deliveryorderdatabase.java

J2ME MIDP_Example_Applications

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package example.delivery;

import java.util.*;


public class DeliveryOrderDatabase 
{
    private Map deliveryOrders = null;
    private Random random;


    public DeliveryOrderDatabase()
    {
        random = new Random();

        // A TreeMap guarantees ascending ordering by the key.
        // That's useful since DeliveryOrders should be processed
        // in a time ordered manner. (A List could also be used.)
        //
        // The TreeMap class's implementation is not synchronized.
        // It should be externally synchronized. The following is sufficient
        // for this prototype, but note that "ConcurrentModificationException"
        // notifications are never caught in this prototype. A more robust
        // implementation would be needed for an implementation that
        // scales to N potential users concurrently adding/deleting elements,
        // but a more robust implementation would likely use a real database
        // instead anyways.
        //
        deliveryOrders = Collections.synchronizedMap(new TreeMap());
    }


    public DeliveryOrder createDeliveryOrder(String description,
                                             String senderAddress,
                                             String recipientAddress,
                                             String note)
    {
        String id = createDeliveryOrderId();

        Date openedTime = new Date();

        DeliveryOrder deliveryOrder =
            new DeliveryOrder(
                    id,
                    DeliveryOrder.OPENED,
                    openedTime.toString(),
                    description,
                    senderAddress,
                    recipientAddress,
                    note
                );
        deliveryOrders.put(id, deliveryOrder);

        return deliveryOrder;
    }


    private String createDeliveryOrderId()
    {
        Date current = new Date();
        int num = random.nextInt();
        if (num < 0)
        {
          num = -num;
        }
        return("" + current.getTime() + "_" + num);
    }


    // Return null if none found, else return DeliveryOrder
    // assigned to courier.
    protected synchronized DeliveryOrder getDeliveryJob(String courierName)
    {
       DeliveryOrder assignment = null;  // default: no assignment to give

       assignment = getExistingJob(courierName);
       if (assignment == null)
       {
           assignment = getNewJob(courierName);
       }

       return assignment;
    }


    protected synchronized DeliveryOrder getExistingJob(String courierName)
    {
       Set keySet = deliveryOrders.keySet();
       if (!keySet.isEmpty() && (courierName != null))
       {
           Iterator iterator = keySet.iterator();
           while (iterator.hasNext())
           {
               String id = (String)iterator.next();
               DeliveryOrder req = (DeliveryOrder)deliveryOrders.get(id);
               if (req != null)
               {
                   String name = req.getCourierName();
                   String status = req.getStatus();

                   if ((name!=null) &&
                      (CourierDatabase.canonicalForm(name).equals(
                       CourierDatabase.canonicalForm(courierName))))
                   {
                       if (status.equals(DeliveryOrder.ASSIGNED) ||
                           status.equals(DeliveryOrder.PICKEDUP) ||
                           status.equals(DeliveryOrder.COURIERCANCELLED))
                       {
                           return req;
                       }
                   }
               }
           }
       }

       return null; // no existing assignment found for this courier
    }


    protected synchronized DeliveryOrder getNewJob(String courierName)
    {
       Set keySet = deliveryOrders.keySet();
       if (!keySet.isEmpty() && (courierName != null))
       {
           Iterator iterator = keySet.iterator();
           while (iterator.hasNext())
           {
               String id = (String)iterator.next();
               DeliveryOrder req = (DeliveryOrder)deliveryOrders.get(id);
               if (req != null)
               {
                   String status = req.getStatus();
                   if (status.equals(DeliveryOrder.OPENED))
                   {
                       // assign an OPENED request to a courier

                       req.setStatus(DeliveryOrder.ASSIGNED);
                       req.setCourierName(courierName);
                       deliveryOrders.remove(req.getId());
                       deliveryOrders.put(req.getId(), req);
                       return req;
                   }
               }
           }
       }

       return null; // no 'OPENED' assignments available
    }


    public void deleteDeliveryOrder(DeliveryOrder deliveryOrder)
    {
        deliveryOrders.remove(deliveryOrder.getId());
    }


    public DeliveryOrder getDeliveryOrder(String id)
    {
        return (DeliveryOrder)(deliveryOrders.get(id));
    }


    public Collection getAllDeliveryOrders()
    {
        return deliveryOrders.values();
    }

}