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public interface FilteredRowSet
Disabled: no SafeJ information.
The standard interface that all standard implementations of
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
TM 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.
In the example above, we initialize a
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
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.
Field Summary |
---|
Fields inherited from interface javax.sql.rowset.WebRowSet |
---|
PUBLIC_XML_SCHEMA, SCHEMA_SYSTEM_ID |
Fields inherited from interface javax.sql.rowset.CachedRowSet |
---|
COMMIT_ON_ACCEPT_CHANGES |
Fields inherited from interface java.sql.ResultSet |
---|
CLOSE_CURSORS_AT_COMMIT, CONCUR_READ_ONLY, CONCUR_UPDATABLE, FETCH_FORWARD, FETCH_REVERSE, FETCH_UNKNOWN, HOLD_CURSORS_OVER_COMMIT, TYPE_FORWARD_ONLY, TYPE_SCROLL_INSENSITIVE, TYPE_SCROLL_SENSITIVE |
Method Summary | |
---|---|
Predicate |
getFilter()
Retrieves the active filter for this FilteredRowSet object. |
void |
setFilter(Predicate p)
Applies the given Predicate object to this
FilteredRowSet
object. |
Methods inherited from interface javax.sql.rowset.WebRowSet |
---|
readXml, readXml, writeXml, writeXml, writeXml, writeXml |
Methods inherited from interface javax.sql.rowset.CachedRowSet |
---|
acceptChanges, acceptChanges, columnUpdated, columnUpdated, commit, createCopy, createCopyNoConstraints, createCopySchema, createShared, execute, getKeyColumns, getOriginal, getOriginalRow, getPageSize, getRowSetWarnings, getShowDeleted, getSyncProvider, getTableName, nextPage, populate, populate, previousPage, release, restoreOriginal, rollback, rollback, rowSetPopulated, setKeyColumns, setMetaData, setOriginalRow, setPageSize, setShowDeleted, setSyncProvider, setTableName, size, toCollection, toCollection, toCollection, undoDelete, undoInsert, undoUpdate |
Methods inherited from interface java.sql.Wrapper |
---|
isWrapperFor, unwrap |
Methods inherited from interface javax.sql.rowset.Joinable |
---|
getMatchColumnIndexes, getMatchColumnNames, setMatchColumn, setMatchColumn, setMatchColumn, setMatchColumn, unsetMatchColumn, unsetMatchColumn, unsetMatchColumn, unsetMatchColumn |
Method Detail |
---|
void setFilter(Predicate p) throws SQLException
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.
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.
SQLException
- if an error occurs when setting the
Predicate
objectPredicate getFilter()
FilteredRowSet
object.
Predicate
for this FilteredRowSet
object; null
if no filter has been set.
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