This implementation caches every file as long as it is strongly reachable by
the java vm. As soon as the object is no longer reachable it will be discarded.
In contrast to the SoftRefFilesCache this implementation might free resources faster
as it don't wait until a memory limitation.
author: Mario Ivankovits version: $Revision: 485638 $ $Date: 2005-09-30 09:02:41 +0200 (Fr, 30 Sep version: 2005) $ See Also:java.lang.ref.WeakReference