问题
I am drawing a route between two points in a map. I receive the points this way:
StringBuilder urlString = new StringBuilder();
urlString.append("http://maps.googleapis.com/maps/api/directions/json");
urlString.append("?origin=");// from
urlString.append(Double.toString(src.latitude));
urlString.append(",");
urlString.append(Double.toString(src.longitude));
urlString.append("&destination=");// to
urlString.append(Double.toString(dest.latitude));
urlString.append(",");
urlString.append(Double.toString(dest.longitude));
urlString.append("&sensor=false&mode=");
if (tipo != null) {
urlString.append(tipo);
}
return urlString.toString;
I receive the response from Google, and get the JSON:
resp = new JSONObject(builder.toString());
Log.i("Location", "Contenido del kml: "+resp);
JSONArray routeObject = resp.getJSONArray("routes");
JSONObject routes = routeObject.getJSONObject(0);
JSONObject overviewPolylines = routes
.getJSONObject("overview_polyline");
String encodedString = overviewPolylines.getString("points");
ArrayList<LatLng> puntos=decodePoly(encodedString);
The response I get from google: (in JSON format):
Response: {"status":"OK","routes":[{"waypoint_order":[],"summary":"R-3 and A-3","bounds":{"southwest":{"lng":-3.676540000000001,"lat":40.00040000000001},"northeast":{"lng":-2.99933,"lat":40.43357}},"legs":[{"duration":{"value":3267,"text":"54 mins"},"distance":{"value":85039,"text":"85.0 km"},"end_location":{"lng":-2.99933,"lat":40.00040000000001},"start_address":"Calle del General Díaz Porlier, 91, 28006 Madrid, Spain","end_address":"Camino Veinticuatro, 2, 16400 Tarancón, Cuenca, Spain","start_location":{"lng":-3.676540000000001,"lat":40.43331000000001},"via_waypoint":[],"steps":[{"html_instructions":"Head <b>north<\/b> on <b>Calle del Gral Díaz Porlier<\/b> toward <b>Calle de Maldonado<\/b>","duration":{"value":6,"text":"1 min"},"distance":{"value":29,"text":"29 m"},"end_location":{"lng":-3.676520000000001,"lat":40.43357},"polyline":{"points":"ecxuFjamUs@C"},"travel_mode":"DRIVING","start_location":{"lng":-3.676540000000001,"lat":40.43331000000001}},{"html_instructions":"Take the 1st <b>right<\/b> onto <b>Calle de Maldonado<\/b>","duration":{"value":62,"text":"1 min"},"distance":{"value":266,"text":"0.3 km"},"end_location":{"lng":-3.6734,"lat":40.43345},"polyline":{"points":"ydxuFfamUPkG@a@JuGGk@"},"travel_mode":"DRIVING","start_location":{"lng":-3.676520000000001,"lat":40.43357}},{"html_instructions":"Take the 2nd <b>right<\/b> onto <b>Calle de Fco. Silvela<\/b>","duration":{"value":57,"text":"1 min"},"distance":{"value":245,"text":"0.2 km"},"end_location":{"lng":-3.671830000000001,"lat":40.4316},"polyline":{"points":"adxuFvmlURQl@e@zAoATSTMf@]pBeBLK"},"travel_mode":"DRIVING","start_location":{"lng":-3.6734,"lat":40.43345}},{"html_instructions":"Slight <b>right<\/b> onto <b>Calle