public String generatePieChart(
      String hitOrdNum, HttpSession session, PrintWriter pw, String courseId, int studentId) {
    /* int groupId=0;
                if (groupName.equals("All")){
                    groupId=0;
                }else{
                     groupId = studStatisticBean.getGroupIdByName(groupName);
    }*/
    String filename = null;
    try {
      //  Retrieve list of WebHits
      StudentsConceptChartDataSet whDataSet =
          new StudentsConceptChartDataSet(studStatisticBean, courseId, studentId);
      ArrayList list = whDataSet.getDataBySection(hitOrdNum);

      //  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 PieDataSet
      DefaultPieDataset data = new DefaultPieDataset();
      Iterator iter = list.listIterator();
      while (iter.hasNext()) {
        StudentsConceptHit wh = (StudentsConceptHit) iter.next();
        data.setValue(wh.getSection(), wh.getHitDegree());
      }

      //  Create the chart object
      PiePlot plot = new PiePlot(data);
      plot.setInsets(new Insets(0, 5, 5, 5));
      plot.setURLGenerator(new StandardPieURLGenerator("xy_chart.jsp", "section"));
      plot.setToolTipGenerator(new StandardPieItemLabelGenerator());
      JFreeChart chart = new JFreeChart("", JFreeChart.DEFAULT_TITLE_FONT, plot, true);
      chart.setBackgroundPaint(java.awt.Color.white);

      //  Write the chart image to the temporary directory
      ChartRenderingInfo info = new ChartRenderingInfo(new StandardEntityCollection());
      filename = ServletUtilities.saveChartAsPNG(chart, 600, 400, 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;
  }
  public static String getSimplePieChart(Map dataSource, String objectName, HttpSession session)
      throws Throwable {
    DefaultPieDataset dataset = new DefaultPieDataset();

    Element chartObject =
        XMLHandler.getElementByAttribute(getChartObjectList(), "name", objectName);

    String title = chartObject.getAttributeValue("title");

    int width = Integer.parseInt(chartObject.getAttributeValue("width"));
    int height = Integer.parseInt(chartObject.getAttributeValue("height"));

    Element LabelKeys = chartObject.getChild("Labels");
    Element ValueKeys = chartObject.getChild("Values");

    String valueKey = ValueKeys.getText();
    String valueType = ValueKeys.getAttributeValue("type");
    List labelKeys = LabelKeys.getChildren("Label");
    String labelKey = LabelKeys.getText();

    if (valueType.equalsIgnoreCase("number")) {
      for (int i = 0; i < dataSource.size(); i++) {
        Map rec = (Map) dataSource.get("ROW" + i);
        Number value = (Number) rec.get(valueKey);
        String label;
        if (labelKeys.isEmpty()) {
          label = DataFilter.show(rec, labelKey);
        } else {
          label = ((Element) labelKeys.get(i)).getText();
        }
        dataset.setValue(label, value);
      }
    } else {
      for (int i = 0; i < dataSource.size(); i++) {
        Map rec = (Map) dataSource.get("ROW" + i);
        double value = (Double) rec.get(valueKey);
        String label;
        if (labelKeys.isEmpty()) {
          label = DataFilter.show(rec, labelKey);
        } else {
          label = ((Element) labelKeys.get(i)).getText();
        }
        dataset.setValue(label, value);
      }
    }

    JFreeChart chart =
        ChartFactory.createPieChart3D(
            title,
            dataset,
            chartObject.getAttribute("showLegend").getBooleanValue(),
            chartObject.getAttribute("showToolTips").getBooleanValue(),
            chartObject.getAttribute("urls").getBooleanValue());

    PiePlot3D pie3dplot = (PiePlot3D) chart.getPlot();

    float alpha = 0.7F;
    if (chartObject.getAttribute("alpha") != null) {
      alpha = chartObject.getAttribute("alpha").getFloatValue();
    }
    pie3dplot.setForegroundAlpha(alpha);

    return ServletUtilities.saveChartAsPNG(chart, width, height, null, session);
  }