CommentBean


1   package edu.rice.rubis.beans;
2   
3   import java.rmi.*;
4   import javax.ejb.*;
5   import javax.rmi.PortableRemoteObject  ;
6   import javax.naming.InitialContext  ;
7   
8   /**
9    * BidBean is an entity bean with "container managed persistence". 
10   * The state of an instance is stored into a relational database. 
11   * The following table should exist:<p>
12   * <pre>
13   * CREATE TABLE comments (
14   *   id           INTEGER UNSIGNED NOT NULL UNIQUE,
15   *   from_user_id INTEGER,
16   *   to_user_id   INTEGER,
17   *   item_id      INTEGER,
18   *   rating       INTEGER,
19   *   date         DATETIME,
20   *   comment      TEXT
21   *   PRIMARY KEY(id),
22   *   INDEX from_user (from_user_id),
23   *   INDEX to_user (to_user_id),
24   *   INDEX item (item_id)
25   * );
26   * </pre>
27   * @author <a HREF="mailto:cecchet@rice.edu">Emmanuel Cecchet</a> and <a HREF="mailto:julie.marguerite@inrialpes.fr">Julie Marguerite</a>
28   * @version 1.0
29   */
30  
31  public class CommentBean implements EntityBean 
32  {
33    private EntityContext entityContext;
34    private transient boolean isDirty; // used for the isModified function
35    
36    /* Class member variables */
37  
38    public Integer   id;
39    public Integer   fromUserId;
40    public Integer   toUserId;
41    public Integer   itemId;
42    public int     rating;
43    public String    date;
44    public String    comment;
45  
46  
47    /**
48     * Get comment's id.
49     *
50     * @return comment id
51     * @exception RemoteException if an error occurs
52     */
53    public Integer   getId() throws RemoteException
54    {
55      return id;
56    }
57  
58    /**
59     * Get the user id of the author of the comment
60     *
61     * @return author user id
62     * @exception RemoteException if an error occurs
63     */
64    public Integer   getFromUserId() throws RemoteException
65    {
66      return fromUserId;
67    }
68  
69    /**
70     * Get the user id of the user this comment is about.
71     *
72     * @return user id this comment is about
73     * @exception RemoteException if an error occurs
74     */
75    public Integer   getToUserId() throws RemoteException
76    {
77      return toUserId;
78    }
79  
80    /**
81     * Get the item id which is the primary key in the items table.
82     *
83     * @return item id
84     * @exception RemoteException if an error occurs
85     */
86    public Integer   getItemId() throws RemoteException
87    {
88      return itemId;
89    }
90  
91    /**
92     * Get the rating associated to this comment.
93     *
94     * @return rating
95     * @exception RemoteException if an error occurs
96     */
97    public float getRating() throws RemoteException
98    {
99      return rating;
100   }
101 
102   /**
103    * Time of the Comment in the format 'YYYY-MM-DD hh:mm:ss'
104    *
105    * @return comment time
106    * @exception RemoteException if an error occurs
107    */
108   public String   getDate() throws RemoteException
109   {
110     return date;
111   }
112   
113   /**
114    * Get the comment text.
115    *
116    * @return comment text
117    * @exception RemoteException if an error occurs
118    */
119   public String   getComment() throws RemoteException
120   {
121     return comment;
122   }
123 
124 
125   /**
126    * Set a new user identifier for the author of the comment. 
127    * This id must match the primary key of the users table.
128    *
129    * @param id author user id
130    * @exception RemoteException if an error occurs
131    */
132   public void setFromUserId(Integer   id) throws RemoteException
133   {
134     fromUserId = id;
135     isDirty = true; // the bean content has been modified
136   }
137 
138   /**
139    * Set a new user identifier for the user this comment is about. 
140    * This id must match the primary key of the users table.
141    *
142    * @param id user id comment is about
143    * @exception RemoteException if an error occurs
144    */
145   public void setToUserId(Integer   id) throws RemoteException
146   {
147     toUserId = id;
148     isDirty = true; // the bean content has been modified
149   }
150 
151   /**
152    * Set a new item identifier. This id must match
153    * the primary key of the items table.
154    *
155    * @param id item id
156    * @exception RemoteException if an error occurs
157    */
158   public void setItemId(Integer   id) throws RemoteException
159   {
160     itemId = id;
161     isDirty = true; // the bean content has been modified
162   }
163 
164   /**
165    * Set a new rating for the ToUserId.
166    *
167    * @param Rating an <code>int</code> value
168    * @exception RemoteException if an error occurs
169    */
170   public void setRating(int Rating) throws RemoteException
171   {
172     rating = Rating;
173     isDirty = true; // the bean content has been modified
174   }
175 
176   /**
177    * Set a new date for this comment
178    *
179    * @param newDate comment date
180    * @exception RemoteException if an error occurs
181    */
182   public void setDate(String   newDate) throws RemoteException
183   {
184     date = newDate;
185     isDirty = true; // the bean content has been modified
186   }
187 
188   /**
189    * Set a new comment for ToUserId from FromUserId.
190    *
191    * @param newComment Comment
192    * @exception RemoteException if an error occurs
193    */
194   public void setComment(String   newComment) throws RemoteException
195   {
196     comment = newComment;
197     isDirty = true; // the bean content has been modified
198   }
199 
200 
201   /**
202    * This method is used to create a new Comment Bean. 
203    * The date is automatically set to the current date when the method is called.
