CategoryBean


1   package edu.rice.rubis.beans;
2   
3   import java.net.URLEncoder  ;
4   import java.rmi.*;
5   import javax.ejb.*;
6   import javax.rmi.PortableRemoteObject  ;
7   import javax.naming.InitialContext  ;
8   
9   /**
10   * CategoryBean 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 categories (
15   *    id   INTEGER UNSIGNED NOT NULL UNIQUE,
16   *    name VARCHAR(50),
17   *    PRIMARY KEY(id)
18   * );
19   * </pre>
20   * @author <a HREF="mailto:cecchet@rice.edu">Emmanuel Cecchet</a> and <a HREF="mailto:julie.marguerite@inrialpes.fr">Julie Marguerite</a>
21   * @version 1.0
22   */
23  
24  public class CategoryBean implements EntityBean 
25  {
26    private EntityContext entityContext;
27    private transient boolean isDirty; // used for the isModified function
28  
29    /* Class member variables */
30  
31    public Integer   id;
32    public String    name;
33  
34  
35    /**
36     * Get category's id.
37     *
38     * @return category id
39     * @exception RemoteException if an error occurs
40     */
41    public Integer   getId() throws RemoteException
42    {
43      return id;
44    }
45  
46    /**
47     * Get the category name.
48     *
49     * @return category name
50     * @exception RemoteException if an error occurs
51     */
52    public String   getName() throws RemoteException
53    {
54      return name;
55    }
56  
57    /**
58     * Set category's name
59     *
60     * @param newName category name
61     * @exception RemoteException if an error occurs
62     */
63    public void setName(String   newName) throws RemoteException 
64    {
65      name = newName;
66      isDirty = true; // the bean content has been modified
67    }
68  
69  
70    /**
71     * This method is used to create a new Category Bean. Note that the category
72     * id is automatically generated by the database (AUTO_INCREMENT) on the
73     * primary key.
74     *
75     * @param categoryName Category name
76     *
77     * @return pk primary key set to null
78     * @exception CreateException if an error occurs
79     * @exception RemoteException if an error occurs
80     * @exception RemoveException if an error occurs
81     */
82    public CategoryPK ejbCreate(String   categoryName) throws CreateException, RemoteException, RemoveException
83    {
84        // Connecting to IDManager Home interface thru JNDI
85        IDManagerHome home = null;
86        IDManager idManager = null;
87        
88        try 
89        {
90          InitialContext   initialContext = new InitialContext  ();
91          home = (IDManagerHome)PortableRemoteObject.narrow(initialContext.lookup(
92                 "java:comp/env/ejb/IDManager"), IDManagerHome.class);
93        } 
94        catch (Exception   e)
95        {
96          throw new RemoteException("Cannot lookup IDManager: " +e);
97        }
98       try 
99        {
100         IDManagerPK idPK = new IDManagerPK();
101         idManager = home.findByPrimaryKey(idPK);
102         id = idManager.getNextCategoryID();
103         name = categoryName;
104       } 
105       catch (Exception   e)
106       {
107         throw new RemoteException("Cannot create category: " +e);
108       }
109       return null; 
110   }
111 
112 
113   /** This method just set an internal flag to 
114       reload the id generated by the DB */
115   public void ejbPostCreate(String   categoryName)
116   {
117     isDirty = true; // the id has to be reloaded from the DB
118   }
119 
120   /** Persistence is managed by the container and the bean
121       becomes up to date */
122   public void ejbLoad() throws RemoteException 
123   {
124     isDirty = false;
125   }
126 
127   /** Persistence is managed by the container and the bean
128       becomes up to date */
129   public void ejbStore() throws RemoteException
130   {
131     isDirty = false;
132   }
133 
134   /** This method is empty because persistence is managed by the container */
135   public void ejbActivate() throws RemoteException {}
136   /** This method is empty because persistence is managed by the container */
137   public void ejbPassivate() throws RemoteException {}
138   /** This method is empty because persistence is managed by the container */
139   public void ejbRemove() throws RemoteException, RemoveException {}
140 
141   /**
142    * Sets the associated entity context. The container invokes this method 
143    *  on an instance after the instance has been created. 
144    * 
145    * This method is called in an unspecified transaction context. 
146    * 
147    * @param context - An EntityContext interface for the instance. The instance should 
148    *              store the reference to the context in an instance variable. 
149    * @exception EJBException  Thrown by the method to indicate a failure 
150    *                          caused by a system-level error.
151    * @exception RemoteException - This exception is defined in the method signature
152    *                           to provide backward compatibility for enterprise beans
153    *                           written for the EJB 1.0 specification. 
154    *                           Enterprise beans written for the EJB 1.1 and 
155    *                           higher specification should throw the javax.ejb.EJBException 
156    *                           instead of this exception. 
157    */
158   public void setEntityContext(EntityContext context) throws RemoteException
159   {
160     entityContext = context;
161   }
162 
163   /**
164    * Unsets the associated entity context. The container calls this method 
165    *  before removing the instance. This is the last method that the container 
166    *  invokes on the instance. The Java garbage collector will eventually invoke 
167    *  the finalize() method on the instance. 
168    *
169    * This method is called in an unspecified transaction context. 
170    * 
171    * @exception EJBException  Thrown by the method to indicate a failure 
172    *                          caused by a system-level error.
173    * @exception RemoteException - This exception is defined in the method signature
174    *                           to provide backward compatibility for enterprise beans
175    *                           written for the EJB 1.0 specification. 
176    *                           Enterprise beans written for the EJB 1.1 and 
177    *                           higher specification should throw the javax.ejb.EJBException 
178    *                           instead of this exception.
179    */
180   public void unsetEntityContext() throws RemoteException
181   {
182     entityContext = null;
183   }
184 
185   /**
186    * Display category information for the BrowseCategories servlet
187    *
188    * @return a <code>String</code> containing HTML code
189    * @exception RemoteException if an error occurs
190    * @since 1.0
191    */
192   public String   printCategory() throws RemoteException
193   {
194     return "<a HREF=\""+BeanConfig.context+"/servlet/edu.rice.rubis.beans.servlets.SearchItemsByCategory?category="+id+
195                   "&categoryName="+URLEncoder.encode(name)+"\">"+name+"</a><br>\n";
196   }
197 
198   /**
199    * Display category information for the BrowseCategories servlet
200    *
201    * @return a <code>String</code> containing HTML code
202    * @exception RemoteException if an error occurs
203    * @since 1.0
204    */
205   public String   printCategoryByRegion(int regionId) throws RemoteException
206   {
207     return "<a HREF=\""+BeanConfig.context+"/servlet/edu.rice.rubis.beans.servlets.SearchItemsByRegion?category="+id+
208       "&categoryName="+URLEncoder.encode(name)+"&region="+regionId+"\">"+name+"</a><br>\n";
209   }
210 
211 
212   /**
213    * Returns true if the beans has been modified.
214    * It prevents the EJB server from reloading a bean
215    * that has not been modified.
216    *
217    * @return a <code>boolean</code> value
218    */
219   public boolean isModified() 
220   {
221     return isDirty;
222   }
223 
224 
225   /**
226    * Display category information for the BrowseCategories servlet
227    *
228    * @return a <code>String</code> containing HTML code
229    * @exception RemoteException if an error occurs
230    * @since 1.0
231    */
232   public String   printCategoryToSellItem(int userId) throws RemoteException
233   {
234     return "<a HREF=\""+BeanConfig.context+"/servlet/edu.rice.rubis.beans.servlets.SellItemForm?category="+id+"&user="+userId+"\">"+name+"</a><br>\n";
235   }
236 }
237
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