servletdemo1.java

在软件开发中用来绘制各种图表的源码

/* -----------------
 * ServletDemo1.java
 * -----------------
 * (C) Copyright 2002-2004, by Object Refinery Limited.
 *
 */

package demo;

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 org.jfree.chart.ChartFactory;
import org.jfree.chart.ChartUtilities;
import org.jfree.chart.JFreeChart;
import org.jfree.chart.plot.PlotOrientation;
import org.jfree.data.category.DefaultCategoryDataset;

/**
 * A basic servlet that returns a PNG image file generated by JFreeChart.
 * This class is described in the JFreeChart Developer Guide in the 
 * "Servlets" chapter.
 */
public class ServletDemo1 extends HttpServlet {

    /**
     * Creates a new demo.
     */
    public ServletDemo1() {
        // nothing required
    }

    /**
     * Processes a GET request.
     *
     * @param request  the request.
     * @param response  the response.
     *
     * @throws ServletException if there is a servlet related problem.
     * @throws IOException if there is an I/O problem.
     */
    public void doGet(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {

        OutputStream out = response.getOutputStream();
        try {
            DefaultCategoryDataset dataset = new DefaultCategoryDataset();
            dataset.addValue(10.0, "S1", "C1");
            dataset.addValue(4.0, "S1", "C2");
            dataset.addValue(15.0, "S1", "C3");
            dataset.addValue(14.0, "S1", "C4");
            dataset.addValue(-5.0, "S2", "C1");
            dataset.addValue(-7.0, "S2", "C2");
            dataset.addValue(14.0, "S2", "C3");
            dataset.addValue(-3.0, "S2", "C4");
            dataset.addValue(6.0, "S3", "C1");
            dataset.addValue(17.0, "S3", "C2");
            dataset.addValue(-12.0, "S3", "C3");
            dataset.addValue( 7.0, "S3", "C4");
            dataset.addValue(7.0, "S4", "C1");
            dataset.addValue(15.0, "S4", "C2");
            dataset.addValue(11.0, "S4", "C3");
            dataset.addValue(0.0, "S4", "C4");
            dataset.addValue(-8.0, "S5", "C1");
            dataset.addValue(-6.0, "S5", "C2");
            dataset.addValue(10.0, "S5", "C3");
            dataset.addValue(-9.0, "S5", "C4");
            dataset.addValue(9.0, "S6", "C1");
            dataset.addValue(8.0, "S6", "C2");
            dataset.addValue(null, "S6", "C3");
            dataset.addValue(6.0, "S6", "C4");
            dataset.addValue(-10.0, "S7", "C1");
            dataset.addValue(9.0, "S7", "C2");
            dataset.addValue(7.0, "S7", "C3");
            dataset.addValue(7.0, "S7", "C4");
            dataset.addValue(11.0, "S8", "C1");
            dataset.addValue(13.0, "S8", "C2");
            dataset.addValue(9.0, "S8", "C3");
            dataset.addValue(9.0, "S8", "C4");
            dataset.addValue(-3.0, "S9", "C1");
            dataset.addValue(7.0, "S9", "C2");
            dataset.addValue(11.0, "S9", "C3");
            dataset.addValue(-10.0, "S9", "C4");
            
            JFreeChart chart = ChartFactory.createBarChart(
                "Bar Chart",
                "Category",
                "Value",
                dataset,
                PlotOrientation.VERTICAL,
                true, true, false
            );
            response.setContentType("image/png");
            ChartUtilities.writeChartAsPNG(out, chart, 400, 300);
        }
        catch (Exception e) {
            System.err.println(e.toString());
        }
        finally {
            out.close();
        }

    }

}