HSSFWorkbook workbook = new HSSFWorkbook(fis);
int numOfSheets = workbook.getNumberOfSheets();
for(int i = 0; i < numOfSheets; i++) {
HSSFSheet sheet = workbook.getSheetAt(i);
Iterator rowIterator = sheet.rowIterator();
while (rowIterator.hasNext()) {
HSSFRow row = (HSSFRow)rowIterator.next();
Iterator cellIterator = row.cellIterator();