FilteredRowSet must implement. The FilteredRowSetImpl 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.
*
* RowSet 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 RowSet implementations; however,
* this is an impractical approach for lightweight components such as disconnected
* RowSet
* objects. The FilteredRowSet interface seeks to address this need
* without supplying a heavyweight query language along with the processing that
* such a query language would require.
*
* A JDBC FilteredRowSet standard implementation implements the
* RowSet interfaces and extends the
* CachedRowSet™ class. The
* CachedRowSet class provides a set of protected cursor manipulation
* methods, which a FilteredRowSet implementation can override
* to supply filtering support.
*
*
FilteredRowSet implementation is shared using the
* inherited createShared method in parent interfaces, the
* Predicate should be shared without modification by all
* FilteredRowSet instance clones.
*
*
* By implementing a Predicate (see example in Predicate
* class JavaDoc), a FilteredRowSet could then be used as described
* below.
*
*
* {@code
* 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
* }
*
* In the example above, we initialize a Range object which
* implements the Predicate interface. This object expresses
* the following constraints: All rows outputted or modified from this
* FilteredRowSet object must fall between the values 'Alpha' and
* 'Bravo' both values inclusive, in the column 'columnName'. If a filter is
* applied to a FilteredRowSet object that contains no data that
* falls within the range of the filter, no rows are returned.
* * 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. * *
FilteredRowSet ObjectFilteredRowSet object
* applies a criterion on all rows in a
* RowSet object to manage a subset of rows in a RowSet
* object. This criterion governs the subset of rows that are visible and also
* defines which rows can be modified, deleted or inserted.
*
* Therefore, the predicate set on a FilteredRowSet object must be
* considered as bi-directional and the set criterion as the gating mechanism
* for all views and updates to the FilteredRowSet object. Any attempt
* to update the FilteredRowSet that violates the criterion will
* result in a SQLException object being thrown.
*
* The FilteredRowSet range criterion can be modified by applying
* a new Predicate object to the FilteredRowSet
* instance at any time. This is possible if no additional references to the
* FilteredRowSet object are detected. A new filter has has an
* immediate effect on criterion enforcement within the
* FilteredRowSet object, and all subsequent views and updates will be
* subject to similar enforcement.
*
*
FilteredRowSet
* object cannot be modified until the filter is removed or a
* new filter is applied.
*
* Furthermore, only rows that fall within the bounds of a filter will be
* synchronized with the data source.
*
* @author Jonathan Bruce
* @since 1.5
*/
public interface FilteredRowSet extends WebRowSet {
/**
* Applies the given Predicate object to this
* FilteredRowSet
* object. The filter applies controls both to inbound and outbound views,
* constraining which rows are visible and which
* rows can be manipulated.
*
* A new Predicate object may be set at any time. This has the
* effect of changing constraints on the RowSet object's data.
* In addition, modifying the filter at runtime presents issues whereby
* multiple components may be operating on one FilteredRowSet object.
* Application developers must take responsibility for managing multiple handles
* to FilteredRowSet objects when their underling Predicate
* objects change.
*
* @param p a Predicate object defining the filter for this
* FilteredRowSet object. Setting a null value
* will clear the predicate, allowing all rows to become visible.
*
* @throws SQLException if an error occurs when setting the
* Predicate object
*/
public void setFilter(Predicate p) throws SQLException;
/**
* Retrieves the active filter for this FilteredRowSet object.
*
* @return p the Predicate for this FilteredRowSet
* object; null if no filter has been set.
*/
public Predicate getFilter() ;
}