add support for enabled (whitelist) plugins and disabled (blacklist) plugins

demo/disabled.txt

@@ -0,0 +1,6 @@
+########################################
+# - load all plugins except these
+# - add one plugin id on each line
+# - put this file in plugins folder
+########################################
+welcome-plugin

demo/enabled.txt

@@ -0,0 +1,6 @@
+########################################
+# - load only these plugins
+# - add one plugin id on each line
+# - put this file in plugins folder
+########################################
+welcome-plugin

pf4j/src/main/java/ro/fortsoft/pf4j/DefaultPluginManager.java

@@ -26,6 +26,7 @@ import org.slf4j.LoggerFactory;
 
 import ro.fortsoft.pf4j.util.CompoundClassLoader;
 import ro.fortsoft.pf4j.util.DirectoryFilter;
+import ro.fortsoft.pf4j.util.FileUtils;
 import ro.fortsoft.pf4j.util.Unzip;
 import ro.fortsoft.pf4j.util.ZipFilter;
 
@@ -72,16 +73,14 @@ public class DefaultPluginManager implements PluginManager {
      */
     private List<PluginWrapper> resolvedPlugins;
     
-    /**
-     * A list with disabled plugins.
-     */
-    private List<PluginWrapper> disabledPlugins;
-    
     /**
      * A list with started plugins.
      */
     private List<PluginWrapper> startedPlugins;
     
+    private List<String> enabledPlugins;
+    private List<String> disabledPlugins;
+    
     /**
      * A compound class loader of resolved plugins. 
      */
@@ -108,22 +107,26 @@ public class DefaultPluginManager implements PluginManager {
         pathToIdMap = new HashMap<String, String>();
         unresolvedPlugins = new ArrayList<PluginWrapper>();
         resolvedPlugins = new ArrayList<PluginWrapper>();
-        disabledPlugins = new ArrayList<PluginWrapper>();
         startedPlugins = new ArrayList<PluginWrapper>();
+        disabledPlugins = new ArrayList<String>();
         compoundClassLoader = new CompoundClassLoader();
         
         pluginDescriptorFinder = createPluginDescriptorFinder();
         extensionFinder = createExtensionFinder();
 
-        System.setProperty("pf4j.pluginsDir", pluginsDirectory.getAbsolutePath());
-    }
+        try {
+        	// create a list with plugin identifiers that should be only accepted by this manager (whitelist from plugins/enabled.txt file)
+        	enabledPlugins = FileUtils.readLines(new File(pluginsDirectory, "enabled.txt"), true);
+        	log.info("Enabled plugins: " + enabledPlugins);
         	
-    protected PluginDescriptorFinder createPluginDescriptorFinder() {
-    	return new DefaultPluginDescriptorFinder();
+        	// create a list with plugin identifiers that should not be accepted by this manager (blacklist from plugins/disabled.txt file)
+        	disabledPlugins = FileUtils.readLines(new File(pluginsDirectory, "disabled.txt"), true);
+        	log.info("Disabled plugins: " + disabledPlugins);
+        } catch (IOException e) {
+        	log.error(e.getMessage(), e);
         }
 
-    protected ExtensionFinder createExtensionFinder() {
-    	return new DefaultExtensionFinder(compoundClassLoader);
+        System.setProperty("pf4j.pluginsDir", pluginsDirectory.getAbsolutePath());
     }
 
 	@Override
@@ -145,10 +148,6 @@ public class DefaultPluginManager implements PluginManager {
 		return unresolvedPlugins;
 	}
 
-	public List<PluginWrapper> getDisabledPlugins() {
-		return disabledPlugins;
-	}
-
 	@Override
 	public List<PluginWrapper> getStartedPlugins() {
 		return startedPlugins;
@@ -211,9 +210,15 @@ public class DefaultPluginManager implements PluginManager {
 			}
         }
 
