001    // Copyright 2006, 2007, 2008, 2009, 2011 The Apache Software Foundation
002    //
003    // Licensed under the Apache License, Version 2.0 (the "License");
004    // you may not use this file except in compliance with the License.
005    // You may obtain a copy of the License at
006    //
007    // http://www.apache.org/licenses/LICENSE-2.0
008    //
009    // Unless required by applicable law or agreed to in writing, software
010    // distributed under the License is distributed on an "AS IS" BASIS,
011    // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012    // See the License for the specific language governing permissions and
013    // limitations under the License.
014    
015    package org.apache.tapestry5.ioc.internal;
016    
017    import org.apache.tapestry5.ioc.ObjectCreator;
018    import org.apache.tapestry5.ioc.ServiceBuilderResources;
019    import org.apache.tapestry5.ioc.internal.util.InternalUtils;
020    
021    import java.lang.reflect.Method;
022    
023    /**
024     * Basic implementation of {@link org.apache.tapestry5.ioc.ObjectCreator} that handles invoking a method on the module
025     * builder, and figures out the correct parameters to pass into the annotated method.
026     */
027    public class ServiceBuilderMethodInvoker extends AbstractServiceCreator
028    {
029        private final Method builderMethod;
030    
031        public ServiceBuilderMethodInvoker(ServiceBuilderResources resources, String creatorDescription, Method method)
032        {
033            super(resources, creatorDescription);
034    
035            builderMethod = method;
036        }
037    
038        private ObjectCreator<Object> plan;
039    
040        private ObjectCreator<Object> getPlan()
041        {
042            if (plan == null)
043            {
044                // Defer getting (and possibly instantiating) the module instance until the last possible
045                // moment. If the method is static, there's no need to even get the builder.
046    
047                final Object moduleInstance = InternalUtils.isStatic(builderMethod) ? null : resources.getModuleBuilder();
048    
049                plan = InternalUtils.createMethodInvocationPlan(resources.getTracker(), resources, createInjectionResources(), logger, "Constructing service implementation via " + creatorDescription, moduleInstance, builderMethod);
050            }
051    
052            return plan;
053        }
054    
055        /**
056         * Invoked from the proxy to create the actual service implementation.
057         */
058        public Object createObject()
059        {
060            Object result = getPlan().createObject();
061    
062            if (result == null)
063            {
064                throw new RuntimeException(String.format("Builder method %s (for service '%s') returned null.", creatorDescription, serviceId));
065            }
066    
067            return result;
068        }
069    
070        @Override
071        public String toString()
072        {
073            return creatorDescription;
074        }
075    }