Java tutorial
/** * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You 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. */ package org.apache.isis.core.metamodel.services.grid; import java.io.IOException; import java.net.URL; import java.nio.charset.Charset; import java.util.List; import java.util.Map; import java.util.Objects; import javax.annotation.PostConstruct; import javax.inject.Inject; import javax.xml.bind.JAXBContext; import com.google.common.base.Function; import com.google.common.collect.FluentIterable; import com.google.common.collect.Maps; import com.google.common.io.Resources; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.apache.isis.applib.DomainObjectContainer; import org.apache.isis.applib.annotation.DomainService; import org.apache.isis.applib.annotation.NatureOfService; import org.apache.isis.applib.annotation.Programmatic; import org.apache.isis.applib.layout.component.Grid; import org.apache.isis.applib.services.grid.GridLoaderService; import org.apache.isis.applib.services.grid.GridSystemService; import org.apache.isis.applib.services.jaxb.JaxbService; import org.apache.isis.core.metamodel.deployment.DeploymentCategoryProvider; @DomainService(nature = NatureOfService.DOMAIN) public class GridLoaderServiceDefault implements GridLoaderService { private static final Logger LOG = LoggerFactory.getLogger(GridLoaderServiceDefault.class); // for better logging messages (used only in prototyping mode) private final Map<Class<?>, String> badXmlByClass = Maps.newHashMap(); // cache (used only in prototyping mode) private final Map<String, Grid> gridByXml = Maps.newHashMap(); private List<Class<? extends Grid>> pageImplementations; @PostConstruct public void init() { pageImplementations = FluentIterable.from(gridSystemServices) .transform(new Function<GridSystemService, Class<? extends Grid>>() { @Override public Class<? extends Grid> apply(final GridSystemService gridSystemService) { return gridSystemService.gridImplementation(); } }).toList(); } @Override public boolean supportsReloading() { return !deploymentCategoryProvider.getDeploymentCategory().isProduction(); } @Override public void remove(final Class<?> domainClass) { if (!supportsReloading()) { return; } badXmlByClass.remove(domainClass); final String xml = loadXml(domainClass); if (xml == null) { return; } gridByXml.remove(xml); } @Override @Programmatic public boolean existsFor(final Class<?> domainClass) { final URL resource = Resources.getResource(domainClass, resourceNameFor(domainClass)); return resource != null; } @Override @Programmatic public Grid load(final Class<?> domainClass) { final String xml = loadXml(domainClass); if (xml == null) { return null; } if (supportsReloading()) { final Grid grid = gridByXml.get(xml); if (grid != null) { return grid; } final String badXml = badXmlByClass.get(domainClass); if (badXml != null) { if (Objects.equals(xml, badXml)) { // seen this before and already logged; just quit return null; } else { // this different XML might be good badXmlByClass.remove(domainClass); } } } try { // all known implementations of Page final JAXBContext context = JAXBContext.newInstance(pageImplementations.toArray(new Class[0])); final Grid grid = (Grid) jaxbService.fromXml(context, xml); grid.setDomainClass(domainClass); if (supportsReloading()) { gridByXml.put(xml, grid); } return grid; } catch (Exception ex) { if (supportsReloading()) { // save fact that this was bad XML, so that we don't log again if called next time badXmlByClass.put(domainClass, xml); } // note that we don't blacklist if the file exists but couldn't be parsed; // the developer might fix so we will want to retry. final String resourceName = resourceNameFor(domainClass); final String message = "Failed to parse " + resourceName + " file (" + ex.getMessage() + ")"; if (supportsReloading()) { container.warnUser(message); } LOG.warn(message); return null; } } private String loadXml(final Class<?> domainClass) { final String resourceName = resourceNameFor(domainClass); try { return resourceContentOf(domainClass, resourceName); } catch (IOException | IllegalArgumentException ex) { if (LOG.isDebugEnabled()) { final String message = String.format("Failed to locate file %s (relative to %s.class); ex: %s)", resourceName, domainClass.getName(), ex.getMessage()); LOG.debug(message); } return null; } } private static String resourceContentOf(final Class<?> cls, final String resourceName) throws IOException { final URL url = Resources.getResource(cls, resourceName); return Resources.toString(url, Charset.defaultCharset()); } private String resourceNameFor(final Class<?> domainClass) { return domainClass.getSimpleName() + ".layout.xml"; } //region > injected dependencies @javax.inject.Inject DeploymentCategoryProvider deploymentCategoryProvider; @javax.inject.Inject DomainObjectContainer container; @javax.inject.Inject JaxbService jaxbService; @javax.inject.Inject List<GridSystemService> gridSystemServices; //endregion }