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jfreechart example source code file (DisplayChart.java)

This example jfreechart source code file (DisplayChart.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - jfreechart tags/keywords

chart, chartdeleter, chartdeleter, displaychart, displaychart, file, file, http, httpservletresponse, httpsession, io, jfreechart_deleter, parameter, request, response, servlet, servletexception, servletexception, string

The jfreechart DisplayChart.java source code

/* ===========================================================
 * JFreeChart : a free chart library for the Java(tm) platform
 * ===========================================================
 *
 * (C) Copyright 2000-2008, by Object Refinery Limited and Contributors.
 *
 * Project Info:  http://www.jfree.org/jfreechart/index.html
 *
 * This library is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation; either version 2.1 of the License, or
 * (at your option) any later version.
 *
 * This library 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 Lesser General Public
 * License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
 * USA.
 *
 * [Java is a trademark or registered trademark of Sun Microsystems, Inc.
 * in the United States and other countries.]
 *
 * -----------------
 * DisplayChart.java
 * -----------------
 * (C) Copyright 2002-2008, by Richard Atkinson and Contributors.
 *
 * Original Author:  Richard Atkinson;
 * Contributor(s):   David Gilbert (for Object Refinery Limited);
 *
 * Changes
 * -------
 * 19-Aug-2002 : Version 1;
 * 09-Mar-2005 : Added facility to serve up "one time" charts - see
 *               ServletUtilities.java (DG);
 * ------------- JFREECHART 1.0.x ---------------------------------------------
 * 02-Feb-2007 : Removed author tags all over JFreeChart sources (DG);
 *
 */

package org.jfree.chart.servlet;

import java.io.File;
import java.io.IOException;

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

/**
 * Servlet used for streaming charts to the client browser from the temporary
 * directory.  You need to add this servlet and mapping to your deployment
 * descriptor (web.xml) in order to get it to work.  The syntax is as follows:
 * <xmp>
 * <servlet>
 *    <servlet-name>DisplayChart
 *    <servlet-class>org.jfree.chart.servlet.DisplayChart
 * </servlet>
 * <servlet-mapping>
 *     <servlet-name>DisplayChart
 *     <url-pattern>/servlet/DisplayChart
 * </servlet-mapping>
 * </xmp>
 */
public class DisplayChart extends HttpServlet {

    /**
     * Default constructor.
     */
    public DisplayChart() {
        super();
    }

    /**
     * Init method.
     *
     * @throws ServletException never.
     */
    public void init() throws ServletException {
        return;
    }

    /**
     * Service method.
     *
     * @param request  the request.
     * @param response  the response.
     *
     * @throws ServletException ??.
     * @throws IOException ??.
     */
    public void service(HttpServletRequest request,
                        HttpServletResponse response)
            throws ServletException, IOException {

        HttpSession session = request.getSession();
        String filename = request.getParameter("filename");

        if (filename == null) {
            throw new ServletException("Parameter 'filename' must be supplied");
        }

        //  Replace ".." with ""
        //  This is to prevent access to the rest of the file system
        filename = ServletUtilities.searchReplace(filename, "..", "");

        //  Check the file exists
        File file = new File(System.getProperty("java.io.tmpdir"), filename);
        if (!file.exists()) {
            throw new ServletException("File '" + file.getAbsolutePath()
                    + "' does not exist");
        }

        //  Check that the graph being served was created by the current user
        //  or that it begins with "public"
        boolean isChartInUserList = false;
        ChartDeleter chartDeleter = (ChartDeleter) session.getAttribute(
                "JFreeChart_Deleter");
        if (chartDeleter != null) {
            isChartInUserList = chartDeleter.isChartAvailable(filename);
        }

        boolean isChartPublic = false;
        if (filename.length() >= 6) {
            if (filename.substring(0, 6).equals("public")) {
                isChartPublic = true;
            }
        }

        boolean isOneTimeChart = false;
        if (filename.startsWith(ServletUtilities.getTempOneTimeFilePrefix())) {
            isOneTimeChart = true;
        }

        if (isChartInUserList || isChartPublic || isOneTimeChart) {
            //  Serve it up
            ServletUtilities.sendTempFile(file, response);
            if (isOneTimeChart) {
                file.delete();
            }
        }
        else {
            throw new ServletException("Chart image not found");
        }
        return;
    }

}

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