MetaServiceCaller.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.config.core.impl;

import org.osgi.framework.BundleContext;
import org.osgi.framework.ServiceReference;
import org.osgi.service.metatype.MetaTypeService;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Allows to use the MetaTypeService as an optional dependency
 */
public class MetaServiceCaller {
    private static Logger LOG = LoggerFactory.getLogger(MetaServiceCaller.class);

    public static <T> T withMetaTypeService(BundleContext context, MetatypeCallable<T> callable) {
        try {
            ServiceReference<MetaTypeService> ref = context.getServiceReference(MetaTypeService.class);
            try {
                MetaTypeService metaService = context.getService(ref);
                return callable.callWith(metaService);
            } finally {
                context.ungetService(ref);
            }
        } catch (NoClassDefFoundError e) {
            LOG.warn("No Metatype Service present");
            return null;
        }
    }
}