code: public long getSize(String filename)
          throws IOException, ServerException {
          if (filename == null) {
              throw new IllegalArgumentException("Required argument missing");
          }
          Command cmd = new Command("SIZE", filename);
          Reply reply = null;
          try {
              reply = controlChannel.execute(cmd);
              return Long.parseLong(reply.getMessage());
          } catch (NumberFormatException e) {
              throw ServerException.embedFTPReplyParseException(
                           new FTPReplyParseException(
                                  FTPReplyParseException.MESSAGE_UNPARSABLE,
                                 "Could not parse size: " + reply.getMessage()));
          } catch (UnexpectedReplyCodeException urce) {
              throw ServerException.embedUnexpectedReplyCodeException(urce);
          } catch (FTPReplyParseException rpe) {
              throw ServerException.embedFTPReplyParseException(rpe);
          }
      }
docs: Returns the remote file size.
  
  @param     filename filename get the size for.
  @return    size of the file.
  @exception ServerException if the file does not exist or
  an error occured.