org.openmrs.web.servlet.AbstractGraphServlet.java Source code

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Here is the source code for org.openmrs.web.servlet.AbstractGraphServlet.java

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/**
 * This Source Code Form is subject to the terms of the Mozilla Public License,
 * v. 2.0. If a copy of the MPL was not distributed with this file, You can
 * obtain one at http://mozilla.org/MPL/2.0/. OpenMRS is also distributed under
 * the terms of the Healthcare Disclaimer located at http://openmrs.org/license.
 *
 * Copyright (C) OpenMRS Inc. OpenMRS is a registered trademark and the OpenMRS
 * graphic logo is a trademark of OpenMRS Inc.
 */
package org.openmrs.web.servlet;

import java.io.IOException;

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

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.jfree.chart.ChartUtilities;
import org.jfree.chart.JFreeChart;

public abstract class AbstractGraphServlet extends HttpServlet {

    public static final long serialVersionUID = 1231231L;

    private Log log = LogFactory.getLog(AbstractGraphServlet.class);

    // Supported mime types
    public static final String PNG_MIME_TYPE = "image/png";

    public static final String JPG_MIME_TYPE = "image/jpeg";

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

        try {
            // Set default values
            Integer width = Integer.valueOf(500);
            Integer height = Integer.valueOf(300);
            String mimeType = PNG_MIME_TYPE;

            // Retrieve custom values
            try {
                width = Integer.parseInt(request.getParameter("width"));
            } catch (Exception e) {
                log.error("Error during width parseInt", e);
            }

            try {
                height = Integer.parseInt(request.getParameter("height"));
            } catch (Exception e) {
                log.error("Error during height parseInt", e);
            }

            if (request.getParameter("mimeType") != null) {
                mimeType = request.getParameter("mimeType");
            }

            JFreeChart chart = createChart(request, response);

            // Modify response to disable caching
            response.setHeader("Pragma", "No-cache");
            response.setDateHeader("Expires", 0);
            response.setHeader("Cache-Control", "no-cache");

            // Write chart out to response as image 
            try {
                if (JPG_MIME_TYPE.equalsIgnoreCase(mimeType)) {
                    response.setContentType(JPG_MIME_TYPE);
                    ChartUtilities.writeChartAsJPEG(response.getOutputStream(), chart, width, height);
                } else if (PNG_MIME_TYPE.equalsIgnoreCase(mimeType)) {
                    response.setContentType(PNG_MIME_TYPE);
                    ChartUtilities.writeChartAsPNG(response.getOutputStream(), chart, width, height);
                } else {
                    // Throw exception: unsupported mime type
                }
            } catch (IOException e) {
                log.error(e);
            }

        }
        // Add error handling above and remove this try/catch 
        catch (Exception e) {
            log.error(e);
        }
    }

    /**
     * Override this method for each graph
     * 
     * @param request
     * @param response
     * @return chart
     */
    protected abstract JFreeChart createChart(HttpServletRequest request, HttpServletResponse response);

    /**
     * 
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doGet(request, response);
    }

}