Well, if the applet is on a password protected page, it implies you will give the password only to people you trust, no?
Actually, it might even be enough to give the URL of your applet only to selected people...
That said, once someone has access to your page, he can easily get the credentials to your database...
Alternatively, a safer way to access database access is to make an intermediary Web API, managed by a server-side script which will have the direct access to the database. Thus, you can ensure, for example, read-only access, limit access to some tables only, and so on.