1 files changed, 80 insertions, 0 deletions
diff --git a/src/main/java/org/traccar/helper/ClassScanner.java b/src/main/java/org/traccar/helper/ClassScanner.java
new file mode 100644
index 000000000..c928f6a12
--- /dev/null
+++ b/src/main/java/org/traccar/helper/ClassScanner.java
@@ -0,0 +1,80 @@
+/*
+ * Copyright 2022 Anton Tananaev (anton@traccar.org)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.traccar.helper;
+
+import java.io.File;
+import java.io.IOException;
+import java.net.URI;
+import java.net.URISyntaxException;
+import java.net.URL;
+import java.net.URLDecoder;
+import java.nio.charset.StandardCharsets;
+import java.util.Enumeration;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.jar.JarEntry;
+import java.util.jar.JarFile;
+
+public final class ClassScanner {
+
+    private ClassScanner() {
+    }
+
+    public static List<Class<?>> findSubclasses(
+            Class<?> baseClass) throws IOException, URISyntaxException, ReflectiveOperationException {
+        return findSubclasses(baseClass, baseClass.getPackageName());
+    }
+
+    public static List<Class<?>> findSubclasses(Class<?> baseClass, String packageName)
+            throws IOException, URISyntaxException, ReflectiveOperationException {
+
+        List<String> names = new LinkedList<>();
+        String packagePath = packageName.replace('.', '/');
+        URL packageUrl = baseClass.getClassLoader().getResource(packagePath);
+
+        if (packageUrl.getProtocol().equals("jar")) {
+            String jarFileName = URLDecoder.decode(packageUrl.getFile(), StandardCharsets.UTF_8.name());
+            try (JarFile jf = new JarFile(jarFileName.substring(5, jarFileName.indexOf("!")))) {
+                Enumeration<JarEntry> jarEntries = jf.entries();
+                while (jarEntries.hasMoreElements()) {
+                    String entryName = jarEntries.nextElement().getName();
+                    if (entryName.startsWith(packagePath) && entryName.length() > packagePath.length() + 5) {
+                        names.add(entryName.substring(packagePath.length() + 1, entryName.lastIndexOf('.')));
+                    }
+                }
+            }
+        } else {
+            File folder = new File(new URI(packageUrl.toString()));
+            File[] files = folder.listFiles();
+            if (files != null) {
+                for (File actual: files) {
+                    String entryName = actual.getName();
+                    names.add(entryName.substring(0, entryName.lastIndexOf('.')));
+                }
+            }
+        }
+
+        var classes = new LinkedList<Class<?>>();
+        for (String name : names) {
+            var clazz = Class.forName(packageName + '.' + name);
+            if (baseClass.isAssignableFrom(clazz)) {
+                classes.add(clazz);
+            }
+        }
+        return classes;
+    }
+
+}