de.mpg.mpdl.inge.syndication.presentation.RestServlet.java Source code

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Here is the source code for de.mpg.mpdl.inge.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.mpdl.inge.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.mpdl.inge.syndication.Syndication;
import de.mpg.mpdl.inge.syndication.SyndicationException;
import de.mpg.mpdl.inge.syndication.Utils;
import de.mpg.mpdl.inge.syndication.feed.Feed;
import de.mpg.mpdl.inge.util.PropertyReader;

/**
 * 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();
    }

}