public DALObject() {
        try {
            if (cnx == null) {
                System.out.println("Test de connexion au driver JDBC");
                Class.forName("com.mysql.jdbc.Driver");
                System.out.println("Driver O.K.");
                try {
                    System.out.println("Test de connexion à la BDD");
                    url = "jdbc:mysql://localhost/jsimdb";
                    username = "root";
                    password = "";
                    cnx = DriverManager.getConnection(url, username, password);
                    System.out.println("BDD O.K.");
                } catch (SQLException e) {
                    // Si connexion BDD K.O.
                    System.out.println("SQLException: " + e.getMessage()); 
                    System.out.println("SQLState: " + e.getSQLState()); 
                    System.out.println("VendorError: " + e.getErrorCode()); 
                }
            }
            else {
                System.out.println("Une connexion est déjà ouverte");
            }
        } catch (Exception ex) { 
              // Si connexion driver K.O.
              System.out.println("Chargement du driver K.O.");
          }
    }