Removed depth when searching extension jars

qupath-gui-fx/src/main/java/qupath/lib/gui/ExtensionClassLoader.java

@@ -8,21 +8,20 @@
  * it under the terms of the GNU General Public License as
  * published by the Free Software Foundation, either version 3 of the
  * License, or (at your option) any later version.
- * 
+ *
  * QuPath is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
- * 
- * You should have received a copy of the GNU General Public License 
+ *
+ * You should have received a copy of the GNU General Public License
  * along with QuPath.  If not, see <https://www.gnu.org/licenses/>.
  * #L%
  */
 
 package qupath.lib.gui;
 
 import java.io.IOException;
-import java.net.MalformedURLException;
 import java.net.URL;
 import java.net.URLClassLoader;
 import java.nio.file.FileVisitOption;
@@ -32,25 +31,23 @@
 import java.util.Objects;
 import java.util.Set;
 import java.util.function.Supplier;
+import java.util.stream.Stream;
 
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 /**
  * {@link ClassLoader} for loading QuPath extensions and other jars from the user directory.
- * 
+ *
  * @author Pete Bankhead
  */
 public class ExtensionClassLoader extends URLClassLoader {
 
 	private static final Logger logger = LoggerFactory.getLogger(ExtensionClassLoader.class);
-
+	private static int MAX_EXTENSION_JARS_DEPTH = 3;		// non-final to be editable with Groovy
 	private static ExtensionClassLoader INSTANCE = null;
-
-	private Supplier<Path> extensionsDirectorySupplier;
-
-	private Set<Path> loadedJars = new HashSet<>();
-
+	private final Supplier<Path> extensionsDirectorySupplier;
+	private final Set<Path> loadedJars = new HashSet<>();
 	private boolean isClosed = false;
 
 	private ExtensionClassLoader(Supplier<Path> extensionsDirectorySupplier) {
@@ -63,9 +60,9 @@ private ExtensionClassLoader(Supplier<Path> extensionsDirectorySupplier) {
 	 * Get a singleton instance of the {@link ExtensionClassLoader}.
 	 * @return
 	 * @since v0.5.0
-	 * 
-	 * @implNote This was introduced in v0.5.0 to hide the constructor and avoid needing to request 
-	 * the classloader via QuPathGUI. <i>However</i> the behavior may change in the future, so as to 
+	 *
+	 * @implNote This was introduced in v0.5.0 to hide the constructor and avoid needing to request
+	 * the classloader via QuPathGUI. <i>However</i> the behavior may change in the future, so as to
 	 * avoid relying upon a single static instance.
 	 */
 	public static ExtensionClassLoader getInstance() {
@@ -86,9 +83,9 @@ private static Path getDefaultExtensionsDirectory() {
 
 	/**
 	 * Directory containing extensions.
-	 * 
+	 *
 	 * This can contain any jars - all will be added to the search path when starting QuPath.
-	 * 
+	 *
 	 * @return
 	 */
 	public Path getExtensionsDirectory() {
@@ -106,24 +103,25 @@ public void refresh() {
 		}
 		if (!Files.exists(dirExtensions)) {
 			logger.debug("No extensions directory exists at {}", dirExtensions);
-			return;			
+			return;
 		}
 		if (!Files.isDirectory(dirExtensions)) {
 			logger.error("Invalid extensions directory! '{}' is not a directory.", dirExtensions);
 			return;
 		}
-		int depth = 1;
 		try {
-			Files.walk(dirExtensions, depth, FileVisitOption.FOLLOW_LINKS)
-				.filter(this::isJarFile)
-				.map(p -> p.toAbsolutePath())
-				.distinct()
-				.forEach(this::addJarFile);
+			try (Stream<Path> walk = Files.walk(dirExtensions, MAX_EXTENSION_JARS_DEPTH, FileVisitOption.FOLLOW_LINKS)) {
+				walk
+						.filter(this::isJarFile)
+						.map(Path::toAbsolutePath)
+						.distinct()
+						.forEach(this::addJarFile);
+			}
 		} catch (IOException e) {
 			logger.error("Exception refreshing extensions: " + e.getLocalizedMessage(), e);
 		}
 	}
-	
+
 	private void addJarFile(Path path) {
 		try {
 			if (loadedJars.add(path)) {
@@ -150,6 +148,5 @@ public void close() throws IOException {
 	private boolean isJarFile(Path path) {
 		return Files.isRegularFile(path) && path.getFileName().toString().toLowerCase().endsWith(".jar");
 	}
-
 
 }