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Bar Chart Creation Code
From org.jfree.chart.demo.servlet.WebHitChart (See also bar_chart.jsp)
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public static String generateBarChart(Date hitDate, HttpSession session, PrintWriter pw) {
String filename = null;
try {
// Retrieve list of WebHits
WebHitDataSet whDataSet = new WebHitDataSet();
ArrayList list = whDataSet.getDataBySection(hitDate);
// Throw a custom NoDataException if there is no data
if (list.size() == 0) {
System.out.println("No data has been found");
throw new NoDataException();
}
// Create and populate a CategoryDataset
Iterator iter = list.listIterator();
DefaultCategoryDataset dataset = new DefaultCategoryDataset();
while (iter.hasNext()) {
WebHit wh = (WebHit)iter.next();
dataset.addValue(new Long(wh.getHitCount()), "Hits", wh.getSection());
}
// Create the chart object
CategoryAxis categoryAxis = new CategoryAxis("");
ValueAxis valueAxis = new NumberAxis("");
BarRenderer renderer = new BarRenderer();
renderer.setItemURLGenerator(new StandardCategoryURLGenerator("xy_chart.jsp","series","section"));
renderer.setToolTipGenerator(new StandardCategoryToolTipGenerator());
Plot plot = new CategoryPlot(dataset, categoryAxis, valueAxis, renderer);
JFreeChart chart = new JFreeChart("", JFreeChart.DEFAULT_TITLE_FONT, plot, false);
chart.setBackgroundPaint(java.awt.Color.white);
// Write the chart image to the temporary directory
ChartRenderingInfo info = new ChartRenderingInfo(new StandardEntityCollection());
filename = ServletUtilities.saveChartAsPNG(chart, 500, 300, info, session);
// Write the image map to the PrintWriter
ChartUtilities.writeImageMap(pw, filename, info);
pw.flush();
} catch (NoDataException e) {
System.out.println(e.toString());
filename = "public_nodata_500x300.png";
} catch (Exception e) {
System.out.println("Exception - " + e.toString());
e.printStackTrace(System.out);
filename = "public_error_500x300.png";
}
return filename;
}
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