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.lang.Nullable;
023import org.springframework.util.Assert;
024import org.springframework.web.context.WebApplicationContext;
025import org.springframework.web.util.WebUtils;
026
027/**
028 * Convenience methods to retrieve Spring's root {@link WebApplicationContext}
029 * for a given JSF {@link FacesContext}. This is useful for accessing a
030 * Spring application context from custom JSF-based code.
031 *
032 * <p>Analogous to Spring's WebApplicationContextUtils for the ServletContext.
033 *
034 * @author Juergen Hoeller
035 * @since 1.1
036 * @see org.springframework.web.context.ContextLoader
037 * @see org.springframework.web.context.support.WebApplicationContextUtils
038 */
039public abstract class FacesContextUtils {
040
041        /**
042         * Find the root {@link WebApplicationContext} for this web app, typically
043         * loaded via {@link org.springframework.web.context.ContextLoaderListener}.
044         * <p>Will rethrow an exception that happened on root context startup,
045         * to differentiate between a failed context startup and no context at all.
046         * @param fc the FacesContext to find the web application context for
047         * @return the root WebApplicationContext for this web app, or {@code null} if none
048         * @see org.springframework.web.context.WebApplicationContext#ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE
049         */
050        @Nullable
051        public static WebApplicationContext getWebApplicationContext(FacesContext fc) {
052                Assert.notNull(fc, "FacesContext must not be null");
053                Object attr = fc.getExternalContext().getApplicationMap().get(
054                                WebApplicationContext.ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE);
055                if (attr == null) {
056                        return null;
057                }
058                if (attr instanceof RuntimeException) {
059                        throw (RuntimeException) attr;
060                }
061                if (attr instanceof Error) {
062                        throw (Error) attr;
063                }
064                if (!(attr instanceof WebApplicationContext)) {
065                        throw new IllegalStateException("Root context attribute is not of type WebApplicationContext: " + attr);
066                }
067                return (WebApplicationContext) attr;
068        }
069
070        /**
071         * Find the root {@link WebApplicationContext} for this web app, typically
072         * loaded via {@link org.springframework.web.context.ContextLoaderListener}.
073         * <p>Will rethrow an exception that happened on root context startup,
074         * to differentiate between a failed context startup and no context at all.
075         * @param fc the FacesContext to find the web application context for
076         * @return the root WebApplicationContext for this web app
077         * @throws IllegalStateException if the root WebApplicationContext could not be found
078         * @see org.springframework.web.context.WebApplicationContext#ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE
079         */
080        public static WebApplicationContext getRequiredWebApplicationContext(FacesContext fc) throws IllegalStateException {
081                WebApplicationContext wac = getWebApplicationContext(fc);
082                if (wac == null) {
083                        throw new IllegalStateException("No WebApplicationContext found: no ContextLoaderListener registered?");
084                }
085                return wac;
086        }
087
088        /**
089         * Return the best available mutex for the given session:
090         * that is, an object to synchronize on for the given session.
091         * <p>Returns the session mutex attribute if available; usually,
092         * this means that the HttpSessionMutexListener needs to be defined
093         * in {@code web.xml}. Falls back to the Session reference itself
094         * if no mutex attribute found.
095         * <p>The session mutex is guaranteed to be the same object during
096         * the entire lifetime of the session, available under the key defined
097         * by the {@code SESSION_MUTEX_ATTRIBUTE} constant. It serves as a
098         * safe reference to synchronize on for locking on the current session.
099         * <p>In many cases, the Session reference itself is a safe mutex
100         * as well, since it will always be the same object reference for the
101         * same active logical session. However, this is not guaranteed across
102         * different servlet containers; the only 100% safe way is a session mutex.
103         * @param fc the FacesContext to find the session mutex for
104         * @return the mutex object (never {@code null})
105         * @see org.springframework.web.util.WebUtils#SESSION_MUTEX_ATTRIBUTE
106         * @see org.springframework.web.util.HttpSessionMutexListener
107         */
108        @Nullable
109        public static Object getSessionMutex(FacesContext fc) {
110                Assert.notNull(fc, "FacesContext must not be null");
111                ExternalContext ec = fc.getExternalContext();
112                Object mutex = ec.getSessionMap().get(WebUtils.SESSION_MUTEX_ATTRIBUTE);
113                if (mutex == null) {
114                        mutex = ec.getSession(true);
115                }
116                return mutex;
117        }
118
119}