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/* * @(#)FilteredRowSet.java 1.8 05/11/17 * * Copyright 2006 Sun Microsystems, Inc. All rights reserved. * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms. */ package javax.sql.rowset; import java.sql.*; import javax.sql.*; import javax.naming.*; import java.io.*; import java.math.*; /** * The standard interface that all standard implementations of * <code>FilteredRowSet</code> must implement. The <code>FilteredRowSetImpl</code> class * provides the reference implementation which may be extended if required. * Alternatively, a vendor is free to implement its own version * by implementing this interface. * * <h3>1.0 Background</h3> * * There are occasions when a <code>RowSet</code> object has a need to provide a degree * of filtering to its contents. One possible solution is to provide * a query language for all standard <code>RowSet</code> implementations; however, * this is an impractical approach for lightweight components such as disconnected * <code>RowSet</code> * objects. The <code>FilteredRowSet</code> interface seeks to address this need * without supplying a heavyweight query language along with the processing that * such a query language would require. * <p> * A JDBC <code>FilteredRowSet</code> standard implementation implements the * <code>RowSet</code> interfaces and extends the * <code>CachedRowSet</code><sup><font size=-2>TM</font></sup> class. The * <code>CachedRowSet</code> class provides a set of protected cursor manipulation * methods, which a <code>FilteredRowSet</code> implementation can override * to supply filtering support. * * <h3>2.0 Predicate Sharing</h3> * * If a <code>FilteredRowSet</code> implementation is shared using the * inherited <code>createShared</code> method in parent interfaces, the * <code>Predicate</code> should be shared without modification by all * <code>FilteredRowSet</code> instance clones. * * <h3>3.0 Usage</h3> * <p> * By implementing a <code>Predicate</code> (see example in <a href="Predicate.html">Predicate</a> * class JavaDoc), a <code>FilteredRowSet</code> could then be used as described * below. * <P> * <code> * <pre> * FilteredRowSet frs = new FilteredRowSetImpl(); * frs.populate(rs); * * Range name = new Range("Alpha", "Bravo", "columnName"); * frs.setFilter(name); * * frs.next() // only names from "Alpha" to "Bravo" will be returned * </pre> * </code> * In the example above, we initialize a <code>Range</code> object which * implements the <code>Predicate</code> interface. This object expresses * the following constraints: All rows outputted or modified from this * <code>FilteredRowSet</code> object must fall between the values 'Alpha' and * 'Bravo' both values inclusive, in the column 'columnName'. If a filter is * applied to a <code>FilteredRowSet</code> object that contains no data that * falls within the range of the filter, no rows are returned. * <p> * This framework allows multiple classes implementing predicates to be * used in combination to achieved the required filtering result with * out the need for query language processing. * <p> * <h3>4.0 Updating a <code>FilteredRowSet</code> Object</h3> * The predicate set on a <code>FilteredRowSet</code> object * applies a criterion on all rows in a * <code>RowSet</code> object to manage a subset of rows in a <code>RowSet</code> * object. This criterion governs the subset of rows that are visible and also * defines which rows can be modified, deleted or inserted. * <p> * Therefore, the predicate set on a <code>FilteredRowSet</code> object must be * considered as bi-directional and the set criterion as the gating mechanism * for all views and updates to the <code>FilteredRowSet</code> object. Any attempt * to update the <code>FilteredRowSet</code> that violates the criterion will * result in a <code>SQLException</code> object being thrown. * <p> * The <code>FilteredRowSet</code> range criterion can be modified by applying * a new <code>Predicate</code> object to the <code>FilteredRowSet</code> * instance at any time. This is possible if no additional references to the * <code>FilteredRowSet</code> object are detected. A new filter has has an * immediate effect on criterion enforcement within the * <code>FilteredRowSet</code> object, and all subsequent views and updates will be * subject to similar enforcement. * <p> * <h3>5.0 Behavior of Rows Outside the Filter</h3> * Rows that fall outside of the filter set on a <code>FilteredRowSet</code> * object cannot be modified until the filter is removed or a * new filter is applied. * <p> * Furthermore, only rows that fall within the bounds of a filter will be * synchronized with the data source. * * @author Jonathan Bruce */ public interface FilteredRowSet extends WebRowSet { /** * Applies the given <code>Predicate</code> object to this * <code>FilteredRowSet</code> * object. The filter applies controls both to inbound and outbound views, * constraining which rows are visible and which * rows can be manipulated. * <p> * A new <code>Predicate</code> object may be set at any time. This has the * effect of changing constraints on the <code>RowSet</code> object's data. * In addition, modifying the filter at runtime presents issues whereby * multiple components may be operating on one <code>FilteredRowSet</code> object. * Application developers must take responsibility for managing multiple handles * to <code>FilteredRowSet</code> objects when their underling <code>Predicate</code> * objects change. * * @param p a <code>Predicate</code> object defining the filter for this * <code>FilteredRowSet</code> object. Setting a <b>null</b> value * will clear the predicate, allowing all rows to become visible. * * @throws SQLException if an error occurs when setting the * <code>Predicate</code> object */ public void setFilter(Predicate p) throws SQLException; /** * Retrieves the active filter for this <code>FilteredRowSet</code> object. * * @return p the <code>Predicate</code> for this <code>FilteredRowSet</code> * object; <code>null</code> if no filter has been set. */ public Predicate getFilter() ; }