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Java > Open Source Codes > com > quadcap > sql > MultiCursor


1 package com.quadcap.sql;
2
3 /* Copyright 1999 - 2003 Quadcap Software. All rights reserved.
4  *
5  * This software is distributed under the Quadcap Free Software License.
6  * This software may be used or modified for any purpose, personal or
7  * commercial. Open Source redistributions are permitted. Commercial
8  * redistribution of larger works derived from, or works which bundle
9  * this software requires a "Commercial Redistribution License"; see
10  * http://www.quadcap.com/purchase.
11  *
12  * Redistributions qualify as "Open Source" under one of the following terms:
13  *
14  * Redistributions are made at no charge beyond the reasonable cost of
15  * materials and delivery.
16  *
17  * Redistributions are accompanied by a copy of the Source Code or by an
18  * irrevocable offer to provide a copy of the Source Code for up to three
19  * years at the cost of materials and delivery. Such redistributions
20  * must allow further use, modification, and redistribution of the Source
21  * Code under substantially the same terms as this license.
22  *
23  * Redistributions of source code must retain the copyright notices as they
24  * appear in each source code file, these license terms, and the
25  * disclaimer/limitation of liability set forth as paragraph 6 below.
26  *
27  * Redistributions in binary form must reproduce this Copyright Notice,
28  * these license terms, and the disclaimer/limitation of liability set
29  * forth as paragraph 6 below, in the documentation and/or other materials
30  * provided with the distribution.
31  *
32  * The Software is provided on an "AS IS" basis. No warranty is
33  * provided that the Software is free of defects, or fit for a
34  * particular purpose.
35  *
36  * Limitation of Liability. Quadcap Software shall not be liable
37  * for any damages suffered by the Licensee or any third party resulting
38  * from use of the Software.
39  */
40
41 import java.sql.SQLException JavaDoc;
42
43 import java.util.ArrayList JavaDoc;
44
45 import com.quadcap.util.Debug;
46
47 /**
48  * Cursor implementation that concatenates multiple cursors together and
49  * makes them appear as a single cursor.
50  *
51  * @author Stan Bailes
52  */
53 public class MultiCursor extends FilterCursor {
54     ArrayList JavaDoc cursors = new ArrayList JavaDoc();
55     int cursorNum = 0;
56
57     public MultiCursor(Session session) throws SQLException JavaDoc {
58         super(session);
59     }
60     
61     public MultiCursor(Session session, Cursor cursor) throws SQLException JavaDoc {
62     super(session, cursor);
63     appendCursor(session, cursor);
64     }
65
66     public void appendCursor(Session session, Cursor cursor) throws SQLException JavaDoc {
67     cursors.add(cursor);
68         if (this.cursor == null) {
69             this.cursor = cursor;
70             addColumns(session, cursor);
71         }
72     }
73
74     public void beforeFirst() throws SQLException JavaDoc {
75         for (int i = 0; i < cursors.size(); i++) {
76             Cursor c = ((Cursor)cursors.get(i));
77             c.beforeFirst();
78             if (i == 0) cursor = c;
79         }
80         cursorNum = 0;
81     }
82
83     public boolean next() throws SQLException JavaDoc {
84     boolean ret = cursor.next();
85     while (!ret && ++cursorNum < cursors.size()) {
86         cursor = (Cursor)cursors.get(cursorNum);
87             cursor.beforeFirst();
88         ret = cursor.next();
89     }
90     return ret;
91     }
92
93     public boolean prev() throws SQLException JavaDoc {
94         throw new SQLException JavaDoc("MultiCursor.prev() not implemented");
95     }
96
97     public void close() throws SQLException JavaDoc {
98         for (int i = 0; i < cursors.size(); i++) {
99             try {
100                 ((Cursor)cursors.get(i)).close();
101             } catch (Throwable JavaDoc t) {}
102         }
103     }
104 }
105
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