java – Connection error sql remote communications link Failure g cloud

Hello at all I try to connect through a server Tomcat hosted on google cloud to my host DB (Green Geek) I have donats created two rule firewall between /out on google is one on GreenGreek for the sql Distant cepandant after multiple attempt the system answers me:
Communications link failure The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
I attach my java ee code

private Connection appelBD(String dataBase, String user, String motDePasse) {
    Connection connection = null;

    try {
    } catch (ClassNotFoundException e1) {

        modelI18n = new ModelI18n();

    try {
        connection = DriverManager.getConnection("jdbc:mysql://" + dataBase, user, motDePasse);
         * MysqlDataSource ds = new MysqlDataSource(); ds.setDatabaseName(dataBase);
         * ds.setUser(user); ds.setPassword(motDePasse);
         * ds.setServerName(""); ds.setServerTimezone("UTC");
         * ds.setPort(3306);
        return connection;
    } catch (Exception e) {

        modelI18n2 = new ModelI18n();

        return null;

would have leads to help me thank you in advance