fs = new POIFSFileSystem(is);
workbook = new HSSFWorkbook (fs);
StringBuilder builder = new StringBuilder();
for (int numSheets = 0; numSheets < workbook.getNumberOfSheets(); numSheets++) {
HSSFSheet sheet = workbook.getSheetAt(numSheets);
Iterator rows = sheet.rowIterator();
while( rows.hasNext() ) {
HSSFRow row = (HSSFRow) rows.next();
Iterator cells = row.cellIterator();
while( cells.hasNext() )
{