204    *
205    * @param FromUserId user id of the comment author, must match the primary key of table users
206    * @param ToUserId user id of the user this comment is about, must match the primary key of table users
207    * @param ItemId item id, must match the primary key of table items
208    * @param Rating user (ToUserId) rating given by the author (FromUserId)
209    * @param Comment comment text
210    *
211    * @return pk primary key set to null
212    * @exception CreateException if an error occurs
213    * @exception RemoteException if an error occurs
214    * @exception RemoveException if an error occurs
215    */
216   public CommentPK ejbCreate(Integer   FromUserId, Integer   ToUserId, Integer   ItemId, int Rating, String   Comment) throws CreateException, RemoteException, RemoveException
217   {
218       // Connecting to IDManager Home interface thru JNDI
219       IDManagerHome home = null;
220       IDManager idManager = null;
221       
222       try 
223       {
224         InitialContext   initialContext = new InitialContext  ();
225         home = (IDManagerHome)PortableRemoteObject.narrow(initialContext.lookup(
226                "java:comp/env/ejb/IDManager"), IDManagerHome.class);
227       } 
228       catch (Exception   e)
229       {
230         throw new EJBException("Cannot lookup IDManager: " +e);
231       }
232      try 
233       {
234         IDManagerPK idPK = new IDManagerPK();
235         idManager = home.findByPrimaryKey(idPK);
236         id = idManager.getNextCommentID();
237         fromUserId = FromUserId;
238         toUserId   = ToUserId;
239         itemId     = ItemId;
240         rating     = Rating;
241         date       = TimeManagement.currentDateToString();
242         comment    = Comment;
243       } 
244       catch (Exception   e)
245       {
246         throw new EJBException("Cannot create comment: " +e);
247       }
248     return null;
249   }
250 
251   /** This method just set an internal flag to 
252       reload the id generated by the DB */
253   public void ejbPostCreate(Integer   FromUserId, Integer   ToUserId, Integer   ItemId, int Rating, String   Comment)
254   {
255     isDirty = true; // the id has to be reloaded from the DB
256   }
257 
258   /** Persistence is managed by the container and the bean
259       becomes up to date */
260   public void ejbLoad() throws RemoteException 
261   {
262     isDirty = false;
263   }
264 
265   /** Persistence is managed by the container and the bean
266       becomes up to date */
267   public void ejbStore() throws RemoteException
268   {
269     isDirty = false;
270   }
271 
272   /** This method is empty because persistence is managed by the container */
273   public void ejbActivate() throws RemoteException {}
274   /** This method is empty because persistence is managed by the container */
275   public void ejbPassivate() throws RemoteException {}
276   /** This method is empty because persistence is managed by the container */
277   public void ejbRemove() throws RemoteException, RemoveException {}
278 
279   /**
280    * Sets the associated entity context. The container invokes this method 
281    *  on an instance after the instance has been created. 
282    * 
283    * This method is called in an unspecified transaction context. 
284    * 
285    * @param context An EntityContext interface for the instance. The instance should 
286    *                store the reference to the context in an instance variable. 
287    * @exception EJBException  Thrown by the method to indicate a failure 
288    *                          caused by a system-level error.
289    * @exception RemoteException - This exception is defined in the method signature
290    *                           to provide backward compatibility for enterprise beans
291    *                           written for the EJB 1.0 specification. 
292    *                           Enterprise beans written for the EJB 1.1 and 
293    *                           higher specification should throw the javax.ejb.EJBException 
294    *                           instead of this exception. 
295    */
296   public void setEntityContext(EntityContext context) throws RemoteException
297   {
298     entityContext = context;
299   }
300 
301   /**
302    * Unsets the associated entity context. The container calls this method 
303    *  before removing the instance. This is the last method that the container 
304    *  invokes on the instance. The Java garbage collector will eventually invoke 
305    *  the finalize() method on the instance. 
306    *
307    * This method is called in an unspecified transaction context. 
308    * 
309    * @exception EJBException  Thrown by the method to indicate a failure 
310    *                          caused by a system-level error.
311    * @exception RemoteException - This exception is defined in the method signature
312    *                           to provide backward compatibility for enterprise beans
313    *                           written for the EJB 1.0 specification. 
314    *                           Enterprise beans written for the EJB 1.1 and 
315    *                           higher specification should throw the javax.ejb.EJBException 
316    *                           instead of this exception.
317    */
318   public void unsetEntityContext() throws RemoteException
319   {
320     entityContext = null;
321   }
322 
323   /**
324    * Returns true if the beans has been modified.
325    * It prevents the EJB server from reloading a bean
326    * that has not been modified.
327    *
328    * @return a <code>boolean</code> value
329    */
330   public boolean isModified() 
331   {
332     return isDirty;
333   }
334 
335 
336   /**
337    * Display comment information as an HTML table row
338    *
339    * @return a <code>String</code> containing HTML code
340    * @exception RemoteException if an error occurs
341    * @since 1.0
342    */
343   public String   printComment(String   userName) throws RemoteException
344   {
345     return "<DT><b><BIG><a HREF=\""+BeanConfig.context+"/servlet/edu.rice.rubis.beans.servlets.ViewUserInfo?userId="+fromUserId+"\">"+userName+"</a></BIG></b>"+
346       " wrote the "+date+"<DD><i>"+comment+"</i><p>\n";
347   }
348 }
349
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