-        // load any plugin from plugins directory
+        // check for no plugins
         FilenameFilter directoryFilter = new DirectoryFilter();
         String[] directories = pluginsDirectory.list(directoryFilter);
+        if (directories.length == 0) {
+        	log.info("No plugins");
+        	return;
+        }
+
+        // load any plugin from plugins directory
         for (String directory : directories) {
             try {
                 loadPlugin(directory);
@@ -222,12 +227,6 @@ public class DefaultPluginManager implements PluginManager {
             }
         }
 
-        // check for no plugins
-        if (directories.length == 0) {
-        	log.info("No plugins");
-        	return;
-        }
-
         // resolve 'unresolvedPlugins'
         try {
 			resolvePlugins();
@@ -279,11 +278,6 @@ public class DefaultPluginManager implements PluginManager {
         // try to load the plugin
         String pluginPath = "/".concat(fileName);
 
-        // test for disabled plugin
-        if (disabledPlugins.contains(pluginPath)) {
-            return;
-        }
-
         // test for plugin duplication
         if (plugins.get(pathToIdMap.get(pluginPath)) != null) {
             return;
@@ -296,6 +290,12 @@ public class DefaultPluginManager implements PluginManager {
         String pluginClassName = pluginDescriptor.getPluginClass();
         log.debug("Class '" + pluginClassName + "'" + " for plugin '" + pluginPath + "'");
 
+        // test for disabled plugin
+        if (isPluginDisabled(pluginDescriptor.getPluginId())) {
+        	log.info("Plugin '" + pluginPath + "' is disabled");
+            return;
+        }
+
         // load plugin
         log.debug("Loading plugin '" + pluginPath + "'");
         PluginLoader pluginLoader = new PluginLoader(this, pluginDescriptor, pluginDirectory);
@@ -318,6 +318,28 @@ public class DefaultPluginManager implements PluginManager {
         pluginClassLoaders.put(pluginId, pluginClassLoader);
     }
 
+	/**
+	 * Add the possibility to override the PluginDescriptorFinder. 
+	 */
+    protected PluginDescriptorFinder createPluginDescriptorFinder() {
+    	return new DefaultPluginDescriptorFinder();
+    }
+
+    /**
+     * Add the possibility to override the ExtensionFinder. 
+     */
+    protected ExtensionFinder createExtensionFinder() {
+    	return new DefaultExtensionFinder(compoundClassLoader);
+    }
+
+    protected boolean isPluginDisabled(String pluginId) {
+    	if (enabledPlugins.isEmpty()) {
+    		return disabledPlugins.contains(pluginId);
+    	}
+    	
+    	return !enabledPlugins.contains(pluginId);
+    }
+    
     private void expandPluginArchive(String fileName) throws IOException {
         File pluginArchiveFile = new File(pluginsDirectory, fileName);
         long pluginArchiveDate = pluginArchiveFile.lastModified();

pf4j/src/main/java/ro/fortsoft/pf4j/util/FileUtils.java

@@ -0,0 +1,53 @@
+/*
+ * Copyright 2012 Decebal Suiu
+ * 
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this work except in compliance with
+ * the License. You may obtain a copy of the License in the LICENSE file, or 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 ro.fortsoft.pf4j.util;
+
+import java.io.BufferedReader;
+import java.io.File;
+import java.io.FileReader;
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
+/**
+ * @author Decebal Suiu
+ */
+public class FileUtils {
+
+	public static List<String> readLines(File file, boolean ignoreComments) throws IOException {		
+		if (!file.exists() || !file.isFile()) {
+			return Collections.emptyList();
+		}
+		
+		List<String> lines = new ArrayList<String>();
+
+		BufferedReader reader = null;
+		try {
+	        reader = new BufferedReader(new FileReader(file));
+			String line;
+			while ((line = reader.readLine()) != null) {
+				if (ignoreComments && !line.startsWith("#") && !lines.contains(line)) {
+					lines.add(line);
+				}
+			}
+		} finally {
+			if (reader != null) {
+				reader.close();
+			}
+		}
+		
+		return lines;
+	}
+	
+}