if (jar_entry == null) throw new IOException (jar_url + " couldn't be found.");
  public InputStream getInputStream() throws IOException  {    if (!connected)      connect();    if (! doInput)      throw new ProtocolException("Can't open InputStream if doInput is false");        if (jar_entry == null)      throw new IOException (jar_url + " couldn't be found.");        return jar_file.getInputStream (jar_entry);  }