Java tutorial
/* * Copyright 2002-2018 the original author or authors. * * 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 * * https://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.springframework.web.servlet.config.annotation; import java.util.ArrayList; import java.util.Arrays; import java.util.Collections; import java.util.List; import org.springframework.beans.factory.BeanFactoryUtils; import org.springframework.beans.factory.BeanInitializationException; import org.springframework.context.ApplicationContext; import org.springframework.core.Ordered; import org.springframework.lang.Nullable; import org.springframework.util.CollectionUtils; import org.springframework.util.ObjectUtils; import org.springframework.web.accept.ContentNegotiationManager; import org.springframework.web.servlet.View; import org.springframework.web.servlet.ViewResolver; import org.springframework.web.servlet.view.BeanNameViewResolver; import org.springframework.web.servlet.view.ContentNegotiatingViewResolver; import org.springframework.web.servlet.view.InternalResourceViewResolver; import org.springframework.web.servlet.view.freemarker.FreeMarkerConfigurer; import org.springframework.web.servlet.view.freemarker.FreeMarkerViewResolver; import org.springframework.web.servlet.view.groovy.GroovyMarkupConfigurer; import org.springframework.web.servlet.view.groovy.GroovyMarkupViewResolver; import org.springframework.web.servlet.view.script.ScriptTemplateConfigurer; import org.springframework.web.servlet.view.script.ScriptTemplateViewResolver; import org.springframework.web.servlet.view.tiles3.TilesConfigurer; import org.springframework.web.servlet.view.tiles3.TilesViewResolver; /** * Assist with the configuration of a chain of * {@link org.springframework.web.servlet.ViewResolver ViewResolver} instances. * This class is expected to be used via {@link WebMvcConfigurer#configureViewResolvers}. * * @author Sebastien Deleuze * @author Rossen Stoyanchev * @since 4.1 */ public class ViewResolverRegistry { @Nullable private ContentNegotiationManager contentNegotiationManager; @Nullable private ApplicationContext applicationContext; @Nullable private ContentNegotiatingViewResolver contentNegotiatingResolver; private final List<ViewResolver> viewResolvers = new ArrayList<>(4); @Nullable private Integer order; /** * Class constructor with {@link ContentNegotiationManager} and {@link ApplicationContext}. * @since 4.3.12 */ public ViewResolverRegistry(ContentNegotiationManager contentNegotiationManager, @Nullable ApplicationContext context) { this.contentNegotiationManager = contentNegotiationManager; this.applicationContext = context; } /** * Whether any view resolvers have been registered. */ public boolean hasRegistrations() { return (this.contentNegotiatingResolver != null || !this.viewResolvers.isEmpty()); } /** * Enable use of a {@link ContentNegotiatingViewResolver} to front all other * configured view resolvers and select among all selected Views based on * media types requested by the client (e.g. in the Accept header). * <p>If invoked multiple times the provided default views will be added to * any other default views that may have been configured already. * @see ContentNegotiatingViewResolver#setDefaultViews */ public void enableContentNegotiation(View... defaultViews) { initContentNegotiatingViewResolver(defaultViews); } /** * Enable use of a {@link ContentNegotiatingViewResolver} to front all other * configured view resolvers and select among all selected Views based on * media types requested by the client (e.g. in the Accept header). * <p>If invoked multiple times the provided default views will be added to * any other default views that may have been configured already. * @see ContentNegotiatingViewResolver#setDefaultViews */ public void enableContentNegotiation(boolean useNotAcceptableStatus, View... defaultViews) { ContentNegotiatingViewResolver vr = initContentNegotiatingViewResolver(defaultViews); vr.setUseNotAcceptableStatusCode(useNotAcceptableStatus); } private ContentNegotiatingViewResolver initContentNegotiatingViewResolver(View[] defaultViews) { // ContentNegotiatingResolver in the registry: elevate its precedence! this.order = (this.order != null ? this.order : Ordered.HIGHEST_PRECEDENCE); if (this.contentNegotiatingResolver != null) { if (!ObjectUtils.isEmpty(defaultViews) && !CollectionUtils.isEmpty(this.contentNegotiatingResolver.getDefaultViews())) { List<View> views = new ArrayList<>(this.contentNegotiatingResolver.getDefaultViews()); views.addAll(Arrays.asList(defaultViews)); this.contentNegotiatingResolver.setDefaultViews(views); } } else { this.contentNegotiatingResolver = new ContentNegotiatingViewResolver(); this.contentNegotiatingResolver.setDefaultViews(Arrays.asList(defaultViews)); this.contentNegotiatingResolver.setViewResolvers(this.viewResolvers); if (this.contentNegotiationManager != null) { this.contentNegotiatingResolver.setContentNegotiationManager(this.contentNegotiationManager); } } return this.contentNegotiatingResolver; } /** * Register JSP view resolver using a default view name prefix of "/WEB-INF/" * and a default suffix of ".jsp". * <p>When this method is invoked more than once, each call will register a * new ViewResolver instance. Note that since it's not easy to determine * if a JSP exists without forwarding to it, using multiple JSP-based view * resolvers only makes sense in combination with the "viewNames" property * on the resolver indicating which view names are handled by which resolver. */ public UrlBasedViewResolverRegistration jsp() { return jsp("/WEB-INF/", ".jsp"); } /** * Register JSP view resolver with the specified prefix and suffix. * <p>When this method is invoked more than once, each call will register a * new ViewResolver instance. Note that since it's not easy to determine * if a JSP exists without forwarding to it, using multiple JSP-based view * resolvers only makes sense in combination with the "viewNames" property * on the resolver indicating