if(chart == null) throw new IllegalStateException("chart not found in the template");
// embedded Excel workbook that holds the chart data
POIXMLDocumentPart xlsPart = chart.getRelations().get(0);
XSSFWorkbook wb = new XSSFWorkbook();
XSSFSheet sheet = wb.createSheet();
CTChart ctChart = chart.getCTChart();
CTPlotArea plotArea = ctChart.getPlotArea();
CTPieChart pieChart = plotArea.getPieChartArray(0);
//Pie Chart Series
CTPieSer ser = pieChart.getSerArray(0);
// Series Text
CTSerTx tx = ser.getTx();
tx.getStrRef().getStrCache().getPtArray(0).setV(chartTitle);
sheet.createRow(0).createCell(1).setCellValue(chartTitle);
String titleRef = new CellReference(sheet.getSheetName(), 0, 1, true, true).formatAsString();
tx.getStrRef().setF(titleRef);
// Category Axis Data
CTAxDataSource cat = ser.getCat();
CTStrData strData = cat.getStrRef().getStrCache();
// Values
CTNumDataSource valSrc = ser.getVal();
CTNumData numData = valSrc.getNumRef().getNumCache();
strData.setPtArray(null); // unset old axis text
numData.setPtArray(null); // unset old values
Map<String, Double> pieModel = new LinkedHashMap<String, Double>();
pieModel.put("First", 1.0);
pieModel.put("Second", 3.0);
pieModel.put("Third", 4.0);
// set model
int idx = 0;
int rownum = 1;
for(String key : pieModel.keySet()){
double val = pieModel.get(key);
CTNumVal numVal = numData.addNewPt();
numVal.setIdx(idx);
numVal.setV("" + val);
CTStrVal sVal = strData.addNewPt();
sVal.setIdx(idx);
sVal.setV(key);
idx++;
XSSFRow row = sheet.createRow(rownum++);
row.createCell(0).setCellValue(key);
row.createCell(1).setCellValue(val);
}
numData.getPtCount().setVal(idx);
strData.getPtCount().setVal(idx);
String numDataRange = new CellRangeAddress(1, rownum-1, 1, 1).formatAsString(sheet.getSheetName(), true);
valSrc.getNumRef().setF(numDataRange);
String axisDataRange = new CellRangeAddress(1, rownum-1, 0, 0).formatAsString(sheet.getSheetName(), true);
cat.getStrRef().setF(axisDataRange);
// updated the embedded workbook with the data
OutputStream xlsOut = xlsPart.getPackagePart().getOutputStream();
wb.write(xlsOut);