Cómo dibujar las direcciones de carreteras entre dos geocódigos en android google map v2?

Cree una clase llamada "DirectionsJSONParser"

public class DirectionsJSONParser { public List<List<HashMap<String,String>>> parse(JSONObject jObject){ List<List<HashMap<String, String>>> routes = new ArrayList<List<HashMap<String,String>>>() ; JSONArray jRoutes = null; JSONArray jLegs = null; JSONArray jSteps = null; try { jRoutes = jObject.getJSONArray("routes"); for(int i=0;i<jRoutes.length();i++){ jLegs = ( (JSONObject)jRoutes.get(i)).getJSONArray("legs"); List path = new ArrayList<HashMap<String, String>>(); for(int j=0;j<jLegs.length();j++){ jSteps = ( (JSONObject)jLegs.get(j)).getJSONArray("steps"); for(int k=0;k<jSteps.length();k++){ String polyline = ""; polyline = (String)((JSONObject)((JSONObject)jSteps.get(k)).get("polyline")).get("points"); List<LatLng> list = decodePoly(polyline); for(int l=0;l<list.size();l++){ HashMap<String, String> hm = new HashMap<String, String>(); hm.put("lat", Double.toString(((LatLng)list.get(l)).latitude) ); hm.put("lng", Double.toString(((LatLng)list.get(l)).longitude) ); path.add(hm); } } routes.add(path); } } } catch (JSONException e) { e.printStackTrace(); }catch (Exception e){ } return routes; } 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; }} 

En la actividad principal

 public class MainActivity extends FragmentActivity { GoogleMap map; ArrayList<LatLng> markerPoints; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); // Initializing array List markerPoints = new ArrayList<LatLng>(); // Getting reference to SupportMapFragment of the activity_main SupportMapFragment fm = (SupportMapFragment)getSupportFragmentManager().findFragmentById(R.id.map); // Getting Map for the SupportMapFragment map = fm.getMap(); map.setMyLocationEnabled(true); map.setOnMapClickListener(new OnMapClickListener() { @Override public void onMapClick(LatLng point) { if(markerPoints.size()>1){ markerPoints.clear(); map.clear(); } markerPoints.add(point); MarkerOptions options = new MarkerOptions(); options.position(point); if(markerPoints.size()==1){ options.icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_GREEN)); }else if(markerPoints.size()==2){ options.icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_RED)); } map.addMarker(options); if(markerPoints.size() >= 2){ LatLng origin = markerPoints.get(0); LatLng dest = markerPoints.get(1); String url = getDirectionsUrl(origin, dest); DownloadTask downloadTask = new DownloadTask(); downloadTask.execute(url); } } }); } private String getDirectionsUrl(LatLng origin,LatLng dest){ // Origin of route String str_origin = "origin="+origin.latitude+","+origin.longitude; // Destination of route String str_dest = "destination="+dest.latitude+","+dest.longitude; // Sensor enabled String sensor = "sensor=false"; // Building the parameters to the web service String parameters = str_origin+"&"+str_dest+"&"+sensor; // Output format String output = "json"; String url = "https://maps.googleapis.com/maps/api/directions/"+output+"?"+parameters; return url; } private String downloadUrl(String strUrl) throws IOException{ String data = ""; InputStream iStream = null; HttpURLConnection urlConnection = null; try{ URL url = new URL(strUrl); urlConnection = (HttpURLConnection) url.openConnection(); // Connecting to url urlConnection.connect(); // Reading data from url iStream = urlConnection.getInputStream(); BufferedReader br = new BufferedReader(new InputStreamReader(iStream)); StringBuffer sb = new StringBuffer(); String line = ""; while( ( line = br.readLine()) != null){ sb.append(line); } data = sb.toString(); br.close(); }catch(Exception e){ Log.d("Exception while downloading url", e.toString()); }finally{ iStream.close(); urlConnection.disconnect(); } return data; } // Fetches data from url passed private class DownloadTask extends AsyncTask<String, Void, String>{ // Downloading data in non-ui thread @Override protected String doInBackground(String... url) { // For storing data from web service String data = ""; try{ // Fetching the data from web service data = downloadUrl(url[0]); }catch(Exception e){ Log.d("Background Task",e.toString()); } return data; } // Executes in UI thread, after the execution of // doInBackground() @Override protected void onPostExecute(String result) { super.onPostExecute(result); ParserTask parserTask = new ParserTask(); // Invokes the thread for parsing the JSON data parserTask.execute(result); } } private class ParserTask extends AsyncTask<String, Integer, List<List<HashMap<String,String>>> { @Override protected List<List<HashMap<String, String>>> doInBackground(String... jsonData) { JSONObject jObject; List<List<HashMap<String, String>>> routes = null; try{ jObject = new JSONObject(jsonData[0]); DirectionsJSONParser parser = new DirectionsJSONParser(); // Starts parsing data routes = parser.parse(jObject); }catch(Exception e){ e.printStackTrace(); } return routes; } @Override protected void onPostExecute(List<List<HashMap<String, String>>> result) { ArrayList<LatLng> points = null; PolylineOptions lineOptions = null; MarkerOptions markerOptions = new MarkerOptions(); // Traversing through all the routes for(int i=0;i<result.size();i++){ points = new ArrayList<LatLng>(); lineOptions = new PolylineOptions(); // Fetching i-th route List<HashMap<String, String>> path = result.get(i); // Fetching all the points in i-th route for(int j=0;j<path.size();j++){ HashMap<String,String> point = path.get(j); double lat = Double.parseDouble(point.get("lat")); double lng = Double.parseDouble(point.get("lng")); LatLng position = new LatLng(lat, lng); points.add(position); } // Adding all the points in the route to LineOptions lineOptions.addAll(points); lineOptions.width(2); lineOptions.color(Color.RED); } // Drawing polyline in the Google Map for the i-th route map.addPolyline(lineOptions); } } @Override public boolean onCreateOptionsMenu(Menu menu) { // Inflate the menu; this adds items to the action bar if it is present. getMenuInflater().inflate(R.menu.main, menu); return true; }} 

Puede utilizar esta función para mostrar la dirección en Google NavigationApp preinstalado

  public void showDirections(double lat, double lng, double lat1, double lng1) { final Intent intent = new Intent(Intent.ACTION_VIEW, Uri.parse("http://maps.google.com/maps?" + "saddr=" + lat + "," + lng + "&daddr=" + lat1 + "," + lng1)); intent.setClassName("com.google.android.apps.maps", "com.google.android.maps.MapsActivity"); startActivity(intent); }