public ArrayList<PaymentPO> findPayment(Calendar start, Calendar end) // 时间参数与findIncome相同
     throws RemoteException {
   ResultSet result = mysqlSer.checkDate(start, end, POKind.PAYMENT);
   return ArrayListFactory.producePaymentList(result);
 }
 public ArrayList<IncomePO> findIncome(Calendar start, Calendar end) // 时间参数与findPayment相同
     throws RemoteException {
   ResultSet result = mysqlSer.checkDate(start, end, POKind.INCOME);
   return ArrayListFactory.produceIncomeList(result);
 }