de Francisco Silvela<\/b>","duration":{"value":51,"text":"1 min"},"distance":{"value":437,"text":"0.4 km"},"end_location":{"lng":-3.66913,"lat":40.42827},"polyline":{"points":"oxwuF|clUJADAFCbBkAjAeA`BoA^[XUPMLMFEnAeALIdBuAZUPMXS"},"travel_mode":"DRIVING","start_location":{"lng":-3.671830000000001,"lat":40.4316}},{"html_instructions":"Turn <b>right<\/b> onto <b>Pl. de Manuel Becerra<\/b>","duration":{"value":32,"text":"1 min"},"distance":{"value":154,"text":"0.2 km"},"end_location":{"lng":-3.668380000000001,"lat":40.42827},"polyline":{"points":"ucwuF`skU@?@@@@@?@@@?FBD?F@FAFAFADEDCFGDGDIBI@I@K@KAI?IAGAGAGCGCC?ACEEEIGGEICI?I?G@IBGD"},"travel_mode":"DRIVING","start_location":{"lng":-3.66913,"lat":40.42827}},{"html_instructions":"Turn <b>right<\/b> onto <b>Calle Alcala<\/b>","duration":{"value":61,"text":"1 min"},"distance":{"value":709,"text":"0.7 km"},"end_location":{"lng":-3.66107,"lat":40.43126000000001},"polyline":{"points":"ucwuFjnkUo@}A_AcCiEeLKYq@mBYq@[o@u@kB?KAQ]aAI[EQQu@Gc@QwAM_BEa@AU"},"travel_mode":"DRIVING","start_location":{"lng":-3.668380000000001,"lat":40.42827}},{"html_instructions":"Turn <b>right<\/b> onto the ramp to <b>M-30\/A-3\/A-4<\/b>","duration":{"value":44,"text":"1 min"},"distance":{"value":453,"text":"0.5 km"},"end_location":{"lng":-3.660580000000001,"lat":40.42720000000001},"polyline":{"points":"kvwuFt`jU\\CjIg@nBKD?rCOvDY"},"travel_mode":"DRIVING","start_location":{"lng":-3.66107,"lat":40.43126000000001}},{"html_instructions":"Continue straight","duration":{"value":45,"text":"1 min"},"distance":{"value":1009,"text":"1.0 km"},"end_location":{"lng":-3.659120000000001,"lat":40.41822000000001},"polyline":{"points":"_}vuFr}iUzKgBvCe@t@KvGm@hDUbAMPCZElAM|D_@^En@EjBEd@Df@DnAD"},"travel_mode":"DRIVING","start_location":{"lng":-3.660580000000001,"lat":40.42720000000001}},{"html_instructions":"Take exit <b>7B<\/b> to merge onto <b>M-23<\/b> toward <b>Vicálvaro\/R-3\/Valencia<\/b>","duration":{"value":117,"text":"2 mins"},"distance":{"value":2552,"text":"2.6 km"},"end_location":{"lng":-3.63392,"lat":40.41499},"polyline":{"points":"{duuFntiUFHB@^PDBFFFDDFDFBDDFBH@BBJ@F@H?F@H?FAH?FAF?FADAFAFCDADADEFCFEDEDEDEBEBEBGBE@G@E@G?G?EAG?GCGAGCEEGEEEEEEGEICIEIAKCKAK?K?MDgA?G?E?KJq@BODY@CBODW?C@I@AFe@F_@V{An@gED[@C?EHe@Ho@@G?A^{BjA}HF[tAiGzBwIdAcEVgApAuFr@sEF]Ju@DW?EDUHa@f@qEFo@f@iGXmHDgFCgGG{DM
And finally, i decode the received String this way, wich I found in plenty of answers here in Stackoverflow:
private ArrayList<LatLng> decodePoly(String encoded) {
Log.i("Location", "String received: "+encoded);
ArrayList<LatLng> poly = new ArrayList<LatLng>();
int index = 0, len = encoded.length();
int lat = 0, lng = 0;
while (index < len) {
int b, shift = 0, result = 0;
do {
b = encoded.charAt(index++) - 63;
result |= (b & 0x1f) << shift;
shift += 5;
} while (b >= 0x20);
