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; }