This implementation caches every file as long as it is strongly reachable by
the java vm. As soon as the vm needs memory - every softly reachable file
will be discarded.
author: Mario Ivankovits version: $Revision: 551086 $ $Date: 2005-09-30 09:02:41 +0200 (Fr, 30 Sep version: 2005) $ See Also:SoftReference