1 /*
2 * Copyright (c) 2003, 2013, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package javax.sql.rowset;
27
28 import java.sql.*;
29 import javax.sql.*;
30 import javax.naming.*;
31 import java.io.*;
32 import java.math.*;
33
34 /**
35 * The standard interface that all standard implementations of
36 * <code>FilteredRowSet</code> must implement. The <code>FilteredRowSetImpl</code> class
37 * provides the reference implementation which may be extended if required.
38 * Alternatively, a vendor is free to implement its own version
39 * by implementing this interface.
40 *
41 * <h3>1.0 Background</h3>
42 *
43 * There are occasions when a <code>RowSet</code> object has a need to provide a degree
44 * of filtering to its contents. One possible solution is to provide
45 * a query language for all standard <code>RowSet</code> implementations; however,
46 * this is an impractical approach for lightweight components such as disconnected
47 * <code>RowSet</code>
48 * objects. The <code>FilteredRowSet</code> interface seeks to address this need
49 * without supplying a heavyweight query language along with the processing that
50 * such a query language would require.
51 * <p>
52 * A JDBC <code>FilteredRowSet</code> standard implementation implements the
53 * <code>RowSet</code> interfaces and extends the
54 * <code>CachedRowSet</code>™ class. The
55 * <code>CachedRowSet</code> class provides a set of protected cursor manipulation
56 * methods, which a <code>FilteredRowSet</code> implementation can override
57 * to supply filtering support.
58 *
59 * <h3>2.0 Predicate Sharing</h3>
60 *
61 * If a <code>FilteredRowSet</code> implementation is shared using the
62 * inherited <code>createShared</code> method in parent interfaces, the
63 * <code>Predicate</code> should be shared without modification by all
64 * <code>FilteredRowSet</code> instance clones.
65 *
66 * <h3>3.0 Usage</h3>
67 * <p>
68 * By implementing a <code>Predicate</code> (see example in <a href="Predicate.html">Predicate</a>
69 * class JavaDoc), a <code>FilteredRowSet</code> could then be used as described
70 * below.
71 *
72 * <pre>
73 * {@code
74 * FilteredRowSet frs = new FilteredRowSetImpl();
75 * frs.populate(rs);
76 *
77 * Range name = new Range("Alpha", "Bravo", "columnName");
78 * frs.setFilter(name);
79 *
80 * frs.next() // only names from "Alpha" to "Bravo" will be returned
81 * }
82 * </pre>
83 * In the example above, we initialize a <code>Range</code> object which
84 * implements the <code>Predicate</code> interface. This object expresses
85 * the following constraints: All rows outputted or modified from this
86 * <code>FilteredRowSet</code> object must fall between the values 'Alpha' and
87 * 'Bravo' both values inclusive, in the column 'columnName'. If a filter is
88 * applied to a <code>FilteredRowSet</code> object that contains no data that
89 * falls within the range of the filter, no rows are returned.
90 * <p>
91 * This framework allows multiple classes implementing predicates to be
92 * used in combination to achieved the required filtering result with
93 * out the need for query language processing.
94 *
95 * <h3>4.0 Updating a <code>FilteredRowSet</code> Object</h3>
96 * The predicate set on a <code>FilteredRowSet</code> object
97 * applies a criterion on all rows in a
98 * <code>RowSet</code> object to manage a subset of rows in a <code>RowSet</code>
99 * object. This criterion governs the subset of rows that are visible and also
100 * defines which rows can be modified, deleted or inserted.
101 * <p>
102 * Therefore, the predicate set on a <code>FilteredRowSet</code> object must be
103 * considered as bi-directional and the set criterion as the gating mechanism
104 * for all views and updates to the <code>FilteredRowSet</code> object. Any attempt
105 * to update the <code>FilteredRowSet</code> that violates the criterion will
106 * result in a <code>SQLException</code> object being thrown.
107 * <p>
108 * The <code>FilteredRowSet</code> range criterion can be modified by applying
109 * a new <code>Predicate</code> object to the <code>FilteredRowSet</code>
110 * instance at any time. This is possible if no additional references to the
111 * <code>FilteredRowSet</code> object are detected. A new filter has has an
112 * immediate effect on criterion enforcement within the
113 * <code>FilteredRowSet</code> object, and all subsequent views and updates will be
114 * subject to similar enforcement.
115 *
116 * <h3>5.0 Behavior of Rows Outside the Filter</h3>
117 * Rows that fall outside of the filter set on a <code>FilteredRowSet</code>
118 * object cannot be modified until the filter is removed or a
119 * new filter is applied.
120 * <p>
121 * Furthermore, only rows that fall within the bounds of a filter will be
122 * synchronized with the data source.
123 *
124 * @author Jonathan Bruce
125 */
126
127 public interface FilteredRowSet extends WebRowSet {
128
129 /**
130 * Applies the given <code>Predicate</code> object to this
131 * <code>FilteredRowSet</code>
132 * object. The filter applies controls both to inbound and outbound views,
133 * constraining which rows are visible and which
134 * rows can be manipulated.
135 * <p>
136 * A new <code>Predicate</code> object may be set at any time. This has the
137 * effect of changing constraints on the <code>RowSet</code> object's data.
138 * In addition, modifying the filter at runtime presents issues whereby
139 * multiple components may be operating on one <code>FilteredRowSet</code> object.
140 * Application developers must take responsibility for managing multiple handles
141 * to <code>FilteredRowSet</code> objects when their underling <code>Predicate</code>
142 * objects change.
143 *
144 * @param p a <code>Predicate</code> object defining the filter for this
145 * <code>FilteredRowSet</code> object. Setting a <b>null</b> value
146 * will clear the predicate, allowing all rows to become visible.
147 *
148 * @throws SQLException if an error occurs when setting the
149 * <code>Predicate</code> object
150 */
151 public void setFilter(Predicate p) throws SQLException;
152
153 /**
154 * Retrieves the active filter for this <code>FilteredRowSet</code> object.
155 *
156 * @return p the <code>Predicate</code> for this <code>FilteredRowSet</code>
157 * object; <code>null</code> if no filter has been set.
158 */
159 public Predicate getFilter() ;
160 }