check that a java type is an ExtensionPoint

diff --git a/pf4j/src/main/java/ro/fortsoft/pf4j/DefaultExtensionFinder.java b/pf4j/src/main/java/ro/fortsoft/pf4j/DefaultExtensionFinder.java
index f61195bcec8b0ed9b07144827cfa4e74b3572f8d..86f11fcb15a6bee8838b2f23b01d4e8c52fd7dbf 100644 (file)
--- a/pf4j/src/main/java/ro/fortsoft/pf4j/DefaultExtensionFinder.java
+++ b/pf4j/src/main/java/ro/fortsoft/pf4j/DefaultExtensionFinder.java
@@ -48,7 +48,14 @@ public class DefaultExtensionFinder implements ExtensionFinder {
        
        @Override
        public <T> List<ExtensionWrapper<T>> find(Class<T> type) {
-               log.debug("Find extensions for extension point {}", type.getName());
+        log.debug("Checking extension point '{}'", type.getName());
+        if (!isExtensionPoint(type)) {
+            log.warn("'{}' is not an extension point", type.getName());
+
+            return Collections.emptyList(); // or return null ?!
+        }
+
+               log.debug("Finding extensions for extension point '{}'", type.getName());
         List<ExtensionWrapper<T>> result = new ArrayList<ExtensionWrapper<T>>();
         if (entries == null) {
                entries = readIndexFiles();
@@ -57,16 +64,16 @@ public class DefaultExtensionFinder implements ExtensionFinder {
         for (String entry : entries) {
                try {
                        Class<?> extensionType = classLoader.loadClass(entry);
-                       log.debug("Checking extension type {}", extensionType.getName());
+                       log.debug("Checking extension type '{}'", extensionType.getName());
                if (type.isAssignableFrom(extensionType)) {
                     Object instance = extensionFactory.create(extensionType);
                     if (instance != null) {
                                Extension extension = extensionType.getAnnotation(Extension.class);
-                               log.debug("Added extension {} with ordinal {}", extensionType.getName(), extension.ordinal());
+                               log.debug("Added extension '{}' with ordinal {}", extensionType.getName(), extension.ordinal());
                                result.add(new ExtensionWrapper<T>(type.cast(instance), extension.ordinal()));
                     }
                } else {
-                       log.warn("{} is not an extension for extension point {}", extensionType.getName(), type.getName());
+                       log.warn("'{}' is not an extension for extension point '{}'", extensionType.getName(), type.getName());
                }
                } catch (ClassNotFoundException e) {
                        log.error(e.getMessage(), e);           
@@ -74,9 +81,9 @@ public class DefaultExtensionFinder implements ExtensionFinder {
         }
         
         if (entries.isEmpty()) {
-               log.debug("No extensions found for extension point {}", type.getName());
+               log.debug("No extensions found for extension point '{}'", type.getName());
         } else {
-               log.debug("Found {} extensions for extension point {}", entries.size(), type.getName());
+               log.debug("Found {} extensions for extension point '{}'", entries.size(), type.getName());
         }
 
         // sort by "ordinal" property
@@ -94,7 +101,7 @@ public class DefaultExtensionFinder implements ExtensionFinder {
                        
                        @Override
                        public Object create(Class<?> extensionType) {
-                               log.debug("Create instance for extension {}", extensionType.getName());
+                               log.debug("Create instance for extension '{}'", extensionType.getName());
                                
                                try {
                                        return extensionType.newInstance();
@@ -131,7 +138,11 @@ public class DefaultExtensionFinder implements ExtensionFinder {
         }
 
                return entries;
-       }       
+       }
+
+    private boolean isExtensionPoint(Class type) {
+        return ExtensionPoint.class.isAssignableFrom(type);
+    }
        
        /**
         * Creates an extension instance.