How Can I extract the .dat file(contain image) using java API

HMEFContentsExtractor ext = new HMEFContentsExtractor(new File(winmailFilename));

   File dir = new File(directoryName);
   File rtf = new File(dir, "message.rtf");
   if(! dir.exists()) {
       throw new FileNotFoundException("Output directory " + dir.getName() + " not found");
   }
   HMEFMessage msg = new HMEFMessage(new FileInputStream(winmailFilename));
   msg.getAttachments();