facescontextloader.java

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/*
 * Copyright 2002-2004 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
 * 
 *      http://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 de.mindmatters.faces.spring.context.servlet;

import javax.faces.FacesException;
import javax.faces.FactoryFinder;
import javax.faces.context.FacesContext;
import javax.faces.context.FacesContextFactory;
import javax.faces.lifecycle.Lifecycle;
import javax.faces.lifecycle.LifecycleFactory;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;

import de.mindmatters.faces.lifecycle.LifecycleImpl;

/**
 * Performs the actual initialization work for a {@link FacesContext} which
 * contains all of the per-request state information. Called by
 * {@link FacesContextFilter} and {@link FacesDispatcherServlet}.
 * 
 * @author Andreas Kuhrwahl
 * @see FacesContextFilter
 * @see FacesDispatcherServlet
 */
public final class FacesContextLoader {

    /** The Singleton instance of the FacesContextLoader. */
    private static final FacesContextLoader INSTANCE = new FacesContextLoader();

    /** The JSF-Spring Lifecycle needed for FacesContext creation. */
    private final Lifecycle lifecycle = ((LifecycleFactory) FactoryFinder
            .getFactory(FactoryFinder.LIFECYCLE_FACTORY))
            .getLifecycle(LifecycleImpl.JSF_SPRING_LIFECYCLE_ID);

    /** The {@link FacesContextFactory} for FacesContext creation. */
    private final FacesContextFactory facesContextFactory = (FacesContextFactory) FactoryFinder
            .getFactory(FactoryFinder.FACES_CONTEXT_FACTORY);

    /**
     * Constructor.
     */
    private FacesContextLoader() {
        super();
    }

    /**
     * @return The singleton instance of FacesContextLoader.
     */
    public static FacesContextLoader getCurrentInstance() {
        return INSTANCE;
    }

    /**
     * Create (if needed) and return a {@link FacesContext} instance that is
     * initialized for the processing of the specified request and response
     * objects.
     * 
     * @param servletContext
     *            the <code>ServletContext</code> that is associated with this
     *            web
     * @param request
     *            the <code>ServletRequest</code> that is to be processed
     * @param response
     *            the <code>ServletResponse</code> that is to be processed
     * @return The {@link FacesContext} instance
     * @throws ServletException
     *             if a {@link FacesContext} cannot be constructed for the
     *             specified parameters
     * @see FacesContextFactory#getFacesContext(Object, Object, Object,
     *      Lifecycle)
     */
    public FacesContext initFacesContext(final ServletContext servletContext,
            final ServletRequest request, final ServletResponse response)
            throws ServletException {
        try {
            return this.facesContextFactory.getFacesContext(servletContext,
                    request, response, this.lifecycle);
        } catch (FacesException ex) {
            throw new ServletException(ex);
        }
    }

    /**
     * Release any resources associated with the given <code>FacesContext</code>
     * instance.
     * 
     * @param context
     *            the FacesContext which contains per-request state information
     * @see FacesContext#release()
     */
    public void releaseFacesContext(final FacesContext context) {
        context.release();
    }

}