@Override
 public void close(Connection conn) {
   try {
     ConnectionManagerJdbc.getInstance(config).close(conn);
   } catch (SQLException se) {
     String message = "failed to close connection.";
     logger.warn(message);
   }
 }
 @Override
 public void rollback(Connection conn) {
   if (logger.isDebugEnabled()) {
     logger.debug(String.format("rollback(conn=%s) - start ", conn));
   }
   try {
     ConnectionManagerJdbc.getInstance(config).rollback(conn);
   } catch (SQLException se) {
     String message = "failed to rollback connection.";
     logger.warn(message);
   }
   if (logger.isDebugEnabled()) {
     logger.debug("rollback() - end ");
   }
 }
 @Override
 public void commit(Connection conn) throws SQLException {
   ConnectionManagerJdbc.getInstance(config).commit(conn);
 }
 @Override
 public Connection getConnection(boolean autoCommit) throws SQLException {
   Connection conn = ConnectionManagerJdbc.getInstance(config).getConnection();
   conn.setAutoCommit(autoCommit);
   return conn;
 }