edu.emory.library.tast.database.graphs.GraphsServlet.java Source code

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Here is the source code for edu.emory.library.tast.database.graphs.GraphsServlet.java

Source

/*
Copyright 2010 Emory University
       
   This file is part of Trans-Atlantic Slave Voyages.
       
   Trans-Atlantic Slave Voyages is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.
       
   Trans-Atlantic Slave Voyages is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
       
   You should have received a copy of the GNU General Public License
   along with Trans-Atlantic Slave Voyages.  If not, see <http://www.gnu.org/licenses/>. 
*/
package edu.emory.library.tast.database.graphs;

import java.io.IOException;
import java.io.OutputStream;

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

import org.jfree.chart.ChartUtilities;
import org.jfree.chart.JFreeChart;

/**
 * Servlet generating PNG image from stored JFreeChart session object.
 * @author Pawel Jurczyk
 *
 */
public class GraphsServlet extends HttpServlet {

    private static final long serialVersionUID = 1L;

    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {

        HttpSession session = request.getSession();
        OutputStream stream = response.getOutputStream();

        int width = Integer.parseInt(request.getParameter("width"));
        int height = Integer.parseInt(request.getParameter("height"));

        JFreeChart chart = (JFreeChart) session.getAttribute(GraphsBean.SESSION_KEY_GRAPH);

        if (chart == null) {
            response.encodeRedirectURL("../../images/blank.png");
            return;
        }

        response.setHeader("Cache-Control", "no-cache");
        response.setHeader("Cache-Control", "max-age=0");
        response.setHeader("Pragma", "no-cache");
        response.setDateHeader("Expires", 0);

        response.setContentType("image/png");
        ChartUtilities.writeChartAsPNG(stream, chart, width, height);

    }
}