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NMEA parser in java which does not suck
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| this software is under the terms of MIT license: http://opensource.org/licenses/MIT |
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| package es.agroguia.model; | |
| import java.util.HashMap; | |
| import java.util.Map; | |
| public class NMEA { | |
| // fucking java interfaces | |
| interface SentenceParser { | |
| public boolean parse(String [] tokens, GPSPosition position); | |
| } | |
| // utils | |
| static float Latitude2Decimal(String lat, String NS) { | |
| try { | |
| float med = Float.parseFloat(lat.substring(2)) / 60.0f; | |
| med += Float.parseFloat(lat.substring(0, 2)); | |
| if (NS.startsWith("S")) { | |
| med = -med; | |
| } | |
| return med; | |
| } | |
| catch(Exception e){ | |
| return 0; | |
| } | |
| } | |
| static float Longitude2Decimal(String lon, String WE) { | |
| try { | |
| float med = Float.parseFloat(lon.substring(3)) / 60.0f; | |
| med += Float.parseFloat(lon.substring(0, 3)); | |
| if (WE.startsWith("W")) { | |
| med = -med; | |
| } | |
| return med; | |
| } | |
| catch(Exception e){ | |
| return 0; | |
| } | |
| } | |
| // parsers | |
| class GPGGA implements SentenceParser { | |
| public boolean parse(String [] tokens, GPSPosition position) { | |
| try { | |
| position.time = Float.parseFloat(tokens[1]); | |
| } | |
| catch(Exception e){} | |
| position.lat = Latitude2Decimal(tokens[2], tokens[3]); | |
| position.lon = Longitude2Decimal(tokens[4], tokens[5]); | |
| try { | |
| position.quality = Integer.parseInt(tokens[6]); | |
| } | |
| catch(Exception e){} | |
| try { | |
| position.altitude = Float.parseFloat(tokens[9]); | |
| } | |
| catch(Exception e){} | |
| return true; | |
| } | |
| } | |
| class GPGGL implements SentenceParser { | |
| public boolean parse(String [] tokens, GPSPosition position) { | |
| position.lat = Latitude2Decimal(tokens[1], tokens[2]); | |
| position.lon = Longitude2Decimal(tokens[3], tokens[4]); | |
| try { | |
| position.time = Float.parseFloat(tokens[5]); | |
| } | |
| catch(Exception e){} | |
| return true; | |
| } | |
| } | |
| class GPRMC implements SentenceParser { | |
| public boolean parse(String [] tokens, GPSPosition position) { | |
| try { | |
| position.time = Float.parseFloat(tokens[1]); | |
| } | |
| catch(Exception e){} | |
| position.lat = Latitude2Decimal(tokens[3], tokens[4]); | |
| position.lon = Longitude2Decimal(tokens[5], tokens[6]); | |
| try { | |
| position.velocity = Float.parseFloat(tokens[7]); | |
| } | |
| catch(Exception e){} | |
| try { | |
| position.dir = Float.parseFloat(tokens[8]); | |
| } | |
| catch(Exception e){} | |
| return true; | |
| } | |
| } | |
| class GPVTG implements SentenceParser { | |
| public boolean parse(String [] tokens, GPSPosition position) { | |
| position.dir = Float.parseFloat(tokens[3]); | |
| return true; | |
| } | |
| } | |
| class GPRMZ implements SentenceParser { | |
| public boolean parse(String [] tokens, GPSPosition position) { | |
| position.altitude = Float.parseFloat(tokens[1]); | |
| return true; | |
| } | |
| } | |
| public class GPSPosition { | |
| public float time = 0.0f; | |
| public float lat = 0.0f; | |
| public float lon = 0.0f; | |
| public boolean fixed = false; | |
| public int quality = 0; | |
| public float dir = 0.0f; | |
| public float altitude = 0.0f; | |
| public float velocity = 0.0f; | |
| public void updatefix() { | |
| fixed = quality > 0; | |
| } | |
| public String toString() { | |
| return String.format("POSITION: lat: %f, lon: %f, time: %f, Q: %d, dir: %f, alt: %f, vel: %f", lat, lon, time, quality, dir, altitude, velocity); | |
| } | |
| } | |
| GPSPosition position = new GPSPosition(); | |
| private static final Map<String, SentenceParser> sentenceParsers = new HashMap<String, SentenceParser>(); | |
| public NMEA() { | |
| sentenceParsers.put("GPGGA", new GPGGA()); | |
| sentenceParsers.put("GPGGL", new GPGGL()); | |
| sentenceParsers.put("GPRMC", new GPRMC()); | |
| sentenceParsers.put("GPRMZ", new GPRMZ()); | |
| //only really good GPS devices have this sentence but ... | |
| sentenceParsers.put("GPVTG", new GPVTG()); | |
| } | |
| public GPSPosition parse(String line) { | |
| if(line.startsWith("$")) { | |
| String nmea = line.substring(1); | |
| String[] tokens = nmea.split(","); | |
| String type = tokens[0]; | |
| //TODO check crc | |
| if(sentenceParsers.containsKey(type)) { | |
| sentenceParsers.get(type).parse(tokens, position); | |
| } | |
| position.updatefix(); | |
| } | |
| return position; | |
| } | |
| } |
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