1 /***
2 * Redistribution and use in source and binary forms, with or without
3 * modification, are permitted provided that the following conditions are
4 * met :
5 *
6 * . Redistributions of source code must retain the above copyright
7 * notice, this list of conditions and the following disclaimer.
8 *
9 * . Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 *
13 * . The name of the author may not be used to endorse or promote products
14 * derived from this software without specific prior written permission.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
18 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
19 * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
20 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
21 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
22 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
24 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
25 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
26 * POSSIBILITY OF SUCH DAMAGE.
27 *
28 * $Id: Resolver.java,v 1.3 2005/08/26 18:09:35 mat007 Exp $
29 */
30
31 package jtge.engine.data;
32
33 import java.util.Hashtable;
34
35 /***
36 * Implements a data identifier resolver.
37 * <p>
38 * This class registers data in order to retrieve them later based on their identifier.
39 *
40 * @author Mathieu Champlon
41 * @version $Revision: 1.3 $ $Date: 2005/08/26 18:09:35 $
42 */
43 public class Resolver implements IResolver
44 {
45 private final Hashtable objects;
46
47 /***
48 * Create a resolver.
49 */
50 public Resolver()
51 {
52 objects = new Hashtable();
53 }
54
55 /***
56 * Register a new data.
57 * <p>
58 * The data cannot be registered if another data with the same identifier already exists.
59 *
60 * @param data the data to register
61 * @return Whether the data has been registered or not
62 */
63 public final boolean register( final IData data )
64 {
65 if( data == null )
66 return false;
67 if( this.objects.containsKey( data.getIdentifier() ) )
68 return false;
69 this.objects.put( data.getIdentifier(), data );
70 return true;
71 }
72
73 /***
74 * Unregister a data.
75 * <p>
76 * The data cannot be unregistered if it has not been previously registered.
77 *
78 * @param data the data to unregister
79 * @return Whether the data has been unregistered or not
80 */
81 public final boolean unregister( final IData data )
82 {
83 if( data == null )
84 return false;
85 return this.objects.remove( data.getIdentifier() ) != null;
86 }
87
88 /***
89 * {@inheritDoc}
90 */
91 public final IData resolve( final String identifier )
92 {
93 return (IData)objects.get( identifier );
94 }
95 }