001/*
002 * Copyright 2002-2016 the original author or authors.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *     https://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017package org.springframework.web.servlet.support;
018
019import org.springframework.util.ObjectUtils;
020import org.springframework.web.context.WebApplicationContext;
021import org.springframework.web.context.support.AnnotationConfigWebApplicationContext;
022
023/**
024 * Base class for {@link org.springframework.web.WebApplicationInitializer}
025 * implementations that register a
026 * {@link org.springframework.web.servlet.DispatcherServlet DispatcherServlet}
027 * configured with annotated classes, e.g. Spring's
028 * {@link org.springframework.context.annotation.Configuration @Configuration} classes.
029 *
030 * <p>Concrete implementations are required to implement {@link #getRootConfigClasses()}
031 * and {@link #getServletConfigClasses()} as well as {@link #getServletMappings()}.
032 * Further template and customization methods are provided by
033 * {@link AbstractDispatcherServletInitializer}.
034 *
035 * <p>This is the preferred approach for applications that use Java-based
036 * Spring configuration.
037 *
038 * @author Arjen Poutsma
039 * @author Chris Beams
040 * @since 3.2
041 */
042public abstract class AbstractAnnotationConfigDispatcherServletInitializer
043                extends AbstractDispatcherServletInitializer {
044
045        /**
046         * {@inheritDoc}
047         * <p>This implementation creates an {@link AnnotationConfigWebApplicationContext},
048         * providing it the annotated classes returned by {@link #getRootConfigClasses()}.
049         * Returns {@code null} if {@link #getRootConfigClasses()} returns {@code null}.
050         */
051        @Override
052        protected WebApplicationContext createRootApplicationContext() {
053                Class<?>[] configClasses = getRootConfigClasses();
054                if (!ObjectUtils.isEmpty(configClasses)) {
055                        AnnotationConfigWebApplicationContext rootAppContext = new AnnotationConfigWebApplicationContext();
056                        rootAppContext.register(configClasses);
057                        return rootAppContext;
058                }
059                else {
060                        return null;
061                }
062        }
063
064        /**
065         * {@inheritDoc}
066         * <p>This implementation creates an {@link AnnotationConfigWebApplicationContext},
067         * providing it the annotated classes returned by {@link #getServletConfigClasses()}.
068         */
069        @Override
070        protected WebApplicationContext createServletApplicationContext() {
071                AnnotationConfigWebApplicationContext servletAppContext = new AnnotationConfigWebApplicationContext();
072                Class<?>[] configClasses = getServletConfigClasses();
073                if (!ObjectUtils.isEmpty(configClasses)) {
074                        servletAppContext.register(configClasses);
075                }
076                return servletAppContext;
077        }
078
079        /**
080         * Specify {@link org.springframework.context.annotation.Configuration @Configuration}
081         * and/or {@link org.springframework.stereotype.Component @Component} classes to be
082         * provided to the {@linkplain #createRootApplicationContext() root application context}.
083         * @return the configuration classes for the root application context, or {@code null}
084         * if creation and registration of a root context is not desired
085         */
086        protected abstract Class<?>[] getRootConfigClasses();
087
088        /**
089         * Specify {@link org.springframework.context.annotation.Configuration @Configuration}
090         * and/or {@link org.springframework.stereotype.Component @Component} classes to be
091         * provided to the {@linkplain #createServletApplicationContext() dispatcher servlet
092         * application context}.
093         * @return the configuration classes for the dispatcher servlet application context or
094         * {@code null} if all configuration is specified through root config classes.
095         */
096        protected abstract Class<?>[] getServletConfigClasses();
097
098}