    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}