The FileDataSource class implements a simple DataSource object
that encapsulates a file. It provides data typing services via
a FileTypeMap object.
FileDataSource Typing Semantics
The FileDataSource class delegates data typing of files
to an object subclassed from the FileTypeMap class.
The setFileTypeMap
method can be used to explicitly
set the FileTypeMap for an instance of FileDataSource. If no
FileTypeMap is set, the FileDataSource will call the FileTypeMap's
getDefaultFileTypeMap method to get the System's default FileTypeMap.