eionet.web.filter.ContentNegotiationFilter.java Source code

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Here is the source code for eionet.web.filter.ContentNegotiationFilter.java

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/*
 * The contents of this file are subject to the Mozilla Public
 * License Version 1.1 (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.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS
 * IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
 * implied. See the License for the specific language governing
 * rights and limitations under the License.
 *
 * The Original Code is Content Registry 3
 *
 * The Initial Owner of the Original Code is European Environment
 * Agency. Portions created by TripleDev or Zero Technologies are Copyright
 * (C) European Environment Agency.  All Rights Reserved.
 *
 * Contributor(s):
 *        Juhan Voolaid
 */

package eionet.web.filter;

import java.io.IOException;

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

import org.apache.log4j.Logger;
import org.springframework.util.StringUtils;

/**
 * Fitler that checks if the Accept header wants RDF content, the request will be forwarded to RDF output page.
 *
 * @author Juhan Voolaid
 */
public class ContentNegotiationFilter implements Filter {

    /** Logger. */
    private static final Logger LOGGER = Logger.getLogger(ContentNegotiationFilter.class);

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
    }

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
            throws IOException, ServletException {
        request.setCharacterEncoding("utf-8");

        HttpServletRequest httpRequest = (HttpServletRequest) request;
        HttpServletResponse httpResponse = (HttpServletResponse) response;
        String requestUrl = httpRequest.getRequestURL().toString();

        if (!StringUtils.endsWithIgnoreCase(requestUrl, "/rdf")) {
            if (isRdfXmlPreferred(httpRequest)) {
                String redirectUrl = requestUrl + "/rdf";
                httpResponse.sendRedirect(redirectUrl);
                return;
            }
        }

        chain.doFilter(request, response);
    }

    @Override
    public void destroy() {
    }

    /**
     * Returns true, if request wants RDF content.
     *
     * @param httpRequest
     * @return
     */
    private boolean isRdfXmlPreferred(HttpServletRequest httpRequest) {
        String acceptHeader = httpRequest.getHeader("Accept");
        return acceptHeader != null && acceptHeader.trim().toLowerCase().startsWith("application/rdf+xml");
    }
}