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Java > Open Source Codes > com > Yasna > forum > database > DbQueryIterator


1 /**
2  * Copyright (C) 2001 Yasna.com. All rights reserved.
3  *
4  * ===================================================================
5  * The Apache Software License, Version 1.1
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  *
11  * 1. Redistributions of source code must retain the above copyright
12  * notice, this list of conditions and the following disclaimer.
13  *
14  * 2. Redistributions in binary form must reproduce the above copyright
15  * notice, this list of conditions and the following disclaimer in
16  * the documentation and/or other materials provided with the
17  * distribution.
18  *
19  * 3. The end-user documentation included with the redistribution,
20  * if any, must include the following acknowledgment:
21  * "This product includes software developed by
22  * Yasna.com (http://www.yasna.com)."
23  * Alternately, this acknowledgment may appear in the software itself,
24  * if and wherever such third-party acknowledgments normally appear.
25  *
26  * 4. The names "Yazd" and "Yasna.com" must not be used to
27  * endorse or promote products derived from this software without
28  * prior written permission. For written permission, please
29  * contact yazd@yasna.com.
30  *
31  * 5. Products derived from this software may not be called "Yazd",
32  * nor may "Yazd" appear in their name, without prior written
33  * permission of Yasna.com.
34  *
35  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
36  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
37  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
38  * DISCLAIMED. IN NO EVENT SHALL YASNA.COM OR
39  * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
40  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
41  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
42  * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
43  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
44  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
45  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
46  * SUCH DAMAGE.
47  * ====================================================================
48  *
49  * This software consists of voluntary contributions made by many
50  * individuals on behalf of Yasna.com. For more information
51  * on Yasna.com, please see <http://www.yasna.com>.
52  */
53
54 /**
55  * Copyright (C) 2000 CoolServlets.com. All rights reserved.
56  *
57  * ===================================================================
58  * The Apache Software License, Version 1.1
59  *
60  * Redistribution and use in source and binary forms, with or without
61  * modification, are permitted provided that the following conditions
62  * are met:
63  *
64  * 1. Redistributions of source code must retain the above copyright
65  * notice, this list of conditions and the following disclaimer.
66  *
67  * 2. Redistributions in binary form must reproduce the above copyright
68  * notice, this list of conditions and the following disclaimer in
69  * the documentation and/or other materials provided with the
70  * distribution.
71  *
72  * 3. The end-user documentation included with the redistribution,
73  * if any, must include the following acknowledgment:
74  * "This product includes software developed by
75  * CoolServlets.com (http://www.coolservlets.com)."
76  * Alternately, this acknowledgment may appear in the software itself,
77  * if and wherever such third-party acknowledgments normally appear.
78  *
79  * 4. The names "Jive" and "CoolServlets.com" must not be used to
80  * endorse or promote products derived from this software without
81  * prior written permission. For written permission, please
82  * contact webmaster@coolservlets.com.
83  *
84  * 5. Products derived from this software may not be called "Jive",
85  * nor may "Jive" appear in their name, without prior written
86  * permission of CoolServlets.com.
87  *
88  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
89  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
90  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
91  * DISCLAIMED. IN NO EVENT SHALL COOLSERVLETS.COM OR
92  * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
93  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
94  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
95  * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
96  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
97  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
98  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
99  * SUCH DAMAGE.
100  * ====================================================================
101  *
102  * This software consists of voluntary contributions made by many
103  * individuals on behalf of CoolServlets.com. For more information
104  * on CoolServlets.com, please see <http://www.coolservlets.com>.
105  */
106
107 package com.Yasna.forum.database;
108
109 import java.util.*;
110
111 import com.Yasna.util.*;
112 import com.Yasna.forum.*;
113
114 /**
115  * Iterator for database query results.
116  */
117 public class DbQueryIterator implements Iterator {
118
119     //maintain an array of message ids to iterator through.
120 private int [] messages;
121     //points to the current message id that the user has iterated to.
122 private int currentIndex = -1;
123
124     private int maxIndex;
125
126     private DbForumFactory factory;
127
128     /**
129      * Creates a new query iterator using an array of message id's. The
130      * ForumFactory is used to lookup the actual message objects.
131      *
132      * @param messages the array of message id's to iterate through.
133      * @param factory a DbForumFactory to obtain actual message objects from.
134      */
135     public DbQueryIterator(int [] messages, DbForumFactory factory) {
136         this.messages = messages;
137         this.factory = factory;
138         maxIndex = messages.length;
139     }
140
141     /**
142      * Creates a new query iterator using an array of message id's. The
143      * ForumFactory is used to lookup the actual message objects. A start index
144      * and number of results limit the scope of the Iterator to a subset of the
145      * message array. However, if the start index or number of results does
146      * not fall into the bounds of the message array, the Iterator may return
147      * fewer results than the number indicated by the numResults paramater.
148      *
149      * @param messages the array of message id's to iterate through.
150      * @param factory a DbForumFactory to obtain actual message objects from.
151      * @param startIndex a starting index in the messages array for the Iterator.
152      * @param numResults the max number of results the Iterator should provide.
153      */
154     public DbQueryIterator(int [] messages, DbForumFactory factory,
155             int startIndex, int numResults)
156     {
157         this.messages = messages;
158         this.factory = factory;
159         currentIndex = startIndex-1;
160         maxIndex = startIndex + numResults;
161     }
162
163     /**
164      * Returns true if there are more messages left to iteratate through.
165      */
166     public boolean hasNext() {
167         return (currentIndex+1 < messages.length && currentIndex+1 < maxIndex);
168     }
169
170     /**
171      * Returns the next message.
172      */
173     public Object JavaDoc next() throws java.util.NoSuchElementException JavaDoc {
174         ForumMessage message = null;
175         currentIndex++;
176         if (currentIndex >= messages.length) {
177             throw new java.util.NoSuchElementException JavaDoc();
178         }
179         try {
180             int messageID = messages[currentIndex];
181             message = factory.getMessage(messageID);
182             //Now, get the message from the it's thread so that filters are
183 //applied to the message. This may seem a bit convuluted, but is
184 //necessary.
185 message = message.getForumThread().getMessage(messageID);
186         }
187         catch (Exception JavaDoc e) {
188             e.printStackTrace();
189         }
190         return message;
191     }
192
193     /**
194      * For security reasons, the remove operation is not supported.
195      */
196     public void remove() {
197         throw new UnsupportedOperationException JavaDoc();
198     }
199 }
200
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