private static String formatSentence(Position position) {
StringBuilder s = new StringBuilder("$GPRMC,");
try (Formatter f = new Formatter(s, Locale.ENGLISH)) {
Calendar calendar = Calendar.getInstance(TimeZone.getTimeZone("UTC"), Locale.ENGLISH);
calendar.setTimeInMillis(position.getFixTime().getTime());
f.format("%1$tH%1$tM%1$tS.%1$tL,A,", calendar);
double lat = position.getLatitude();
double lon = position.getLongitude();
f.format("%02d%07.4f,%c,", (int) Math.abs(lat), Math.abs(lat) % 1 * 60, lat < 0 ? 'S' : 'N');
f.format("%03d%07.4f,%c,", (int) Math.abs(lon), Math.abs(lon) % 1 * 60, lon < 0 ? 'W' : 'E');
f.format("%.2f,%.2f,", position.getSpeed(), position.getCourse());
f.format("%1$td%1$tm%1$ty,,", calendar);
}
s.append(Checksum.nmea(s.toString()));
return s.toString();
}
@Override
protected Object decode(Channel channel, SocketAddress remoteAddress, Object msg)
throws Exception {
ChannelBuffer buf = (ChannelBuffer) msg;
buf.skipBytes(2); // header
buf.readUnsignedShort(); // length
String imei = ChannelBuffers.hexDump(buf.readBytes(7));
if (!identify(imei, channel, null, false)
&& !identify(imei + Checksum.luhn(Long.parseLong(imei)), channel)) {
return null;
}
int type = buf.readUnsignedShort();
if (type == MSG_LOCATION_REPORT || type == MSG_LOCATION_REQUEST) {
String sentence =
buf.toString(buf.readerIndex(), buf.readableBytes() - 8, Charset.defaultCharset());
Parser parser = new Parser(PATTERN, sentence);
if (!parser.matches()) {
return null;
}
Position position = new Position();
position.setProtocol(getProtocolName());
position.setDeviceId(getDeviceId());
if (parser.hasNext(15)) {
DateBuilder dateBuilder =
new DateBuilder()
.setDate(parser.nextInt(), parser.nextInt(), parser.nextInt())
.setTime(parser.nextInt(), parser.nextInt(), parser.nextInt());
position.setTime(dateBuilder.getDate());
position.setValid(parser.next().equals("A"));
position.set(Event.KEY_SATELLITES, parser.next());
position.setLatitude(parser.nextCoordinate(Parser.CoordinateFormat.HEM_DEG));
position.setLongitude(parser.nextCoordinate(Parser.CoordinateFormat.HEM_DEG));
position.setSpeed(parser.nextDouble());
position.set(Event.KEY_HDOP, parser.nextDouble());
position.setAltitude(parser.nextDouble());
} else {
getLastLocation(position, null);
}
position.set(Event.KEY_MCC, parser.nextInt());
position.set(Event.KEY_MNC, parser.nextInt());
position.set(Event.KEY_LAC, parser.nextInt());
position.set(Event.KEY_CELL, parser.nextInt());
return position;
}
return null;
}
private static boolean validateImei(long imei) {
return Checksum.luhn(imei / 10) == imei % 10;
}