import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import javax.swing.JOptionPane;

public abstract class DBConnection {
    private static Connection conn = null;
    public static Connection getInstance() {
        if(conn == null){
            try {
                Class.forName("com.mysql.jdbc.Driver");
                System.out.println("Driver O.K.");
                String url = "jdbc:mysql://localhost/nom_de_la_bd";
                String user = "root";
                String passwd = "";
                conn = DriverManager.getConnection(url, user, passwd);
                System.out.println("Connexion effective !");

            } catch (ClassNotFoundException | SQLException e) {
                JOptionPane.showMessageDialog(null, "Erreur de communication avec la base de données!");
            }
        }
        return conn;
    }
}