchives(filter);
+		List<Archive> archives = new ArrayList<Archive>(parent.getNestedArchives(filter));
+		if (("".equals(root) || ".".equals(root)) && !path.endsWith(".jar")
+				&& parent != this.parent) {
+			// You can't find the root with an entry filter so it has to be added
+			// explicitly. But don't add the root of the parent archive.
+			archives.add(parent);
+		}
+		return archives;
 	}
 
 	private void addNestedEntries(List<Archive> lib) {
@@ -518,7 +548,7 @@ public class PropertiesLauncher extends Launcher {
 				@Override
 				public boolean matches(Entry entry) {
 					if (entry.isDirectory()) {
-						return entry.getName().startsWith(JarLauncher.BOOT_INF_CLASSES);
+						return entry.getName().equals(JarLauncher.BOOT_INF_CLASSES);
 					}
 					return entry.getName().startsWith(JarLauncher.BOOT_INF_LIB);
 				}
@@ -607,6 +637,9 @@ public class PropertiesLauncher extends Launcher {
 
 		@Override
 		public boolean matches(Entry entry) {
+			if (entry.isDirectory()) {
+				return entry.getName().equals(this.prefix);
+			}
 			return entry.getName().startsWith(this.prefix) && this.filter.matches(entry);
 		}
 

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

@@ -21,12 +21,13 @@ import java.io.FileOutputStream;
 import java.io.IOException;
 import java.net.URL;
 import java.net.URLClassLoader;
+import java.util.ArrayList;
 import java.util.Arrays;
-import java.util.Collections;
 import java.util.List;
 import java.util.jar.Attributes;
 import java.util.jar.Manifest;
 
+import org.assertj.core.api.Condition;
 import org.junit.After;
 import org.junit.Before;
 import org.junit.Rule;
@@ -36,6 +37,9 @@ import org.junit.rules.TemporaryFolder;
 import org.mockito.MockitoAnnotations;
 
 import org.springframework.boot.loader.archive.Archive;
+import org.springframework.boot.loader.archive.ExplodedArchive;
+import org.springframework.boot.loader.archive.JarFileArchive;
+import org.springframework.core.io.FileSystemResource;
 import org.springframework.test.util.ReflectionTestUtils;
 
 import static org.assertj.core.api.Assertions.assertThat;
@@ -72,6 +76,7 @@ public class PropertiesLauncherTests {
 		System.clearProperty("loader.config.name");
 		System.clearProperty("loader.config.location");
 		System.clearProperty("loader.system");
+		System.clearProperty("loader.classLoader");
 	}
 
 	@Test
@@ -131,6 +136,16 @@ public class PropertiesLauncherTests {
 				.isEqualTo("[.]");
 	}
 
+	@Test
+	public void testUserSpecifiedSlashPath() throws Exception {
+		System.setProperty("loader.path", "jars/");
+		PropertiesLauncher launcher = new PropertiesLauncher();
+		assertThat(ReflectionTestUtils.getField(launcher, "paths").toString())
+				.isEqualTo("[jars/]");
+		List<Archive> archives = launcher.getClassPathArchives();
+		assertThat(archives).areExactly(1, endingWith("app.jar!/"));
+	}
+
 	@Test
 	public void testUserSpecifiedWildcardPath() throws Exception {
 		System.setProperty("loader.path", "jars/*");
@@ -153,13 +168,44 @@ public class PropertiesLauncherTests {
 		waitFor("Hello World");
 	}
 
+	@Test
+	public void testUserSpecifiedRootOfJarPath() throws Exception {
+		System.setProperty("loader.path",
+				"jar:file:./src/test/resources/nested-jars/app.jar!/");
+		PropertiesLauncher launcher = new PropertiesLauncher();
+		assertThat(ReflectionTestUtils.getField(launcher, "paths").toString())
+				.isEqualTo("[jar:file:./src/test/resources/nested-jars/app.jar!/]");
+		List<Archive> archives = launcher.getClassPathArchives();
+		assertThat(archives).areExactly(1, endingWith("foo.jar!/"));
+		assertThat(archives).areExactly(1, endingWith("app.jar!/"));
+	}
+
+	@Test
+	public void testUserSpecifiedRootOfJarPathWithDot() throws Exception {
+		System.setProperty("loader.path", "nested-jars/app.jar!/./");
+		PropertiesLauncher launcher = new PropertiesLauncher();
+		List<Archive> archives = launcher.getClassPathArchives();
+		assertThat(archives).areExactly(1, endingWith("foo.jar!/"));
+		assertThat(archives).areExactly(1, endingWith("app.jar!/"));
+	}
+
+	@Test
+	public void testUserSpecifiedRootOfJarPathWithDotAndJarPrefix() throws Exception {
+		System.setProperty("loader.path",
+				"jar:file:./src/test/resources/nested-jars/app.jar!/./");
+		PropertiesLauncher launcher = new PropertiesLauncher();
+		List<Archive> archives = launcher.getClassPathArchives();
+		assertThat(archives).areExactly(1, endingWith("foo.jar!/"));
+	}
+
 	@Test
 	public void testUserSpecifiedJarFileWithNestedArchives() throws Exception {
 		System.setProperty("loader.path", "nested-jars/app.jar");
 		System.setProperty("loader.main", "demo.Application");
 		PropertiesLauncher launcher = new PropertiesLauncher();
-		launcher.launch(new String[0]);
-		waitFor("Hello World");
+		List<Archive> archives = launcher.getClassPathArchives();
+		assertThat(archives).areExactly(1, endingWith("foo.jar!/"));
+		assertThat(archives).areExactly(1, endingWith("app.jar!/"));
 	}
 
 	@Test
@@ -209,11 +255,28 @@ public class PropertiesLauncherTests {
 	public void testCustomClassLoaderCreation() throws Exception {
 		System.setProperty("loader.classLoader", TestLoader.class.getName());
 		PropertiesLauncher launcher = new PropertiesLauncher();
-		ClassLoader loader = launcher.createClassLoader(Collections.<Archive>emptyList());
+		ClassLoader loader = launcher.createClassLoader(archives());
 		assertThat(loader).isNotNull();
 		assertThat(loader.getClass().getName()).isEqualTo(TestLoader.class.getName());
 	}
 
+	private List<Archive> archives() throws Exception {
+		List<Archive> archives = new ArrayList<Archive>();
+		String path = System.getProperty("java.class.path");
+		for (String url : path.split(File.pathSeparator)) {
+			archives.add(archive(url));
+		}
+		return archives;
+	}
+
+	private Archive archive(String url) throws IOException {
+		File file = new FileSystemResource(url).getFile();
+		if (url.endsWith(".jar")) {
+			return new JarFileArchive(file);
+		}
+		return new ExplodedArchive(file);
+	}
+
 	@Test
 	public void testUserSpecifiedConfigPathWins() throws Exception {
 
@@ -280,6 +343,17 @@ public class PropertiesLauncherTests {
 		assertThat(timeout).as("Timed out waiting for (" + value + ")").isTrue();
 	}
 
+	private Condition<Archive> endingWith(final String value) {
+		return new Condition<Archive>() {
+
+			@Override
+			public boolean matches(Archive archive) {
+				return archive.toString().endsWith(value);
+			}
+
+		};
+	}
+
 	public static class TestLoader extends URLClassLoader {
 
 		public TestLoader(ClassLoader parent) {