public SelectLockingStrategy(Lockable lockable,
    LockMode lockMode) 
{
		this.lockable = lockable;
		this.lockMode = lockMode;
		this.sql = generateLockString();
}

Construct a locking strategy based on SQL SELECT statements.

Parameters:

lockable - The metadata for the entity to be locked.

lockMode - Indictates the type of lock to be acquired.

 protected String generateLockString() 
{
		SessionFactoryImplementor factory = lockable.getFactory();
		SimpleSelect select = new SimpleSelect( factory.getDialect() )
				.setLockMode( lockMode )
				.setTableName( lockable.getRootTableName() )
				.addColumn( lockable.getRootTableIdentifierColumnNames()[0] )
				.addCondition( lockable.getRootTableIdentifierColumnNames(), "=?" );
		if ( lockable.isVersioned() ) {
			select.addCondition( lockable.getVersionColumnName(), "=?" );
		}
		if ( factory.getSettings().isCommentsEnabled() ) {
			select.setComment( lockMode + " lock " + lockable.getEntityName() );
		}
		return select.toStatementString();
}

 protected LockMode getLockMode() 
{
		return lockMode;
}

 public  void lock(Serializable id,
    Object version,
    Object object,
    SessionImplementor session) throws StaleObjectStateException, JDBCException 
{
		SessionFactoryImplementor factory = session.getFactory();
		try {
			PreparedStatement st = session.getBatcher().prepareSelectStatement( sql );
			try {
				lockable.getIdentifierType().nullSafeSet( st, id, 1, session );
				if ( lockable.isVersioned() ) {
					lockable.getVersionType().nullSafeSet(
							st,
							version,
							lockable.getIdentifierType().getColumnSpan( factory ) + 1,
							session
					);
				}
				ResultSet rs = st.executeQuery();
				try {
					if ( !rs.next() ) {
						if ( factory.getStatistics().isStatisticsEnabled() ) {
							factory.getStatisticsImplementor()
									.optimisticFailure( lockable.getEntityName() );
						}
						throw new StaleObjectStateException( lockable.getEntityName(), id );
					}
				}
				finally {
					rs.close();
				}
			}
			finally {
				session.getBatcher().closeStatement( st );
			}
		}
		catch ( SQLException sqle ) {
			throw JDBCExceptionHelper.convert(
					session.getFactory().getSQLExceptionConverter(),
					sqle,
					"could not lock: " + MessageHelper.infoString( lockable, id, session.getFactory() ),
					sql
				);
		}
}