int dlat = ((result & 1) != 0 ? ~(result >> 1) : (result >> 1));
lat += dlat;
shift = 0;
result = 0;
do {
b = encoded.charAt(index++) - 63;
result |= (b & 0x1f) << shift;
shift += 5;
} while (b >= 0x20);
int dlng = ((result & 1) != 0 ? ~(result >> 1) : (result >> 1));
lng += dlng;
LatLng p = new LatLng((int) (((double) lat /1E5)* 1E6), (int) (((double) lng/1E5 * 1E6)));
poly.add(p);
}
for(int i=0;i<poly.size();i++){
Log.i("Location", "Point sent: Latitude: "+poly.get(i).latitude+" Longitude: "+poly.get(i).longitude);
}
return poly;
}
This is where I think the error is, because I set a for to see the points that are being decoded, and the answer is something like:
04-10 13:33:54.578: I/Location(25065): Point sent: Latitude: 90.0 Longitude: -110.0
04-10 13:33:54.578: I/Location(25065): Point sent: Latitude: 90.0 Longitude: -120.0
04-10 13:33:54.578: I/Location(25065): Point sent: Latitude: 90.0 Longitude: 100.0
04-10 13:33:54.578: I/Location(25065): Point sent: Latitude: 90.0 Longitude: 120.0
04-10 13:33:54.578: I/Location(25065): Point sent: Latitude: 90.0 Longitude: 40.0
Obviosly, these points are badly parsed. The result is, no line drawn anywhere.
My question is... anybody knows how to parse the answer from Google, and translate it to LatLng objects (NOT GeoPoints Objects)?
Thank you!
EDIT:
This is the String that is about to be decoded:
04-10 13:50:51.608: I/Location(25065): String to decode: gcxuFjamUq@CPkGLwHJ}@hCuBdEeDf@SrJuHnG{Ed@Fr@q@AmAm@k@e@DaIaSiEuLqAwJ~Mw@~ZwDtZuC`FKbCVjA`ANdAs@nBw@Py@]c@oAT}DhC{PlBcM~GaY|DyS`BmPRy]yBu\UsNvAqObAuEnC}KpAqIh@gK[}NcByWXoRt@}GlDeWvFcq@nFi`@~G}\|@aDdDoLn`@}gAfe@upA`JyV|CiN~@uId@{ZyBwVkBmOwB{^AsNt@iWb@qYcCyS_DkPmAaK{@gRN{RbCkWrFgUbHmPxLsP|JwIpPwN|G}JfE}I|C_KlCsNvAwSFaQj@i]jCmXbHg\pIgSpGaLnN}P`JsHfVaNbQkHtZyIrOsCnTaCx\aA`i@b@nSRz]K`J{AxJiDfNkJjU{WbKkJpGeEpVkPpEiEzMcQjQw]nJyM~IoJ`IoKnH{NrOaWtIeJdNgNrLcPjKqOhIuI~MeJxKgErR{Cn]EjQkBjHqBfJeE|\yTlI_JvEqJxHsS|Xuc@~IeR|EiRr@kEz@sNOoL_B}Lk@mCsFgKkCoGwAsG]}N`CuO`D}GjHoHtFwC|HgBhFg@fJ}BtHaF~D_FjLqSfGqE|FcBnGEnEv@xK`BzNeAxQfAlJ{@jIwEjE}FvBuF|B{NtCsNrBgEdHiIdGuIxDoFpGkFhDaBrHyBbF[pHPlDg@jEuBnCkCtFgKjEqEfIcGpC{D|GoNdAcExAkSjBgDrCsBpDa@vHLfSAfBk@nE_F|Im`@tO_ZxCyEzJmKtHyElG_ClZeF|j@sIlQaD|EuChGkHnK{MdIsMfPwa@bDeJpD_RpFsz@nA}IrCqIrYoa@|BeGlEiYpD}HbKoRfCyKdBwUjEmo@zBkKzDyJvCeQdB}LJqGmAqQJ_Gx@uFtHkO`ImMfMmXtFySpCkXRuN]aYVoT~@}LxB{NvD{OjJaYbFsLnCcEtLoMfJyXzIiXbIiL~D_EzQcMjDeF|AcFhA_M`BkXpC_KjCsDnDeClQcHvEgElFqJfF_Jp\mWzd@k]`WkWlVy`@nOcTz`@_s@rP_ZbNkQ~Tu^jJaUhCuIpHgUrPi\zd@uq@~McQh\e]vTaU~KcF~KoGhG{KzF{HzGmDbDwBfDiEzB}GbEmTrBsHpCuFxe@oq@xb@el@tDgC`ZeJnXkHrKmB~EeB~C{A`Ce@bCUrBoAnAuGSqIn@yEhDeOrCuQ|A}EvAwFdDgAfGSrHUJ\p@Bj@_A|Ao@tCsD|C}Rj@wAdCuW~Ds]VCJw@OUpEc_@jDKbDwB
If with LatLng formate you mean the way the LatLng objects are created, you can see in the decodePoly method. These latLng objects are added to the PolylineOptions objects, and the this added to the map, this way:
