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Java > Open Source Codes > org > apache > struts > webapp > example2 > UserDatabase


1 /*
2  * Copyright 1999-2002,2004 The Apache Software Foundation.
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  * http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16
17
18 package org.apache.struts.webapp.example2;
19
20
21 /**
22  * <p>A <strong>Data Access Object</strong> (DAO) interface describing
23  * the available operations for retrieving and storing {@link User}s
24  * (and their associated {@link Subscription}s) in some persistence layer
25  * whose characteristics are not specified here. One or more implementations
26  * will be created to perform the actual I/O that is required.</p>
27  *
28  * @author Craig R. McClanahan
29  * @version $Rev: 54934 $ $Date: 2004-10-16 18:07:50 +0100 (Sat, 16 Oct 2004) $
30  * @since Struts 1.1
31  */
32
33 public interface UserDatabase {
34
35
36     // --------------------------------------------------------- Public Methods
37
38
39     /**
40      * <p>Create and return a new {@link User} defined in this user database.
41      * </p>
42      *
43      * @param username Username of the new user
44      *
45      * @exception IllegalArgumentExceptionif the specified username
46      * is not unique
47      */
48     public User createUser(String JavaDoc username);
49
50
51     /**
52      * <p>Finalize access to the underlying persistence layer.</p>
53      *
54      * @exception Exception if a database access error occurs
55      */
56     public void close() throws Exception JavaDoc;
57
58
59     /**
60      * <p>Return the existing {@link User} with the specified username,
61      * if any; otherwise return <code>null</code>.</p>
62      *
63      * @param username Username of the user to retrieve
64      */
65     public User findUser(String JavaDoc username);
66
67
68     /**
69      * <p>Return the set of {@link User}s defined in this user database.</p>
70      */
71     public User[] findUsers();
72
73
74     /**
75      * <p>Initiate access to the underlying persistence layer.</p>
76      *
77      * @exception Exception if a database access error occurs
78      */
79     public void open() throws Exception JavaDoc;
80
81
82     /**
83      * Remove the specified {@link User} from this database.
84      *
85      * @param user User to be removed
86      *
87      * @exception IllegalArgumentException if the specified user is not
88      * associated with this database
89      */
90     public void removeUser(User user);
91
92
93     /**
94      * <p>Save any pending changes to the underlying persistence layer.</p>
95      *
96      * @exception Exception if a database access error occurs
97      */
98     public void save() throws Exception JavaDoc;
99
100
101 }
102
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