best way to keep a datasource static in tomcat servlet app

Question

I have a web APP in tomcat 8 with servlets tecnology. For DB connection I have a servlet listener that keep a static datasource and a static method that do a getConnection. All run fine in the serlvet I can call to servletListener.getConnection();

But inside classes can't call it.

I found this class in internet:

public final class DBUtilClass {
    private static DataSource datasource;

    static {
        Context initContext;
        try {
            initContext = new InitialContext();
            Context envContext = (Context) initContext.lookup("java:/comp/env");
            datasource = (DataSource) envContext.lookup("jdbc/testdb");
        } catch (NamingException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

    public static Connection getConnection() throws SQLException {
        return datasource.getConnection();
    }

I like it because i can call it from all classes. I am not sure if it is the best way.

others aproach? Any recomendations?