PolylineOption ruta=new PolylineOptions();
for(int i=0;i<puntos.size();i++){
ruta.add(new LatLng(puntos.get(i).latitude, puntos.get(i).longitude));
}//puntos is an array where the array returned by the decodePoly method are stored
ruta.color(Color.RED).width(7);
Polyline polygon=mapa.addPolyline(ruta);
回答1:
I changed the decodePoly that I was using for this one I found after a long search in Google, and now the route is drawn properly.
http://wptrafficanalyzer.in/blog/route-between-two-locations-with-waypoints-in-google-map-android-api-v2/
Changing
LatLng p = new LatLng((int) (((double) lat /1E5)* 1E6), (int) (((double) lng/1E5 * 1E6)));
for
LatLng p = new LatLng((((double) lat / 1E5)),(((double) lng / 1E5)));
And now works.
回答2:
For those who need this now, there's an open-source library with a lot of useful stuff regarding the Google Maps Android API, including decoding and encoding of polylines.
Check it out at Android Maps Utils and Android Maps Util Github. For decoding and encoding use:
PolyUtil.decode(String encodedPath);
PolyUtil.encode(List<LatLng> path);
回答3:
Same in Javascript
function decodePolyline(encoded) {
if (!encoded) {
return [];
}
var poly = [];
var index = 0, len = encoded.length;
var lat = 0, lng = 0;
while (index < len) {
var b, shift = 0, result = 0;
do {
b = encoded.charCodeAt(index++) - 63;
result = result | ((b & 0x1f) << shift);
shift += 5;
} while (b >= 0x20);
var dlat = (result & 1) != 0 ? ~(result >> 1) : (result >> 1);
lat += dlat;
shift = 0;
result = 0;
do {
b = encoded.charCodeAt(index++) - 63;
result = result | ((b & 0x1f) << shift);
shift += 5;
} while (b >= 0x20);
var dlng = (result & 1) != 0 ? ~(result >> 1) : (result >> 1);
lng += dlng;
var p = {
latitude: lat / 1e5,
longitude: lng / 1e5,
};
poly.push(p);
}
return poly;
}
回答4:
This method is useful for decoding polyline
private List<LatLng> decodePoly(String encoded) {
List<LatLng> poly = new ArrayList<>();
int index = 0, len = encoded.length();
int lat = 0, lng = 0;
while (index < len) {
int b, shift = 0, result = 0;
do {
b = encoded.charAt(index++) - 63;
result |= (b & 0x1f) << shift;
shift += 5;
} while (b >= 0x20);
int dlat = ((result & 1) != 0 ? ~(result >> 1) : (result >> 1));
lat += dlat;
shift = 0;
result = 0;
do {
b = encoded.charAt(index++) - 63;
result |= (b & 0x1f) << shift;
shift += 5;
} while (b >= 0x20);
int dlng = ((result & 1) != 0 ? ~(result >> 1) : (result >> 1));
lng += dlng;
LatLng p = new LatLng((((double) lat / 1E5)),
(((double) lng / 1E5)));
poly.add(p);
}
return poly;
}
This is how i'm getting polyline
JSONObject poly = route.getJSONObject("overview_polyline");
String polyline = poly.getString("points");
polyLineList = decodePoly(polyline);
回答5:
Same in Pascal (Delphi):
function DecodeLine(inputstring: String): String;
var
lat, lon, lat_f, lon_f: Double;
