Handling files with the JNLP API requires the use of the following classes:
FileContents. This class represents a file, both for reading and for writing, using the usual input and output streams. It is metered; that is, only a given amount of space (bytes) can be allocated for a file in order to allow JNLP Clients to maintain control on the local resources allocated to launched applications. Note that path information is absent. This means that applications obtaining this object (by means of one of the following three services: FileOpenService, FileSaveService and PersistenceService) can examine only the file contents.
FileOpenService. Applications wanting to access files on the local system should use this service. For untrusted ...