org.apache.felix.eventadmin/src/main/java/org/apache/felix/eventadmin/impl/adapter/BundleEventAdapter.java

/*
 *   Copyright 2005 The Apache Software Foundation
 *
 *   Licensed 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.eventadmin.impl.adapter;

import java.util.Dictionary;
import java.util.Hashtable;

import org.osgi.framework.BundleContext;
import org.osgi.framework.BundleEvent;
import org.osgi.framework.BundleListener;
import org.osgi.service.event.Event;
import org.osgi.service.event.EventAdmin;
import org.osgi.service.event.EventConstants;

/**
 * This class registers itself as a listener for bundle events and posts them via
 * the EventAdmin as specified in 113.6.4 OSGi R4 compendium.
 * 
 * @author <a href="mailto:felix-dev@incubator.apache.org">Felix Project Team</a>
 */
public class BundleEventAdapter implements BundleListener
{
    private final EventAdmin m_admin;
    
    /**
     * The constructor of the adapter. This will register the adapter with the given
     * context as a <tt>BundleListener</tt> and subsequently, will post received 
     * events via the given EventAdmin.
     * 
     * @param context The bundle context with which to register as a listener.
     * @param admin The <tt>EventAdmin</tt> to use for posting events.
     */
    public BundleEventAdapter(final BundleContext context, final EventAdmin admin)
    {
        if(null == admin)
        {
            throw new NullPointerException("EventAdmin must not be null");
        }
        
        m_admin = admin;
        
        context.addBundleListener(this);
    }
    
    /**
     * Once a bundle event is received this method assembles and posts an event via
     * the <tt>EventAdmin</tt> as specified in 113.6.4 OSGi R4 compendium. 
     * 
     * @param event The event to adapt.
     */
    public void bundleChanged(final BundleEvent event)
    {
        final Dictionary properties = new Hashtable();

        properties.put(EventConstants.EVENT, event);

        properties.put("bundle.id", new Long(event.getBundle()
            .getBundleId()));

        final String symbolicName = event.getBundle().getSymbolicName();

        if (null != symbolicName)
        {
            properties.put(EventConstants.BUNDLE_SYMBOLICNAME,
                symbolicName);
        }

        properties.put("bundle", event.getBundle());

        final StringBuffer topic = new StringBuffer(BundleEvent.class
            .getName().replace('.', '/')).append('/');

        switch (event.getType())
        {
            case BundleEvent.INSTALLED:
                topic.append("INSTALLED");
                break;
            case BundleEvent.STARTED:
                topic.append("STARTED");
                break;
            case BundleEvent.STOPPED:
                topic.append("STOPPED");
                break;
            case BundleEvent.UPDATED:
                topic.append("UPDATED");
                break;
            case BundleEvent.UNINSTALLED:
                topic.append("UNINSTALLED");
                break;
            case BundleEvent.RESOLVED:
                topic.append("RESOLVED");
                break;
            case BundleEvent.UNRESOLVED:
                topic.append("UNRESOLVED");
                break;
            default:
                return; // IGNORE EVENT
        }

        try {
            m_admin.postEvent(new Event(topic.toString(), properties));
        } catch (IllegalStateException e) { 
            // This is o.k. - indicates that we are stopped.
        }
    }
}