BidBean


1   package edu.rice.rubis.beans;
2   
3   import java.rmi.*;
4   import javax.ejb.*;
5   import javax.naming.Context  ;
6   import javax.naming.InitialContext  ;
7   import javax.rmi.PortableRemoteObject  ;
8   
9   /**
10   * BidBean is an entity bean with "container managed persistence". 
11   * The state of an instance is stored into a relational database. 
12   * The following table should exist:<p>
13   * <pre>
14   * CREATE TABLE bids (
15   *    id      INTEGER UNSIGNED NOT NULL UNIQUE,
16   *    user_id INTEGER,
17   *    item_id INTEGER,
18   *    qty     INTEGER,
19   *    bid     FLOAT UNSIGNED NOT NULL,
20   *    max_bid FLOAT UNSIGNED NOT NULL,
21   *    date    DATETIME
22   *   INDEX item (item_id),
23   *   INDEX user (user_id)
24   * );
25   * </pre>
26   * @author <a HREF="mailto:cecchet@rice.edu">Emmanuel Cecchet</a> and <a HREF="mailto:julie.marguerite@inrialpes.fr">Julie Marguerite</a>
27   * @version 1.0
28   */
29  
30  public class BidBean implements EntityBean 
31  {
32    private EntityContext entityContext;
33    private transient boolean isDirty; // used for the isModified function
34  
35    /* Class member variables */
36  
37    public Integer   id;
38    public Integer   userId;
39    public Integer   itemId;
40    public int     qty;
41    public float   bid;
42    public float   maxBid;
43    public String    date;
44  
45    
46    /**
47     * Get bid's id.
48     *
49     * @return bid id
50     * @exception RemoteException if an error occurs
51     */
52    public Integer   getId() throws RemoteException
53    {
54      return id;
55    }
56  
57    /**
58     * Get the user id which is the primary key in the users table.
59     *
60     * @return user id
61     * @exception RemoteException if an error occurs
62     */
63    public Integer   getUserId() throws RemoteException
64    {
65      return userId;
66    }
67  
68    /**
69     * Get the item id which is the primary key in the items table.
70     *
71     * @return item id
72     * @exception RemoteException if an error occurs
73     */
74    public Integer   getItemId() throws RemoteException
75    {
76      return itemId;
77    }
78  
79    /**
80     * Get how many of this item the user wants.
81     *
82     * @return quantity of items for this bid.
83     * @exception RemoteException if an error occurs
84     */
85    public int getQuantity() throws RemoteException
86    {
87      return qty;
88    }
89  
90    /**
91     * Get the bid of the user.
92     *
93     * @return user's bid
94     * @exception RemoteException if an error occurs
95     */
96    public float getBid() throws RemoteException
97    {
98      return bid;
99    }
100 
101   /**
102    * Get the maximum bid wanted by the user.
103    *
104    * @return user's maximum bid
105    * @exception RemoteException if an error occurs
106    */
107   public float getMaxBid() throws RemoteException
108   {
109     return maxBid;
110   }
111 
112   /**
113    * Time of the Bid in the format 'YYYY-MM-DD hh:mm:ss'
114    *
115    * @return bid time
116    * @exception RemoteException if an error occurs
117    */
118   public String   getDate() throws RemoteException
119   {
120     return date;
121   }
122 
123   /**
124    * Give the nick name of the bidder
125    *
126    * @return bidder's nick name
127    * @exception RemoteException if an error occurs
128    */
129   public String   getBidderNickName() throws RemoteException
130   {
131     Context   initialContext = null;
132     try
133     {
134       initialContext = new InitialContext  ();
135     } 
136     catch (Exception   e) 
137     {
138       System.err.print("Cannot get initial context for JNDI: " + e);
139       return null;
140     }
141 
142     // Try to find the user nick name corresponding to the sellerId
143     UserHome uHome;
144     try 
145     {
146       uHome = (UserHome)PortableRemoteObject.narrow(initialContext.lookup("UserHome"),
147                                                     UserHome.class);
148     } 
149     catch (Exception   e)
150     {
151       System.err.print("Cannot lookup User: " +e);
152       return null;
153     }
154     try
155     {
156       User u = uHome.findByPrimaryKey(new UserPK(userId));
157       return u.getNickName();
158     }
159     catch (Exception   e)
160     {
161       System.err.print("This user does not exist (got exception: " +e+")<br>");
162       return null;
163     }
164   }
165 
166 
167   /**
168    * Set a new user identifier. This id must match
169    * the primary key of the users table.
