Add methods to start & stop a single plugin and it's dependencies

pf4j/pom.xml

@@ -32,6 +32,12 @@
             <artifactId>slf4j-api</artifactId>
             <version>1.6.4</version>
         </dependency>
+          <dependency>
+      <groupId>junit</groupId>
+      <artifactId>junit</artifactId>
+      <version>4.8.1</version>
+      <scope>test</scope>
+    </dependency>
     </dependencies>
 
 </project>

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

@@ -19,6 +19,7 @@ import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.HashMap;
+import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
 
@@ -163,6 +164,34 @@ public class DefaultPluginManager implements PluginManager {
         }
     }
 
+	/**
+     * Start the specified plugin and it's dependencies.
+     */
+    @Override
+    public PluginState startPlugin(String pluginId) {
+    	if (!plugins.containsKey(pluginId)) {
+    		throw new IllegalArgumentException(String.format("Unknown pluginId %s", pluginId));
+    	}
+    	PluginWrapper pluginWrapper = plugins.get(pluginId);
+    	PluginDescriptor pluginDescriptor = pluginWrapper.getDescriptor();
+    	if (pluginWrapper.getPluginState().equals(PluginState.STARTED)) {
+    		log.debug("Already started plugin '{}:{}'", pluginDescriptor.getPluginId(), pluginDescriptor.getVersion());
+    		return PluginState.STARTED;
+    	}
+    	for (PluginDependency dependency : pluginDescriptor.getDependencies()) {
+    		startPlugin(dependency.getPluginId());
+    	}
+    	try {
+    		log.info("Start plugin '{}:{}'", pluginDescriptor.getPluginId(), pluginDescriptor.getVersion());
+    		pluginWrapper.getPlugin().start();
+    		pluginWrapper.setPluginState(PluginState.STARTED);
+    		startedPlugins.add(pluginWrapper);
+    	} catch (PluginException e) {
+    		log.error(e.getMessage(), e);
+    	}
+    	return pluginWrapper.getPluginState();
+    }
+
     /**
      * Stop all active plugins.
      */
@@ -170,17 +199,49 @@ public class DefaultPluginManager implements PluginManager {
     public void stopPlugins() {
     	// stop started plugins in reverse order
     	Collections.reverse(startedPlugins);
-        for (PluginWrapper pluginWrapper : startedPlugins) {
+    	Iterator<PluginWrapper> itr = startedPlugins.iterator();
+        while (itr.hasNext()) {
+        	PluginWrapper pluginWrapper = itr.next();
+        	PluginDescriptor pluginDescriptor = pluginWrapper.getDescriptor();
             try {
-            	log.info("Stop plugin '{}'", pluginWrapper.getDescriptor().getPluginId());
+            	log.info("Stop plugin '{}:{}'", pluginDescriptor.getPluginId(), pluginDescriptor.getVersion());
             	pluginWrapper.getPlugin().stop();
             	pluginWrapper.setPluginState(PluginState.STOPPED);
+            	itr.remove();
 			} catch (PluginException e) {
 				log.error(e.getMessage(), e);
 			}
         }
     }
 
+    /**
+     * Stop the specified plugin and it's dependencies.
+     */
+    @Override
+    public PluginState stopPlugin(String pluginId) {
+    	if (!plugins.containsKey(pluginId)) {
+    		throw new IllegalArgumentException(String.format("Unknown pluginId %s", pluginId));
+    	}
+    	PluginWrapper pluginWrapper = plugins.get(pluginId);
+    	PluginDescriptor pluginDescriptor = pluginWrapper.getDescriptor();
+    	if (pluginWrapper.getPluginState().equals(PluginState.STOPPED)) {
+    		log.debug("Already stopped plugin '{}:{}'", pluginDescriptor.getPluginId(), pluginDescriptor.getVersion());
+    		return PluginState.STOPPED;
+    	}
+    	for (PluginDependency dependency : pluginDescriptor.getDependencies()) {
+    		stopPlugin(dependency.getPluginId());
+    	}
+    	try {
+    		log.info("Stop plugin '{}:{}'", pluginDescriptor.getPluginId(), pluginDescriptor.getVersion());
+    		pluginWrapper.getPlugin().stop();
+    		pluginWrapper.setPluginState(PluginState.STOPPED);
+    		startedPlugins.remove(pluginWrapper);
+    	} catch (PluginException e) {
+    		log.error(e.getMessage(), e);
+    	}
+    	return pluginWrapper.getPluginState();
+    }
+
     /**
      * Load plugins.
      */

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

@@ -52,11 +52,25 @@ public interface PluginManager {
      */
     public void startPlugins();
 
+    /**
+     * Start the specified plugin and it's dependencies.
+     *
+     * @return the plugin state
+     */
+    public PluginState startPlugin(String pluginId);
+
     /**
      * Stop all active plugins.
      */
     public void stopPlugins();
 
+    /**
+     * Stop the specified plugin and it's dependencies.
+     *
+     * @return the plugin state
+     */
+    public PluginState stopPlugin(String pluginId);
+
 	public PluginClassLoader getPluginClassLoader(String pluginId);
 
 	public <T> List<T> getExtensions(Class<T> type);