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
015package org.apache.tapestry5.ioc.internal;
016
017import org.apache.tapestry5.ioc.ObjectCreator;
018import org.apache.tapestry5.ioc.ServiceBuilderResources;
019import org.apache.tapestry5.ioc.internal.util.InternalUtils;
020
021import 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 */
027public 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    @Override
059    public Object createObject()
060    {
061        Object result = getPlan().createObject();
062
063        if (result == null)
064        {
065            throw new RuntimeException(String.format("Builder method %s (for service '%s') returned null.", creatorDescription, serviceId));
066        }
067
068        return result;
069    }
070
071    @Override
072    public String toString()
073    {
074        return creatorDescription;
075    }
076}