add possibility to override extension creation in DefaultExtensionFinder

diff --git a/pf4j/src/main/java/ro/fortsoft/pf4j/DefaultExtensionFinder.java b/pf4j/src/main/java/ro/fortsoft/pf4j/DefaultExtensionFinder.java
index 5ab989b6a7ed5de73f63691005085070f2127c2d..f61195bcec8b0ed9b07144827cfa4e74b3572f8d 100644 (file)
--- a/pf4j/src/main/java/ro/fortsoft/pf4j/DefaultExtensionFinder.java
+++ b/pf4j/src/main/java/ro/fortsoft/pf4j/DefaultExtensionFinder.java
@@ -38,10 +38,12 @@ public class DefaultExtensionFinder implements ExtensionFinder {
        private static final Logger log = LoggerFactory.getLogger(DefaultExtensionFinder.class);
        
        private ClassLoader classLoader;
+       private ExtensionFactory extensionFactory;
        private volatile Set<String> entries;
        
        public DefaultExtensionFinder(ClassLoader classLoader) {
                this.classLoader = classLoader;
+               this.extensionFactory = createExtensionFactory();
        }
        
        @Override
@@ -57,21 +59,17 @@ public class DefaultExtensionFinder implements ExtensionFinder {
                        Class<?> extensionType = classLoader.loadClass(entry);
                        log.debug("Checking extension type {}", extensionType.getName());
                if (type.isAssignableFrom(extensionType)) {
-                    Object instance = extensionType.newInstance();
+                    Object instance = extensionFactory.create(extensionType);
                     if (instance != null) {
                                Extension extension = extensionType.getAnnotation(Extension.class);
-                               log.debug("Added extension {} with ordinal {}", extensionType, 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, type.getName());
+                       log.warn("{} is not an extension for extension point {}", extensionType.getName(), type.getName());
                }
                } catch (ClassNotFoundException e) {
-                       log.error(e.getMessage(), e);
-               } catch (InstantiationException e) {
-                       log.error(e.getMessage(), e);
-                       } catch (IllegalAccessException e) {
-                               log.error(e.getMessage(), e);
+                       log.error(e.getMessage(), e);           
                        }
         }
         
@@ -87,6 +85,31 @@ public class DefaultExtensionFinder implements ExtensionFinder {
                return result;
        }
        
+       /**
+     * Add the possibility to override the ExtensionFactory.
+     * The default implementation uses Class.newInstance() method.
+     */
+       protected ExtensionFactory createExtensionFactory() {
+               return new ExtensionFactory() {
+                       
+                       @Override
+                       public Object create(Class<?> extensionType) {
+                               log.debug("Create instance for extension {}", extensionType.getName());
+                               
+                               try {
+                                       return extensionType.newInstance();
+                               } catch (InstantiationException e) {
+                                       log.error(e.getMessage(), e);
+                               } catch (IllegalAccessException e) {
+                                       log.error(e.getMessage(), e);
+                               }
+                               
+                               return null;
+                       }
+                       
+               };
+       }
+       
        private Set<String> readIndexFiles() {
                log.debug("Reading extensions index files");
                Set<String> entries = new HashSet<String>();
@@ -110,4 +133,13 @@ public class DefaultExtensionFinder implements ExtensionFinder {
                return entries;
        }       
        
+       /**
+        * Creates an extension instance.
+        */
+       public static interface ExtensionFactory {
+
+               public Object create(Class<?> extensionType);
+               
+       }
+
 }