Set an appropriate NativeJdbcExtractor to be able to retrieve the underlying
native
oracle.jdbc.OracleConnection. This is necessary for
DataSource-based connection pools, as those need to return wrapped JDBC
Connection handles that cannot be cast to a native Connection implementation.
Effectively, this LobHandler just invokes a single NativeJdbcExtractor
method, namely
getNativeConnectionFromStatement with a
PreparedStatement argument (falling back to a
PreparedStatement.getConnection() call if no extractor is set).
A common choice is
SimpleNativeJdbcExtractor, whose Connection unwrapping
(which is what OracleLobHandler needs) will work with many connection pools.
See
SimpleNativeJdbcExtractor and
oracle.jdbc.OracleConnection javadoc for details.