which view names are handled by which resolver. */ public UrlBasedViewResolverRegistration jsp(String prefix, String suffix) { InternalResourceViewResolver resolver = new InternalResourceViewResolver(); resolver.setPrefix(prefix); resolver.setSuffix(suffix); this.viewResolvers.add(resolver); return new UrlBasedViewResolverRegistration(resolver); } /** * Register Tiles 3.x view resolver. * <p><strong>Note</strong> that you must also configure Tiles by adding a * {@link org.springframework.web.servlet.view.tiles3.TilesConfigurer} bean. */ public UrlBasedViewResolverRegistration tiles() { if (!checkBeanOfType(TilesConfigurer.class)) { throw new BeanInitializationException("In addition to a Tiles view resolver " + "there must also be a single TilesConfigurer bean in this web application context " + "(or its parent)."); } TilesRegistration registration = new TilesRegistration(); this.viewResolvers.add(registration.getViewResolver()); return registration; } /** * Register a FreeMarker view resolver with an empty default view name * prefix and a default suffix of ".ftl". * <p><strong>Note</strong> that you must also configure FreeMarker by adding a * {@link org.springframework.web.servlet.view.freemarker.FreeMarkerConfigurer} bean. */ public UrlBasedViewResolverRegistration freeMarker() { if (!checkBeanOfType(FreeMarkerConfigurer.class)) { throw new BeanInitializationException("In addition to a FreeMarker view resolver " + "there must also be a single FreeMarkerConfig bean in this web application context " + "(or its parent): FreeMarkerConfigurer is the usual implementation. " + "This bean may be given any name."); } FreeMarkerRegistration registration = new FreeMarkerRegistration(); this.viewResolvers.add(registration.getViewResolver()); return registration; } /** * Register a Groovy markup view resolver with an empty default view name * prefix and a default suffix of ".tpl". */ public UrlBasedViewResolverRegistration groovy() { if (!checkBeanOfType(GroovyMarkupConfigurer.class)) { throw new BeanInitializationException("In addition to a Groovy markup view resolver " + "there must also be a single GroovyMarkupConfig bean in this web application context " + "(or its parent): GroovyMarkupConfigurer is the usual implementation. " + "This bean may be given any name."); } GroovyMarkupRegistration registration = new GroovyMarkupRegistration(); this.viewResolvers.add(registration.getViewResolver()); return registration; } /** * Register a script template view resolver with an empty default view name prefix and suffix. * @since 4.2 */ public UrlBasedViewResolverRegistration scriptTemplate() { if (!checkBeanOfType(ScriptTemplateConfigurer.class)) { throw new BeanInitializationException("In addition to a script template view resolver " + "there must also be a single ScriptTemplateConfig bean in this web application context " + "(or its parent): ScriptTemplateConfigurer is the usual implementation. " + "This bean may be given any name."); } ScriptRegistration registration = new ScriptRegistration(); this.viewResolvers.add(registration.getViewResolver()); return registration; } /** * Register a bean name view resolver that interprets view names as the names * of {@link org.springframework.web.servlet.View} beans. */ public void beanName() { BeanNameViewResolver resolver = new BeanNameViewResolver(); this.viewResolvers.add(resolver); } /** * Register a {@link ViewResolver} bean instance. This may be useful to * configure a custom (or 3rd party) resolver implementation. It may also be * used as an alternative to other registration methods in this class when * they don't expose some more advanced property that needs to be set. */ public void viewResolver(ViewResolver viewResolver) { if (viewResolver instanceof ContentNegotiatingViewResolver) { throw new BeanInitializationException( "addViewResolver cannot be used to configure a ContentNegotiatingViewResolver. " + "Please use the method enableContentNegotiation instead."); } this.viewResolvers.add(viewResolver); } /** * ViewResolver's registered through this registry are encapsulated in an * instance of {@link org.springframework.web.servlet.view.ViewResolverComposite * ViewResolverComposite} and follow the order of registration. * This property determines the order of the ViewResolverComposite itself * relative to any additional ViewResolver's (not registered here) present in * the Spring configuration * <p>By default this property is not set, which means the resolver is ordered * at {@link Ordered#LOWEST_PRECEDENCE} unless content negotiation is enabled * in which case the order (if not set explicitly) is changed to * {@link Ordered#HIGHEST_PRECEDENCE}. */ public void order(int order) { this.order = order; } private boolean checkBeanOfType(Class<?> beanType) { return (this.applicationContext == null || !ObjectUtils.isEmpty(BeanFactoryUtils .beanNamesForTypeIncludingAncestors(this.applicationContext, beanType, false, false))); } protected int getOrder() { return (this.order != null ? this.order : Ordered.LOWEST_PRECEDENCE); } protected List<ViewResolver> getViewResolvers() { if (this.contentNegotiatingResolver != null) { return Collections.<ViewResolver>singletonList(this.contentNegotiatingResolver); } else { return this.viewResolvers; } } private static class TilesRegistration extends UrlBasedViewResolverRegistration { public TilesRegistration() { super(new TilesViewResolver()); } } private static class FreeMarkerRegistration extends UrlBasedViewResolverRegistration { public FreeMarkerRegistration() { super(new FreeMarkerViewResolver()); getViewResolver().setSuffix(".ftl"); } } private static class GroovyMarkupRegistration extends UrlBasedViewResolverRegistration { public GroovyMarkupRegistration() { super(new GroovyMarkupViewResolver()); getViewResolver().setSuffix(".tpl"); } } private static class ScriptRegistration extends UrlBasedViewResolverRegistration { public ScriptRegistration() { super(new ScriptTemplateViewResolver()); getViewResolver(); } } }