skitrip.java

Java程序设计高级教程（第三版）

package com.nearhills;   

import javax.servlet.*;
import javax.servlet.http.*;

import java.text.*;
import java.util.*;

public class SkiTrip {

   public static final int AVAILABLE = 0;
   public static final int BOOKED = 1;
   public static final int FULL = 2;
   public static final int NOTRIP = 3;
   
   private int id;
   private Date date;
   private String resort;
   private int capacity;
   private int booked;
   static private Vector AllTrips = null;
   
   public SkiTrip() {}

   public static Vector getAllTrips() 
        throws DBopException 
   {
      if ( AllTrips == null ) {
         AllTrips = SkiClubDB.retrieveTrips();
      }
      return AllTrips;
   }

   public static SkiTrip getTrip( int id ) 
      throws DBopException
   {  
      Enumeration e = getAllTrips().elements();
      while ( e.hasMoreElements() ) {
         SkiTrip trip = ( SkiTrip ) e.nextElement();
         if ( trip.getId() == id ) {
            return trip;
         }
      }
      return null;
   }

   void setId( int id ) {
      this.id = id; 
   }
 
   public int getId( ) {
      return id;
   }

   void setDate( Date date ) {
      this.date = date; 
   }
 
   public Date getDate( ) {
      return date;
   }

   void setResort( String resort) {
      this.resort = resort;
   }

   public String getResort() {
      return resort;
   }

   void setCapacity( int capacity ) {
      this.capacity = capacity; 
   }
 
   public int getCapacity( ) {
      return capacity;
   }

   void setBooked( int booked ) {
      this.booked = booked; 
   }
   
   public String toString () 
   {
       DateFormat df = DateFormat.getDateInstance( 
          DateFormat.SHORT);
       String printable = "Ski on " ;
          printable += df.format(date) + "  ";
       while ( printable.length() < 16 ) {
       	  printable += " ";
       }
       printable += "at " + resort; 
       return printable; 
   }
 
   public int getBooked( ) {
      return booked;
   }

   public boolean isAvailable() {
      return ( getCapacity() > getBooked() );
   }

   public void addBooking() throws BookingException {
      if ( isAvailable() ) {
         setBooked( getBooked() + 1 );         
      } else {
         throw new BookingException (
            "Trip full, cannot add booking." );
      }
   }

   public void dropBooking() throws BookingException {
      if ( getBooked() > 0 ) {
         setBooked( getBooked() - 1 );         
      } else {
         throw new BookingException (
            "Trip not booked, cannot drop booking." );
      }
   }

   public static Vector getTrips( int skierID )
   {  
      Vector trips = null;
      try {
         trips = SkiClubDB.getSkierTrips( skierID);
      } catch ( Exception e ) {
         System.out.println ( e.getMessage() );
      }
      return trips;
   }    
}