public interface: Wrapper
All Known Implementing Classes:
FilteredRowSet, DataSource, JdbcRowSet, CachedRowSet, CallableStatement, DatabaseMetaData, SyncResolver, RowSetMetaDataImpl, JoinRowSet, ResultSetMetaData, PreparedStatement, ParameterMetaData, ResultSet, RowSetMetaData, RowSet, Statement, Connection, WebRowSet
Interface for JDBC classes which provide the ability to retrieve the delegate instance when the instance
in question is in fact a proxy class.
The wrapper pattern is employed by many JDBC driver implementations to provide extensions beyond
the traditional JDBC API that are specific to a data source. Developers may wish to gain access to
these resources that are wrapped (the delegates) as proxy class instances representing the
the actual resources. This interface describes a standard mechanism to access
these wrapped resources
represented by their proxy, to permit direct access to the resource delegates.
|Method from java.sql.Wrapper Detail:|
public boolean isWrapperFor(Class<?> iface) throws SQLException
Returns true if this either implements the interface argument or is directly or indirectly a wrapper
for an object that does. Returns false otherwise. If this implements the interface then return true,
else if this is a wrapper then return the result of recursively calling
isWrapperFor on the wrapped
object. If this does not implement the interface and is not a wrapper, return false.
This method should be implemented as a low-cost operation compared to
unwrap so that
callers can use this method to avoid expensive
unwrap calls that may fail. If this method
returns true then calling
unwrap with the same argument should succeed.
public T unwrap(Class<T> iface) throws SQLException
Returns an object that implements the given interface to allow access to
non-standard methods, or standard methods not exposed by the proxy.
If the receiver implements the interface then the result is the receiver
or a proxy for the receiver. If the receiver is a wrapper
and the wrapped object implements the interface then the result is the
wrapped object or a proxy for the wrapped object. Otherwise return the
the result of calling
unwrap recursively on the wrapped object
or a proxy for that result. If the receiver is not a
wrapper and does not implement the interface, then an
SQLException is thrown.