It's not truly constant -- at least not if you're using a recent Java 6
Plug-In.
Rather as with Internet Explorer it occurs once per Windows login --
unless you neglect to check the checkbox in the authentication dialog to
request that the credentials be remembered.
In Firefox 3, you didn't have to do this -- the Plug-In just got the
credentials from the browser somehow. As of Firefox 4, however, Firefox
seems to be in the same boat as Internet Explorer here.
I have already filed an enhancement request with Oracle asking for a
Java Control Panel setting to remember the credentials indefinitely
rather than solely for the current Windows login. There's no telling
if/when they'll provide such an enhancement, though.
