de.mpg.escidoc.services.syndication.presentation.RestServlet.java Source code

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Here is the source code for de.mpg.escidoc.services.syndication.presentation.RestServlet.java

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/*
 * CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License, Version 1.0 only
* (the "License"). You may not use this file except in compliance
* with the License.
*
* You can obtain a copy of the license at license/ESCIDOC.LICENSE
* or http://www.escidoc.org/license.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at license/ESCIDOC.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/

/*
* Copyright 2006-2012 Fachinformationszentrum Karlsruhe Gesellschaft
* fr wissenschaftlich-technische Information mbH and Max-Planck-
* Gesellschaft zur Frderung der Wissenschaft e.V.
* All rights reserved. Use is subject to license terms.
*/

package de.mpg.escidoc.services.syndication.presentation;

import java.io.BufferedInputStream;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.io.Writer;
import java.net.URISyntaxException;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.TimeZone;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.lang.StringUtils;
import org.apache.log4j.Logger;

import com.sun.syndication.io.FeedException;

import de.mpg.escidoc.services.framework.PropertyReader;
import de.mpg.escidoc.services.syndication.Syndication;
import de.mpg.escidoc.services.syndication.SyndicationException;
import de.mpg.escidoc.services.syndication.Utils;
import de.mpg.escidoc.services.syndication.feed.Feed;

/**
 * The servlet takes URL, calls eSciDoc syndication manager and 
 * returns generated RSS/ATOM  feed to the client.  
 *    
 * @author Vlad Makarenko  (initial creation) 
 * @author $Author$ (last modification)
 * $Revision$
 * $LastChangedDate$ 
 */

public class RestServlet extends HttpServlet {

    /** Serial identifier. */
    private static final long serialVersionUID = 1L;
    /** Logging instance. */
    private static final Logger logger = Logger.getLogger(RestServlet.class);

    /* Syndication Manager Instance  */
    Syndication synd;

    public RestServlet() throws IOException, SyndicationException {
        synd = new Syndication();
    }

    /**
     * {@inheritDoc}
     */
    @Override
    protected final void doGet(final HttpServletRequest req, final HttpServletResponse resp)
            throws ServletException, IOException {
        doPost(req, resp);
    }

    /**
     * {@inheritDoc}
     */
    @Override
    protected final void doPost(final HttpServletRequest req, final HttpServletResponse resp)
            throws ServletException, IOException {
        String url = null;
        try {
            url = PropertyReader.getProperty("escidoc.syndication.service.url") + req.getServletPath()
                    + req.getPathInfo();
        } catch (Exception e) {
            handleException(e, resp);
        }
        String q = req.getQueryString();

        if (Utils.checkVal(q)) {
            url += "?" + q;
        }

        Feed feed = synd.getFeeds().matchFeedByUri(url);

        //set correct mime-type
        resp.setContentType("application/" + (url.contains("rss_") ? "rss" : "atom") + "+xml; charset=utf-8");

        //cache handling
        String ttl = feed.getCachingTtl();

        if (Utils.checkVal(ttl)) {
            long ttlLong = Long.parseLong(ttl) * 1000L;
            resp.setHeader("control-cache", "max-age=" + ttl + ", must-revalidate");

            DateFormat df = new SimpleDateFormat("E, dd MMM yyyy HH:mm:ss z");
            df.setTimeZone(TimeZone.getTimeZone("GMT"));
            resp.setHeader("Expires", df.format(new Date(System.currentTimeMillis() + ttlLong)));
        }

        try {
            synd.getFeed(url, resp.getWriter());
        } catch (SyndicationException e) {
            handleException(e, resp);
        } catch (URISyntaxException e) {
            resp.sendError(HttpServletResponse.SC_BAD_REQUEST, "Wrong URI syntax: " + url);
            return;
        } catch (FeedException e) {
            handleException(e, resp);
        }

    }

    /**
     * Take care on an incoming exception.
     * 
     * @param e
     *            exception
     * @param resp
     *            response stream
     * @throws IOException 
     * @throws Exception
     *             if the handling went wrong on any reason
     */
    private void handleException(final Exception e, final HttpServletResponse resp) throws IOException {
        logger.error(e.getMessage(), e);

        PrintWriter pw;
        pw = resp.getWriter();
        pw.print("Error: ");
        e.printStackTrace(pw);
        pw.close();
    }

}