| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you 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.apache.felix.example.extenderbased.host; |
| |
| import java.util.HashSet; |
| import java.util.Set; |
| import org.osgi.framework.Bundle; |
| import org.osgi.framework.BundleContext; |
| import org.osgi.framework.BundleEvent; |
| import org.osgi.framework.SynchronousBundleListener; |
| |
| /** |
| * This is a very simple bundle tracker utility class that tracks active |
| * bundles. The tracker must be given a bundle context upon creation, |
| * which it uses to listen for bundle events. The bundle tracker must be |
| * opened to track objects and closed when it is no longer needed. This |
| * class is abstract, which means in order to use it you must create a |
| * subclass of it. Subclasses must implement the <tt>addedBundle()</tt> |
| * and <tt>removedBundle()</tt> methods, which can be used to perform some |
| * custom action upon the activation or deactivation of bundles. Since this |
| * tracker is quite simple, its concurrency control approach is also |
| * simplistic. This means that subclasses should take great care to ensure |
| * that their <tt>addedBundle()</tt> and <tt>removedBundle()</tt> methods |
| * are very simple and do not do anything to change the state of any bundles. |
| **/ |
| public abstract class BundleTracker |
| { |
| final Set m_bundleSet = new HashSet(); |
| final BundleContext m_context; |
| final SynchronousBundleListener m_listener; |
| boolean m_open; |
| |
| /** |
| * Constructs a bundle tracker object that will use the specified |
| * bundle context. |
| * @param context The bundle context to use to track bundles. |
| **/ |
| public BundleTracker(BundleContext context) |
| { |
| m_context = context; |
| m_listener = new SynchronousBundleListener() { |
| public void bundleChanged(BundleEvent evt) |
| { |
| synchronized (BundleTracker.this) |
| { |
| if (!m_open) |
| { |
| return; |
| } |
| |
| if (evt.getType() == BundleEvent.STARTED) |
| { |
| if (!m_bundleSet.contains(evt.getBundle())) |
| { |
| m_bundleSet.add(evt.getBundle()); |
| addedBundle(evt.getBundle()); |
| } |
| } |
| else if (evt.getType() == BundleEvent.STOPPED) |
| { |
| if (m_bundleSet.contains(evt.getBundle())) |
| { |
| m_bundleSet.remove(evt.getBundle()); |
| removedBundle(evt.getBundle()); |
| } |
| } |
| } |
| } |
| }; |
| } |
| |
| /** |
| * Returns the current set of active bundles. |
| * @return The current set of active bundles. |
| **/ |
| public synchronized Bundle[] getBundles() |
| { |
| return (Bundle[]) m_bundleSet.toArray(new Bundle[m_bundleSet.size()]); |
| } |
| |
| /** |
| * Call this method to start the tracking of active bundles. |
| **/ |
| public synchronized void open() |
| { |
| if (!m_open) |
| { |
| m_open = true; |
| |
| m_context.addBundleListener(m_listener); |
| |
| Bundle[] bundles = m_context.getBundles(); |
| for (int i = 0; i < bundles.length; i++) |
| { |
| if (bundles[i].getState() == Bundle.ACTIVE) |
| { |
| m_bundleSet.add(bundles[i]); |
| addedBundle(bundles[i]); |
| } |
| } |
| } |
| } |
| |
| /** |
| * Call this method to stop the tracking of active bundles. |
| **/ |
| public synchronized void close() |
| { |
| if (m_open) |
| { |
| m_open = false; |
| |
| m_context.removeBundleListener(m_listener); |
| |
| Bundle[] bundles = (Bundle[]) m_bundleSet.toArray(new Bundle[m_bundleSet.size()]); |
| for (int i = 0; i < bundles.length; i++) |
| { |
| if (m_bundleSet.remove(bundles[i])) |
| { |
| removedBundle(bundles[i]); |
| } |
| } |
| } |
| } |
| |
| /** |
| * Subclasses must implement this method; it can be used to perform |
| * actions upon the activation of a bundle. Subclasses should keep |
| * this method implementation as simple as possible and should not |
| * cause the change in any bundle state to avoid concurrency issues. |
| * @param bundle The bundle being added to the active set. |
| **/ |
| protected abstract void addedBundle(Bundle bundle); |
| |
| /** |
| * Subclasses must implement this method; it can be used to perform |
| * actions upon the deactivation of a bundle. Subclasses should keep |
| * this method implementation as simple as possible and should not |
| * cause the change in any bundle state to avoid concurrency issues. |
| * @param bundle The bundle being removed from the active set. |
| **/ |
| protected abstract void removedBundle(Bundle bundle); |
| } |