重构Java For循环代码以使用Java 8流API

Question

我有以下方法，该方法用于在数据库中创建订单，订单有很多项目，并且项目有很多账单。 iPadPOSOrderDTO是将要保存到数据库中的订单。

因此，用于创建订单的基于循环的代码如下

 private void createNewOrder(IPadPOSOrderDTO iPadPOSOrderDTO) {
    IPadPOSOrderV2 order = mapper.map(iPadPOSOrderDTO, IPadPOSOrderV2.class);
    if(order.getOrderV2Bills()!=null && order.getOrderV2Bills().size()>0){
        for(IPadPOSOrderV2Bill orderBill : order.getOrderV2Bills()){
            orderBill.setOrder(order);

            if(orderBill.getiPadPOSOrderV2BillItems()!=null && orderBill.getiPadPOSOrderV2BillItems().size()>0){
                for(IPadPOSOrderV2BillItems orderBillItem :  orderBill.getiPadPOSOrderV2BillItems()){
                    orderBillItem.setiPadPOSOrderV2Bill(orderBill);
                    orderBillItem.setOrderId(order.getOrderId());

                }
            }
        }
    }

    sessionFactory.
            getCurrentSession().save(order);
}

我想重构以上代码以使用Java 8流API。

所以，我做了以下

private void createNewOrderV2(IPadPOSOrderDTO iPadPOSOrderDTO) {
        IPadPOSOrderV2 order = mapper.map(iPadPOSOrderDTO, IPadPOSOrderV2.class);
        if(order.getOrderV2Bills()!=null && order.getOrderV2Bills().size()>0){
            order.getOrderV2Bills().stream().forEach(e -> { createBill(order,e);});
        }
        sessionFactory.
                getCurrentSession().save(order);
    }

    private void createBill(IPadPOSOrderV2 ipadExistingOrderFromDatabase, IPadPOSOrderV2Bill iPadPOSOrderV2Bill) {
        iPadPOSOrderV2Bill.setOrder(ipadExistingOrderFromDatabase);

        if(iPadPOSOrderV2Bill.getiPadPOSOrderV2BillItems()!=null && iPadPOSOrderV2Bill.getiPadPOSOrderV2BillItems().size()>0){
            iPadPOSOrderV2Bill.getiPadPOSOrderV2BillItems().stream().forEach(e -> createBillItem(ipadExistingOrderFromDatabase,iPadPOSOrderV2Bill,e));
        }
    }

    private void createBillItem(IPadPOSOrderV2 ipadExistingOrderFromDatabase, IPadPOSOrderV2Bill iPadPOSOrderV2Bill, IPadPOSOrderV2BillItems iPadPOSOrderV2BillItem) {
        iPadPOSOrderV2BillItem.setiPadPOSOrderV2Bill(iPadPOSOrderV2Bill);
        iPadPOSOrderV2BillItem.setOrderId(ipadExistingOrderFromDatabase.getOrderId());
        ipadExistingOrderFromDatabase.getOrderV2Bills().stream().forEach(e -> { createBill(ipadExistingOrderFromDatabase,e);});
    }

如果我在此重构中正确使用了流API，可以有人分享他们的经验并给我建议。

Answer 1

您可以使用集合的forEach。

     private void createNewOrderV2(IPadPOSOrderDTO iPadPOSOrderDTO) {
          IPadPOSOrderV2 order = mapper.map(iPadPOSOrderDTO, IPadPOSOrderV2.class);
          if (order.getOrderV2Bills() != null && !order.getOrderV2Bills().isEmpty()) {
             order.getOrderV2Bills().forEach(e -> createBill(order, e));
          }
       }

       private void createBill(IPadPOSOrderV2 ipadExistingOrderFromDatabase, IPadPOSOrderV2Bill iPadPOSOrderV2Bill) {
          iPadPOSOrderV2Bill.setOrder(ipadExistingOrderFromDatabase);
          List<IPadPOSOrderV2BillItems> iPadPOSOrderV2BillItems = iPadPOSOrderV2Bill.getiPadPOSOrderV2BillItems();
          if (iPadPOSOrderV2BillItems != null && !iPadPOSOrderV2BillItems.isEmpty()) {
             iPadPOSOrderV2BillItems.forEach(e -> createBillItem(ipadExistingOrderFromDatabase, iPadPOSOrderV2Bill, e));
          }
       }

       private void createBillItem(IPadPOSOrderV2 ipadExistingOrderFromDatabase, IPadPOSOrderV2Bill iPadPOSOrderV2Bill,
             IPadPOSOrderV2BillItems iPadPOSOrderV2BillItem) {
          iPadPOSOrderV2BillItem.setiPadPOSOrderV2Bill(iPadPOSOrderV2Bill);
          iPadPOSOrderV2BillItem.setOrderId(ipadExistingOrderFromDatabase.getOrderId());
          ipadExistingOrderFromDatabase.getOrderV2Bills().forEach(e -> createBill(ipadExistingOrderFromDatabase, e));
       }