org.ambraproject.web.VirtualJournalMappingFilter.java Source code

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Here is the source code for org.ambraproject.web.VirtualJournalMappingFilter.java

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/* $HeadURL::                                                                            $
 * $Id$
 *
 * Copyright (c) 2006-2010 by Public Library of Science
 * http://plos.org
 * http://ambraproject.org
 *
 * 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 org.ambraproject.web;

import java.io.IOException;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.apache.commons.configuration.Configuration;
import org.ambraproject.configuration.ConfigurationStore;

/**
 * A Filter that maps incoming URI Requests to an appropriate virtual journal resources. If a
 * virtual journal context is set, a lookup is done to see if an override for the requested
 * resource exists for the virtual journal.  If so, the Request is wrapped with the override
 * values and passed on to the FilterChain.  If not, the Request is wrapped with default values
 * for the resource and then passed to the FilterChain.
 */
public class VirtualJournalMappingFilter implements Filter {
    private static final Logger log = LoggerFactory.getLogger(VirtualJournalMappingFilter.class);
    private ServletContext servletContext = null;
    private Configuration configuration = null;

    /*
     * @see javax.servlet.Filter#init
     */
    public void init(final FilterConfig filterConfig) throws ServletException {
        // need ServletContext to get "real" path/file names
        this.servletContext = filterConfig.getServletContext();
        this.configuration = ConfigurationStore.getInstance().getConfiguration();
    }

    /*
     * @see javax.servlet.Filter#destroy
     */
    public void destroy() {

    }

    /*
     * @see javax.servlet.Filter#doFilter
     */
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain filterChain)
            throws ServletException, IOException {
        if (request instanceof HttpServletRequest) {
            HttpServletRequest r = (HttpServletRequest) request;
            HttpServletRequest mapped = mapRequest(r);

            if (log.isDebugEnabled()) {
                if (mapped == r)
                    log.debug("Passed thru unchanged " + r.getRequestURI());
                else
                    log.debug("Mapped " + r.getRequestURI() + " to " + mapped.getRequestURI());
            }

            request = mapped;
        }

        filterChain.doFilter(request, response);
    }

    /**
     * Map the request to a resource in the journal context.. If resource exists within the
     * virtual journal context, return a WrappedRequest with the mappingPrefix,  else return a
     * WrappedRequest for the default resource.
     *
     * @param request <code>HttpServletRequest</code> to apply the lookup against.
     *
     * @return WrappedRequest for the resource.
     *
     * @throws ServletException on an error
     */
    HttpServletRequest mapRequest(HttpServletRequest request) throws ServletException {
        VirtualJournalContext context = (VirtualJournalContext) request
                .getAttribute(VirtualJournalContext.PUB_VIRTUALJOURNAL_CONTEXT);
        if (context == null)
            return request;
        return context.mapRequest(request, configuration, servletContext);
    }
}