index: Integer;
len: Integer;
b: Integer;
shift: Integer;
decodeResult: Integer;
encoded: String;
dlat: Integer;
dlng: Integer;
begin
Result := '';
encoded := inputstring;
len := Length(encoded);
index := 1;
lat := 0;
lon := 0;
while (index <= len) do begin
b := $20;
shift := 0;
decodeResult := 0;
while (b >= $20) do begin
b := ord(encoded[index]);
b := b - 63;
inc(index);
decodeResult := decodeResult or (b and $1f) Shl shift;
shift := shift + 5;
end;
if (decodeResult and 1) <> 0 then
dlat := not (decodeResult shr 1)
else
dlat := decodeResult shr 1;
lat := lat+dlat;
shift := 0;
decodeResult := 0;
b := $20;
while (b >= $20) do begin
b := ord(encoded[index]);
b := b-63;
inc(index);
decodeResult := decodeResult or (b and $1f) Shl shift;
shift := shift + 5;
end;
if (decodeResult and 1) <> 0 then
dlng := not (decodeResult shr 1)
else
dlng := decodeResult shr 1;
lon := lon + dlng;
{ The coordinates of the point are used for our purposes }
lon_f := lon/100000.0;
lat_f := lat/100000.0;
if Result <> '' then
Result := Result + ', ';
Result := Result + '(' + FloatToStr(lon_f) + ' - ' + FloatToStr(lat_f) + ')';
end; //while
end;
procedure TForm1.Button1Click(Sender: TObject);
var
str: String;
begin
// Do stuff
str := DecodeLine('ibgqGq}ycIMvM');
ShowMessage(str);
end;
回答6:
Here is the implementation in iOS, for anybody who is curious, which is entirely based upon @Fustigador's answer, but converted to iOS. Note that I have not formatted the code accordingly. I only added some variables for the sake of returning the promised object.
- (GMSPath *)decodedPolylinePathFromEncodedPolylineString:(NSString *)encodedPolylineString {
NSString *decodedPolylineString = @"";
GMSMutablePath *decodedPolylinePath = [GMSMutablePath new];
CLLocationCoordinate2D decodedCoordinate;
CLLocationDegrees latitude, longitude;
int index = 0;
NSUInteger len = encodedPolylineString.length;
int lat = 0, lng = 0;
while (index < len) {
int b, shift = 0, result = 0;
do {
b = [encodedPolylineString characterAtIndex:index++] - 63;
result |= (b & 0x1f) << shift;
shift += 5;
} while (b >= 0x20);
int dlat = ((result & 1) != 0 ? ~(result >> 1) : (result >> 1));
lat += dlat;
shift = 0;
result = 0;
do {
b = [encodedPolylineString characterAtIndex:index++] - 63;
result |= (b & 0x1f) << shift;
shift += 5;
} while (b >= 0x20);
int dlng = ((result & 1) != 0 ? ~(result >> 1) : (result >> 1));
lng += dlng;
latitude = (((double) lat / 1E5));
longitude = (((double) lng / 1E5));
decodedCoordinate = CLLocationCoordinate2DMake(latitude, longitude);
decodedPolylineString = [NSString stringWithFormat:@"%f%f", latitude, longitude];
;
NSLog(@"%@",decodedPolylineString);
[decodedPolylinePath addCoordinate:decodedCoordinate];
}
return decodedPolylinePath;
}
来源：https://stackoverflow.com/questions/15924834/decoding-polyline-with-new-google-maps-api