examples/karaf-servlet-example/karaf-servlet-example-registration/src/main/java/org/apache/karaf/examples/servlet/registration/Activator.java

/*
 *  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.karaf.examples.servlet.registration;

import org.osgi.framework.BundleActivator;
import org.osgi.framework.BundleContext;
import org.osgi.framework.ServiceReference;
import org.osgi.service.http.HttpService;
import org.osgi.util.tracker.ServiceTracker;

public class Activator implements BundleActivator {

    private ServiceTracker httpServiceTracker;

    @Override
    public void start(BundleContext bundleContext) throws Exception {
        httpServiceTracker = new ServiceTracker(bundleContext, HttpService.class.getName(), null) {
            @Override
            public Object addingService(ServiceReference ref) {
                HttpService httpService = (HttpService) bundleContext.getService(ref);
                try {
                    httpService.registerServlet("/servlet-example", new ExampleServlet(), null, null);
                } catch (Exception e) {
                    throw new RuntimeException(e);
                }
                return httpService;
            }

            public void removedService(ServiceReference ref, Object service) {
                try {
                    ((HttpService) service).unregister("/servlet-example");
                } catch (Exception e) {
                    throw new RuntimeException(e);
                }
            }
        };
        httpServiceTracker.open();
    }

    @Override
    public void stop(BundleContext bundleContext) throws Exception {
        httpServiceTracker.close();
    }

}