First of all we will get source and destination points between which we have to draw route. Then we will pass these attribute to below function.
public String makeURL (double sourcelat, double sourcelog, double destlat, double destlog ){
StringBuilder urlString = new StringBuilder();
urlString.append("http://maps.googleapis.com/maps/api/directions/json");
urlString.append("?origin=");// from
urlString.append(Double.toString(sourcelat));
urlString.append(",");
urlString.append(Double.toString( sourcelog));
urlString.append("&destination=");// to
urlString.append(Double.toString( destlat));
urlString.append(",");
urlString.append(Double.toString( destlog));
urlString.append("&sensor=false&mode=driving&alternatives=true");
urlString.append("&key=YOUR_API_KEY");
return urlString.toString();
}
This function will make the url that we will send to get Direction API response. Then we will parse that response . The parser class is
public class JSONParser {
static InputStream is = null;
static JSONObject jObj = null;
static String json = "";
// constructor
public JSONParser() {
}
public String getJSONFromUrl(String url) {
// Making HTTP request
try {
// defaultHttpClient
DefaultHttpClient httpClient = new DefaultHttpClient();
HttpPost httpPost = new HttpPost(url);
HttpResponse httpResponse = httpClient.execute(httpPost);
HttpEntity httpEntity = httpResponse.getEntity();
is = httpEntity.getContent();
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
} catch (ClientProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
try {
BufferedReader reader = new BufferedReader(new InputStreamReader(
is, "iso-8859-1"), 8);
StringBuilder sb = new StringBuilder();
String line = null;
while ((line = reader.readLine()) != null) {
sb.append(line + "
");
}
json = sb.toString();
is.close();
} catch (Exception e) {
Log.e("Buffer Error", "Error converting result " + e.toString());
}
return json;
}
}
This parser will return us string. We will call it like that.
JSONParser jParser = new JSONParser();
String json = jParser.getJSONFromUrl(url);
Now we will send this string to our drawpath function. The drawpath function is
public void drawPath(String result) {
try {
//Tranform the string into a json object
final JSONObject json = new JSONObject(result);
JSONArray routeArray = json.getJSONArray("routes");
JSONObject routes = routeArray.getJSONObject(0);
JSONObject overviewPolylines = routes.getJSONObject("overview_polyline");
String encodedString = overviewPolylines.getString("points");
List<LatLng> list = decodePoly(encodedString);
Polyline line = mMap.addPolyline(new PolylineOptions()
.addAll(list)
.width(12)
.color(Color.parseColor("#05b1fb"))//Google maps blue color
.geodesic(true)
);
/*
for(int z = 0; z<list.size()-1;z++){
LatLng src= list.get(z);
LatLng dest= list.get(z+1);
Polyline line = mMap.addPolyline(new PolylineOptions()
.add(new LatLng(src.latitude, src.longitude), new LatLng(dest.latitude, dest.longitude))
.width(2)
.color(Color.BLUE).geodesic(true));
}
*/
}
catch (JSONException e) {
}
}
Above code will draw the path on mMap. The code of decodePoly is
private List<LatLng> decodePoly(String encoded) {
List<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( (((double) lat / 1E5)),
(((double) lng / 1E5) ));
poly.add(p);
}
return poly;
}
As direction call may take time so we will do all this in Asynchronous task.
My Asynchronous task was
private class connectAsyncTask extends AsyncTask<Void, Void, String>{
private ProgressDialog progressDialog;
String url;
connectAsyncTask(String urlPass){
url = urlPass;
}
@Override
protected void onPreExecute() {
// TODO Auto-generated method stub
super.onPreExecute();
progressDialog = new ProgressDialog(MainActivity.this);
progressDialog.setMessage("Fetching route, Please wait...");
progressDialog.setIndeterminate(true);
progressDialog.show();
}
@Override
protected String doInBackground(Void... params) {
JSONParser jParser = new JSONParser();
String json = jParser.getJSONFromUrl(url);
return json;
}
@Override
protected void onPostExecute(String result) {
super.onPostExecute(result);
progressDialog.hide();
if(result!=null){
drawPath(result);
}
}
}
I hope it will help.
