@Stateless
class ShowDB extends AbstractDB {
... 
  public List<BaseModel> getTypesList() {
    List<BaseModel> ret = new ArrayList<>();
    String sql = "SELECT " +
            " s.show_type_id," +
            " s.show_type_name" +
            " FROM gk.t_show_type s";
    PreparedStatement s;
    try {
      s = getConnection().prepareStatement(sql);
      try (ResultSet r = s.executeQuery()) {
        while (r.next()) {
          BaseModel model = new BaseModel();
          model.setId(r.getLong("show_type_id"));
          model.setName(r.getString("show_type_name"));
          ret.add(model);
        }
        r.close();
      } catch (SQLException e) {
        Logger.getLogger(ShowDB.class.getName()).log(Level.SEVERE, "getTypesList:s.executeQuery():", e);
      } finally {
        s.close();
      }
    } catch (SQLException e) {
      Logger.getLogger(ShowDB.class.getName()).log(Level.SEVERE, "getTypesList:conn.prepareStatement():", e);
    }
    return ret;
  }

public abstract class AbstractDB {
  @Resource(name = "jdbc/worker1")
  private DataSource dataSource;
  @Getter(AccessLevel.PROTECTED)
  Connection connection = null;

  @PostConstruct
  private void init() {
    try {
      connection = dataSource.getConnection();
      Logger.getLogger(AbstractDB.class.getName()).log(Level.SEVERE, "init:start db connection!!! ", connection);
    } catch (SQLException e) {
      Logger.getLogger(AbstractDB.class.getName()).log(Level.SEVERE, "init:dataSource.getConnection():", e);
    }
  }

  @PreDestroy
  private void destroy() {
    if (null != connection) {
      try {
        try {
          connection.close();
          connection = null;
        } catch (SQLException e) {
          throw new SQLException("connection.close()" + e.getMessage());
        }
        Logger.getLogger(AbstractDB.class.getName()).log(Level.SEVERE, "destroy:stop db connection!!! ", connection);
      } catch (SQLException e) {
        Logger.getLogger(AbstractDB.class.getName()).log(Level.SEVERE, "destroy:conn.close():", e);
      }
    }
  }
}

#|2013-02-14T13:35:40.309+0400|WARNING|glassfish3.1.2|javax.enterprise.resource.resourceadapter.com.sun.enterprise.resource.pool|_ThreadID=55;_ThreadName=Thread-2;|A potential connection leak detected for connection pool worker1. The stack trace of the thread is provided below : 
db.AbstractDB.init(AbstractDB.java:29)

connection = dataSource.getConnection();

@PreDestroy
  private void destroy() {
    if (null != connection) {
      try {
        try {
          connection.close();
          connection = null;
        } catch (SQLException e) {
          throw new SQLException("connection.close()" + e.getMessage());
        }