170    *
171    * @param id user id
172    * @exception RemoteException if an error occurs
173    */
174   public void setUserId(Integer   id) throws RemoteException
175   {
176     userId = id;
177     isDirty = true; // the bean content has been modified
178   }
179 
180   /**
181    * Set a new item identifier. This id must match
182    * the primary key of the items table.
183    *
184    * @param id item id
185    * @exception RemoteException if an error occurs
186    */
187   public void setItemId(Integer   id) throws RemoteException
188   {
189     itemId = id;
190     isDirty = true; // the bean content has been modified
191   }
192 
193   /**
194    * Set a new quantity for this bid
195    *
196    * @param Qty quantity
197    * @exception RemoteException if an error occurs
198    */
199   public void setQuantity(int Qty) throws RemoteException
200   {
201     qty = Qty;
202     isDirty = true; // the bean content has been modified
203   }
204 
205   /**
206    * Set a new bid on the item for the user.
207    * <pre>
208    * Warning! This method does not update the maxBid value in the items table
209    * </pre>
210    *
211    * @param newBid a <code>float</code> value
212    * @exception RemoteException if an error occurs
213    */
214   public void setBid(float newBid) throws RemoteException
215   {
216     bid = newBid;
217     isDirty = true; // the bean content has been modified
218   }
219 
220   /**
221    * Set a new maximum bid on the item for the user
222    *
223    * @param newBid a <code>float</code> value
224    * @exception RemoteException if an error occurs
225    */
226   public void setMaxBid(float newBid) throws RemoteException
227   {
228     maxBid = newBid;
229     isDirty = true; // the bean content has been modified
230   }
231 
232   /**
233    * Set a new date for this bid
234    *
235    * @param newDate bid date
236    * @exception RemoteException if an error occurs
237    */
238   public void setDate(String   newDate) throws RemoteException
239   {
240     date = newDate;
241     isDirty = true; // the bean content has been modified
242   }
243 
244 
245   /**
246    * This method is used to create a new Bid Bean.
247    * The date is automatically set to the current date when the method is called.
248    *
249    * @param bidUserId user id of the bidder, must match the primary key of table users
250    * @param bidItemId item id, must match the primary key of table items
251    * @param userBid the amount of the user bid
252    * @param userMaxBid the maximum amount the user wants to bid
253    * @param quantity number of items the user wants to buy
254    *
255    * @return pk primary key set to null
256    * @exception CreateException if an error occurs
257    * @exception RemoteException if an error occurs
258    * @exception RemoveException if an error occurs
259    */
260   public BidPK ejbCreate(Integer   bidUserId, Integer   bidItemId, float userBid, float userMaxBid, int quantity) throws CreateException, RemoteException, RemoveException
261   {
262     Item item;
263     InitialContext   initialContext = null;
264     // Find the item to update its maxBid and nbOfBids
265     try
266     {
267       initialContext = new InitialContext  ();
268       ItemHome iHome = (ItemHome)PortableRemoteObject.narrow(initialContext.lookup("ItemHome"), ItemHome.class);
269       item = iHome.findByPrimaryKey(new ItemPK(bidItemId));
270     }
271     catch (Exception   e) 
272     {
273       throw new CreateException("Error while getting item id "+bidItemId+" in BidBean: " + e+"<br>");
274     }
275     item.setMaxBid(userBid);
276     item.addOneBid();
277 
278      // Connecting to IDManager Home interface thru JNDI
279       IDManagerHome home = null;
280       IDManager idManager = null;
281       
282       try 
283       {
284         home = (IDManagerHome)PortableRemoteObject.narrow(initialContext.lookup(
285                "java:comp/env/ejb/IDManager"), IDManagerHome.class);
286       } 
287       catch (Exception   e)
288       {
289         throw new EJBException("Cannot lookup IDManager: " +e);
290       }
291      try 
292       {
293         IDManagerPK idPK = new IDManagerPK();
294         idManager = home.findByPrimaryKey(idPK);
295         id = idManager.getNextBidID();
296         userId = bidUserId;
297         itemId = bidItemId;
298         bid    = userBid;
299         maxBid = userMaxBid;
300         qty    = quantity;
301         date   = TimeManagement.currentDateToString();
302       } 
