J. Duke | 319a3b9 | 2007-12-01 00:00:00 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 2003-2004 Sun Microsystems, Inc. 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. Sun designates this |
| 8 | * particular file as subject to the "Classpath" exception as provided |
| 9 | * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
| 22 | * CA 95054 USA or visit www.sun.com if you need additional information or |
| 23 | * have any 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><sup><font size=-2>TM</font></sup> 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 | * <P> |
| 72 | * <code> |
| 73 | * <pre> |
| 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 | * </pre> |
| 82 | * </code> |
| 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 | * <p> |
| 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 | * <p> |
| 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 | } |