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CustomGenericDefaultServiceObservingProvidility.java
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CustomGenericDefaultServiceObservingProvidility.java
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/*
* Copyright 2017 Leonhard Riedißer
*
* 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 de.l7r7.proto.bundle.magic.util;
import org.osgi.framework.*;
import org.osgi.util.tracker.ServiceTracker;
import java.util.Optional;
import java.util.function.Consumer;
public class CustomGenericDefaultServiceObservingProvidility<T> {
private BundleContext context;
private Consumer<Optional<T>> consumer;
private ServiceListener listener;
private ServiceTracker<T, T> serviceTracker;
private ServiceReference<T> serviceReference;
public void start(BundleContext bundleContext, Class<T> clazz, Consumer<Optional<T>> consumer) throws InvalidSyntaxException {
this.context = bundleContext;
this.consumer = consumer;
serviceTracker = new ServiceTracker<>(bundleContext, clazz.getName(), null);
serviceTracker.open();
serviceReference = serviceTracker.getServiceReference();
if (serviceReference != null) {
final T service = bundleContext.getService(serviceReference);
consumer.accept(Optional.ofNullable(service));
} else {
consumer.accept(Optional.empty());
}
listener = event -> {
switch (event.getType()) {
case ServiceEvent.REGISTERED:
if (serviceReference == null) {
serviceReference = (ServiceReference<T>) event.getServiceReference();
}
final T service = bundleContext.getService(serviceReference);
consumer.accept(Optional.ofNullable(service));
break;
case ServiceEvent.UNREGISTERING:
cleanup(bundleContext);
break;
}
};
bundleContext.addServiceListener(listener, "(objectclass=" + clazz.getName() + ")");
}
private void cleanup(BundleContext context) {
consumer.accept(Optional.empty());
if (serviceReference != null) {
context.ungetService(serviceReference);
serviceReference = null;
}
}
public void stop() {
context.removeServiceListener(listener);
cleanup(context);
serviceTracker.close();
}
}