TransportProxyServlet.java

/*
 * Copyright (c) 2009, University of Bristol
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1) Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 *
 * 2) Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 *
 * 3) Neither the name of the University of Bristol nor the names of its
 *    contributors may be used to endorse or promote products derived from this
 *    software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 */
package org.ilrt.mca.servlet;

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import org.apache.log4j.Logger;
import org.ilrt.mca.domain.transport.DepartureInfo;
import org.ilrt.mca.domain.transport.DepartureService;
import org.ilrt.mca.domain.transport.DepartureUtils;

import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.InputStream;
import java.util.Properties;

/**
 * @author Jasper Tredgold (jasper.tredgold@bristol.ac.uk)
 */
public class TransportProxyServlet extends HttpServlet {

    public static final String TRANSPORT_SERVICE_KEY = "org.ilrt.mca.transport.class";

    private final Logger log = Logger.getLogger(TransportProxyServlet.class);

    private DepartureService departureService;

    @Override
    public void init(ServletConfig config) throws ServletException {

        log.info("TransportProxyServlet started.");

        super.init(config);

        // find the configuration files
        String configLocation = config.getInitParameter("config-file");

        Properties props = new Properties();
        try {
            InputStream in = getClass().getResourceAsStream(
                    configLocation);
            if (in == null) {
                throw new RuntimeException("Config file " + configLocation
                        + " not found in classpath");
            }
            props.load(in);

            String class_name = props.getProperty(TRANSPORT_SERVICE_KEY);
            if (class_name != null) {
                try {
                    Object instance = Class.forName(class_name).newInstance();
                    if (instance instanceof DepartureService) {
                        departureService = (DepartureService) instance;
                        departureService.init(props);
                    }
                } catch (ClassNotFoundException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                } catch (InstantiationException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                } catch (IllegalAccessException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
            }

        } catch (IOException e) {
            log.error("TransportProxyServlet. Failed to load properties. "
                    + e.getLocalizedMessage());
        }
    }

    @Override
    public void destroy() {
        log.info("TransportProxyServlet shutdown.");
    }

    @Override
    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws IOException {

        String dep_loc = request.getParameter("id");

        if (dep_loc == null || dep_loc.trim().length() == 0) {
            response.sendError(HttpServletResponse.SC_NOT_ACCEPTABLE); // TODO check correct response
            return;
        }

        try {

            DepartureInfo info = departureService.getDepartureInfo(dep_loc);

            // return json
            Gson gson = new GsonBuilder().excludeFieldsWithoutExposeAnnotation().create();

            response.setContentType("application/json");
            response.getWriter().print(gson.toJson(DepartureUtils.toMap(info)));

        } catch (Exception e) {
            response.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
        }
    }
}