001    /**
002     * Licensed to the Apache Software Foundation (ASF) under one or more
003     * contributor license agreements.  See the NOTICE file distributed with
004     * this work for additional information regarding copyright ownership.
005     * The ASF licenses this file to You under the Apache License, Version 2.0
006     * (the "License"); you may not use this file except in compliance with
007     * the License.  You may obtain a copy of the License at
008     *
009     *      http://www.apache.org/licenses/LICENSE-2.0
010     *
011     * Unless required by applicable law or agreed to in writing, software
012     * distributed under the License is distributed on an "AS IS" BASIS,
013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014     * See the License for the specific language governing permissions and
015     * limitations under the License.
016     */
017    package org.apache.xbean.server.spring.reference;
018    
019    import java.io.Serializable;
020    
021    import org.springframework.beans.factory.support.RootBeanDefinition;
022    import org.springframework.beans.factory.config.BeanDefinitionHolder;
023    import org.springframework.beans.factory.FactoryBean;
024    import org.apache.xbean.kernel.Kernel;
025    import org.apache.xbean.kernel.ServiceContext;
026    import org.apache.xbean.kernel.ServiceContextThreadLocal;
027    
028    
029    /**
030     * KernelReference is a the kernel in the ServiceContextThreadLocal. 
031     * @author Dain Sundstrom
032     * @version $Id$
033     * @since 2.0
034     */
035    public class KernelReference implements FactoryBean, Serializable {
036        /**
037         * Creates a bean definition for KernelReference.
038         * @return a bean definition for KernelReference
039         */
040        public static BeanDefinitionHolder createBeanDefinition() {
041            RootBeanDefinition beanDefinition = new RootBeanDefinition(KernelReference.class, 0);
042            return new BeanDefinitionHolder(beanDefinition, KernelReference.class.getName());
043        }
044    
045        public final Class getObjectType() {
046            return Kernel.class;
047        }
048    
049        public synchronized final Object getObject() {
050            ServiceContext serviceContext = ServiceContextThreadLocal.get();
051            if (serviceContext == null) {
052                throw new IllegalStateException("Service context has not been set");
053            }
054            return serviceContext.getKernel();
055        }
056    
057        public boolean isSingleton() {
058            return true;
059        }
060    }