303      catch (Exception   e)
304      {
305        throw new EJBException("Cannot create bid: " +e);
306      }
307     return null;
308   }
309 
310 
311   /** This method just set an internal flag to 
312       reload the id generated by the DB */
313   public void ejbPostCreate(Integer   bidUserId, Integer   bidItemId, float userBid, float userMaxBid, int quantity) 
314   {
315     isDirty = true; // the id has to be reloaded from the DB
316   }
317 
318   /** Persistence is managed by the container and the bean
319       becomes up to date */
320   public void ejbLoad() throws RemoteException 
321   {
322     isDirty = false;
323   }
324 
325   /** Persistence is managed by the container and the bean
326       becomes up to date */
327   public void ejbStore() throws RemoteException
328   {
329     isDirty = false;
330   }
331 
332   /** This method is empty because persistence is managed by the container */
333   public void ejbActivate() throws RemoteException {}
334   /** This method is empty because persistence is managed by the container */
335   public void ejbPassivate() throws RemoteException  {}
336   /** This method is empty because persistence is managed by the container */
337   public void ejbRemove() throws RemoteException, RemoveException {}
338 
339   /**
340    * Sets the associated entity context. The container invokes this method 
341    *  on an instance after the instance has been created. 
342    * 
343    * This method is called in an unspecified transaction context. 
344    * 
345    * @param context An EntityContext interface for the instance. The instance should 
346    *              store the reference to the context in an instance variable. 
347    * @exception EJBException  Thrown by the method to indicate a failure 
348    *                          caused by a system-level error.
349    * @exception RemoteException - This exception is defined in the method signature
350    *                           to provide backward compatibility for enterprise beans
351    *                           written for the EJB 1.0 specification. 
352    *                           Enterprise beans written for the EJB 1.1 and 
353    *                           higher specification should throw the javax.ejb.EJBException 
354    *                           instead of this exception. 
355    */
356   public void setEntityContext(EntityContext context) throws RemoteException
357   {
358     entityContext = context;
359   }
360 
361   /**
362    * Unsets the associated entity context. The container calls this method 
363    *  before removing the instance. This is the last method that the container 
364    *  invokes on the instance. The Java garbage collector will eventually invoke 
365    *  the finalize() method on the instance. 
366    *
367    * This method is called in an unspecified transaction context. 
368    * 
369    * @exception EJBException  Thrown by the method to indicate a failure 
370    *                          caused by a system-level error.
371    * @exception RemoteException - This exception is defined in the method signature
372    *                           to provide backward compatibility for enterprise beans
373    *                           written for the EJB 1.0 specification. 
374    *                           Enterprise beans written for the EJB 1.1 and 
375    *                           higher specification should throw the javax.ejb.EJBException 
376    *                           instead of this exception.
377    */
378   public void unsetEntityContext() throws RemoteException
379   {
380     entityContext = null;
381   }
382 
383 
384   /**
385    * Returns true if the beans has been modified.
386    * It prevents the EJB server from reloading a bean
387    * that has not been modified.
388    *
389    * @return a <code>boolean</code> value
390    */
391   public boolean isModified() 
392   {
393     return isDirty;
394   }
395 
396 
397   /**
398    * Display bid history information as an HTML table row
399    *
400    * @return a <code>String</code> containing HTML code
401    * @exception RemoteException if an error occurs
402    * @since 1.0
403    */
404   public String   printBidHistory() throws RemoteException
405   {
406     return "<TR><TD><a HREF=\""+BeanConfig.context+"/servlet/edu.rice.rubis.beans.servlets.ViewUserInfo?userId="+userId+
407       "\">"+getBidderNickName()+"<TD>"+bid+"<TD>"+date+"\n";
408   }
409 }
410
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