Connection conn = null;

        Statement stmt = null;

        ResultSet rset = null;

        try {

            conn = dataSource.getConnection();

            stmt = conn.createStatement();

            rset = stmt.executeQuery("select 1 from dual");

        } catch (SQLException e) {

            e.printStackTrace();

        } finally {

             try { if (rset != null) rset.close(); } catch(Exception e) { }

             try { if (stmt != null) stmt.close(); } catch(Exception e) { }

             try { if (conn != null) conn.close(); } catch(Exception e) { }

        }