001/*
002 * Copyright 2002-2015 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.context.support;
018
019import java.io.File;
020import javax.servlet.ServletContext;
021
022import org.springframework.context.ApplicationContext;
023import org.springframework.context.support.ApplicationObjectSupport;
024import org.springframework.web.context.ServletContextAware;
025import org.springframework.web.context.WebApplicationContext;
026import org.springframework.web.util.WebUtils;
027
028/**
029 * Convenient superclass for application objects running in a {@link WebApplicationContext}.
030 * Provides {@code getWebApplicationContext()}, {@code getServletContext()}, and
031 * {@code getTempDir()} accessors.
032 *
033 * <p>Note: It is generally recommended to use individual callback interfaces for the actual
034 * callbacks needed. This broad base class is primarily intended for use within the framework,
035 * in case of {@link ServletContext} access etc typically being needed.
036 *
037 * @author Juergen Hoeller
038 * @since 28.08.2003
039 * @see SpringBeanAutowiringSupport
040 */
041public abstract class WebApplicationObjectSupport extends ApplicationObjectSupport implements ServletContextAware {
042
043        private ServletContext servletContext;
044
045
046        @Override
047        public final void setServletContext(ServletContext servletContext) {
048                if (servletContext != this.servletContext) {
049                        this.servletContext = servletContext;
050                        if (servletContext != null) {
051                                initServletContext(servletContext);
052                        }
053                }
054        }
055
056        /**
057         * Overrides the base class behavior to enforce running in an ApplicationContext.
058         * All accessors will throw IllegalStateException if not running in a context.
059         * @see #getApplicationContext()
060         * @see #getMessageSourceAccessor()
061         * @see #getWebApplicationContext()
062         * @see #getServletContext()
063         * @see #getTempDir()
064         */
065        @Override
066        protected boolean isContextRequired() {
067                return true;
068        }
069
070        /**
071         * Calls {@link #initServletContext(javax.servlet.ServletContext)} if the
072         * given ApplicationContext is a {@link WebApplicationContext}.
073         */
074        @Override
075        protected void initApplicationContext(ApplicationContext context) {
076                super.initApplicationContext(context);
077                if (this.servletContext == null && context instanceof WebApplicationContext) {
078                        this.servletContext = ((WebApplicationContext) context).getServletContext();
079                        if (this.servletContext != null) {
080                                initServletContext(this.servletContext);
081                        }
082                }
083        }
084
085        /**
086         * Subclasses may override this for custom initialization based
087         * on the ServletContext that this application object runs in.
088         * <p>The default implementation is empty. Called by
089         * {@link #initApplicationContext(org.springframework.context.ApplicationContext)}
090         * as well as {@link #setServletContext(javax.servlet.ServletContext)}.
091         * @param servletContext the ServletContext that this application object runs in
092         * (never {@code null})
093         */
094        protected void initServletContext(ServletContext servletContext) {
095        }
096
097        /**
098         * Return the current application context as WebApplicationContext.
099         * <p><b>NOTE:</b> Only use this if you actually need to access
100         * WebApplicationContext-specific functionality. Preferably use
101         * {@code getApplicationContext()} or {@code getServletContext()}
102         * else, to be able to run in non-WebApplicationContext environments as well.
103         * @throws IllegalStateException if not running in a WebApplicationContext
104         * @see #getApplicationContext()
105         */
106        protected final WebApplicationContext getWebApplicationContext() throws IllegalStateException {
107                ApplicationContext ctx = getApplicationContext();
108                if (ctx instanceof WebApplicationContext) {
109                        return (WebApplicationContext) getApplicationContext();
110                }
111                else if (isContextRequired()) {
112                        throw new IllegalStateException("WebApplicationObjectSupport instance [" + this +
113                                        "] does not run in a WebApplicationContext but in: " + ctx);
114                }
115                else {
116                        return null;
117                }
118        }
119
120        /**
121         * Return the current ServletContext.
122         * @throws IllegalStateException if not running within a ServletContext
123         */
124        protected final ServletContext getServletContext() throws IllegalStateException {
125                if (this.servletContext != null) {
126                        return this.servletContext;
127                }
128                WebApplicationContext wac = getWebApplicationContext();
129                if (wac == null) {
130                        return null;
131                }
132                ServletContext servletContext = wac.getServletContext();
133                if (servletContext == null && isContextRequired()) {
134                        throw new IllegalStateException("WebApplicationObjectSupport instance [" + this +
135                                        "] does not run within a ServletContext. Make sure the object is fully configured!");
136                }
137                return servletContext;
138        }
139
140        /**
141         * Return the temporary directory for the current web application,
142         * as provided by the servlet container.
143         * @return the File representing the temporary directory
144         * @throws IllegalStateException if not running within a ServletContext
145         * @see org.springframework.web.util.WebUtils#getTempDir(javax.servlet.ServletContext)
146         */
147        protected final File getTempDir() throws IllegalStateException {
148                return WebUtils.getTempDir(getServletContext());
149        }
150
151}