Java tutorial
/* * #%L * ********************************************************************************************************************* * * NorthernWind - lightweight CMS * http://northernwind.tidalwave.it - git clone https://bitbucket.org/tidalwave/northernwind-src.git * %% * Copyright (C) 2011 - 2016 Tidalwave s.a.s. (http://tidalwave.it) * %% * ********************************************************************************************************************* * * Licensed 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. * * ********************************************************************************************************************* * * $Id$ * * ********************************************************************************************************************* * #L% */ package it.tidalwave.northernwind.frontend.impl.ui; import javax.annotation.Nonnull; import javax.inject.Inject; import java.lang.reflect.InvocationTargetException; import java.lang.reflect.Constructor; import java.util.ArrayList; import java.util.List; import org.springframework.beans.factory.BeanCreationException; import org.springframework.beans.factory.BeanFactory; import org.springframework.beans.factory.annotation.Configurable; import it.tidalwave.util.Id; import it.tidalwave.util.NotFoundException; import it.tidalwave.northernwind.core.model.HttpStatusException; import it.tidalwave.northernwind.core.model.Site; import it.tidalwave.northernwind.core.model.SiteNode; import it.tidalwave.northernwind.core.model.SiteProvider; import it.tidalwave.northernwind.frontend.ui.ViewFactory.ViewAndController; import lombok.ToString; import lombok.extern.slf4j.Slf4j; /*********************************************************************************************************************** * * A builder which creates a View - ViewController pair. * * @stereotype Factory * * @author Fabrizio Giudici * @version $Id$ * **********************************************************************************************************************/ @Configurable @Slf4j @ToString(exclude = "beanFactory") /* package */ class ViewBuilder { @Inject private BeanFactory beanFactory; @Nonnull /* package */ final Constructor<?> viewConstructor; @Nonnull /* package */ final Constructor<?> viewControllerConstructor; /******************************************************************************************************************* * * ******************************************************************************************************************/ public ViewBuilder(final @Nonnull Class<?> viewClass, final @Nonnull Class<?> viewControllerClass) throws NoSuchMethodException, InvocationTargetException, InstantiationException, IllegalArgumentException, IllegalAccessException, SecurityException { viewConstructor = viewClass.getConstructors()[0]; viewControllerConstructor = viewControllerClass.getConstructors()[0]; } /******************************************************************************************************************* * * Creates a new View - ViewController pair. They are first instantiated, and then dependency injection by means * of constructor parameters occur. Injected fields are: the id, the {@link SiteNode}, any service declared in * the Spring context, including {@link Site}; furthermore, a reference of the View is injected in the Controller. * * @param id the view id * @param siteNode the {@link SiteNode} the view will be built for * @return the created view * ******************************************************************************************************************/ @Nonnull public ViewAndController createViewAndController(final @Nonnull Id id, final @Nonnull SiteNode siteNode) throws HttpStatusException { log.debug("createViewAndController({}, {})", id, siteNode); try { final Object view = viewConstructor .newInstance(computeConstructorArguments(viewConstructor, id, siteNode)); final Object controller = viewControllerConstructor .newInstance(computeConstructorArguments(viewControllerConstructor, id, siteNode, view)); return new ViewAndController(view, controller); } catch (InvocationTargetException e) { if (e.getCause() instanceof BeanCreationException) // FIXME: cumbersome { if (e.getCause().getCause() instanceof HttpStatusException) { throw (HttpStatusException) e.getCause().getCause(); } } throw new RuntimeException(e); } catch (Exception e) { throw new RuntimeException(e); } } /******************************************************************************************************************* * * Computes the argument values for calling the given constructor. They are taken from the current * {@link BeanFactory}, with {@code instanceArgs} eventually overriding them. * * @param constructor the constructor * @param overridingArgs the overriding arguments * @return the arguments to pass to the constructor * ******************************************************************************************************************/ @Nonnull private Object[] computeConstructorArguments(final @Nonnull Constructor<?> constructor, final @Nonnull Object... overridingArgs) throws NotFoundException { final List<Object> result = new ArrayList<>(); x: for (final Class<?> argumentType : constructor.getParameterTypes()) { for (final Object overridingArg : overridingArgs) { if (argumentType.isAssignableFrom(overridingArg.getClass())) { result.add(overridingArg); continue x; } } if (Site.class.isAssignableFrom(argumentType)) { result.add(beanFactory.getBean(SiteProvider.class).getSite()); } else { result.add(beanFactory.getBean(argumentType)); } } return result.toArray(); } }