001/*
002 * Copyright 2002-2014 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.jsf;
018
019import javax.faces.context.ExternalContext;
020import javax.faces.context.FacesContext;
021
022import org.springframework.util.Assert;
023import org.springframework.web.context.WebApplicationContext;
024import org.springframework.web.util.WebUtils;
025
026/**
027 * Convenience methods to retrieve Spring's root {@link WebApplicationContext}
028 * for a given JSF {@link FacesContext}. This is useful for accessing a
029 * Spring application context from custom JSF-based code.
030 *
031 * <p>Analogous to Spring's WebApplicationContextUtils for the ServletContext.
032 *
033 * @author Juergen Hoeller
034 * @since 1.1
035 * @see org.springframework.web.context.ContextLoader
036 * @see org.springframework.web.context.support.WebApplicationContextUtils
037 */
038public abstract class FacesContextUtils {
039
040        /**
041         * Find the root {@link WebApplicationContext} for this web app, typically
042         * loaded via {@link org.springframework.web.context.ContextLoaderListener}.
043         * <p>Will rethrow an exception that happened on root context startup,
044         * to differentiate between a failed context startup and no context at all.
045         * @param fc the FacesContext to find the web application context for
046         * @return the root WebApplicationContext for this web app, or {@code null} if none
047         * @see org.springframework.web.context.WebApplicationContext#ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE
048         */
049        public static WebApplicationContext getWebApplicationContext(FacesContext fc) {
050                Assert.notNull(fc, "FacesContext must not be null");
051                Object attr = fc.getExternalContext().getApplicationMap().get(
052                                WebApplicationContext.ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE);
053                if (attr == null) {
054                        return null;
055                }
056                if (attr instanceof RuntimeException) {
057                        throw (RuntimeException) attr;
058                }
059                if (attr instanceof Error) {
060                        throw (Error) attr;
061                }
062                if (!(attr instanceof WebApplicationContext)) {
063                        throw new IllegalStateException("Root context attribute is not of type WebApplicationContext: " + attr);
064                }
065                return (WebApplicationContext) attr;
066        }
067
068        /**
069         * Find the root {@link WebApplicationContext} for this web app, typically
070         * loaded via {@link org.springframework.web.context.ContextLoaderListener}.
071         * <p>Will rethrow an exception that happened on root context startup,
072         * to differentiate between a failed context startup and no context at all.
073         * @param fc the FacesContext to find the web application context for
074         * @return the root WebApplicationContext for this web app
075         * @throws IllegalStateException if the root WebApplicationContext could not be found
076         * @see org.springframework.web.context.WebApplicationContext#ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE
077         */
078        public static WebApplicationContext getRequiredWebApplicationContext(FacesContext fc) throws IllegalStateException {
079                WebApplicationContext wac = getWebApplicationContext(fc);
080                if (wac == null) {
081                        throw new IllegalStateException("No WebApplicationContext found: no ContextLoaderListener registered?");
082                }
083                return wac;
084        }
085
086        /**
087         * Return the best available mutex for the given session:
088         * that is, an object to synchronize on for the given session.
089         * <p>Returns the session mutex attribute if available; usually,
090         * this means that the HttpSessionMutexListener needs to be defined
091         * in {@code web.xml}. Falls back to the Session reference itself
092         * if no mutex attribute found.
093         * <p>The session mutex is guaranteed to be the same object during
094         * the entire lifetime of the session, available under the key defined
095         * by the {@code SESSION_MUTEX_ATTRIBUTE} constant. It serves as a
096         * safe reference to synchronize on for locking on the current session.
097         * <p>In many cases, the Session reference itself is a safe mutex
098         * as well, since it will always be the same object reference for the
099         * same active logical session. However, this is not guaranteed across
100         * different servlet containers; the only 100% safe way is a session mutex.
101         * @param fc the FacesContext to find the session mutex for
102         * @return the mutex object (never {@code null})
103         * @see org.springframework.web.util.WebUtils#SESSION_MUTEX_ATTRIBUTE
104         * @see org.springframework.web.util.HttpSessionMutexListener
105         */
106        public static Object getSessionMutex(FacesContext fc) {
107                Assert.notNull(fc, "FacesContext must not be null");
108                ExternalContext ec = fc.getExternalContext();
109                Object mutex = ec.getSessionMap().get(WebUtils.SESSION_MUTEX_ATTRIBUTE);
110                if (mutex == null) {
111                        mutex = ec.getSession(true);
112                }
113                return mutex;
114        }
115
116}