facescontextfilter.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 java.io.IOException;

import javax.faces.context.FacesContext;
import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;

import org.springframework.web.filter.GenericFilterBean;

/**
 * <strong>{@link javax.servlet.Filter}</strong> implementation that creates
 * and releases a {@link FacesContext} which contains per-request state
 * information. Should be used if it is necessary to implement
 * {@link javax.servlet.Filter}s which want to access the current FacesContext.
 * <em>This class should be the first Filter in the filter chain.</em>
 * 
 * @author Andreas Kuhrwahl
 * 
 */
public final class FacesContextFilter extends GenericFilterBean {

    /** For creating and releasing the {@link FacesContext}. */
    private final FacesContextLoader facesContextProvider = FacesContextLoader
            .getCurrentInstance();

    /**
     * {@inheritDoc}
     */
    public void doFilter(final ServletRequest request,
            final ServletResponse response, final FilterChain chain)
            throws IOException, ServletException {
        FacesContext facesContext = this.facesContextProvider.initFacesContext(
                getFilterConfig().getServletContext(), request, response);
        try {
            chain.doFilter(request, response);
        } finally {
            this.facesContextProvider.releaseFacesContext(facesContext);
        }
    }

}