How can I parse out points and draw a route on a Google Map in Android?

Question

How do I get points & draw the route on Google maps in Android OS?

Answer 1

An example URL you're going to parse is...

http://maps.googleapis.com/maps/api/directions/xml?origin=52.31,16.71&destination=51.27,6.75&sensor=false

change origin [lat,long] and destination[lat, long] for your purpose

--

points fetching

import java.io.StringReader; import java.util.ArrayList; import org.xmlpull.v1.XmlPullParser; import org.xmlpull.v1.XmlPullParserFactory; import net.gynsoft.citydusseldorf.lib.HttpClient; import android.os.Handler; import com.google.android.maps.GeoPoint;   public class MapRoute  { private GeoPoint gpSrc = null; private GeoPoint gpDest = null; private ArrayList<GeoPoint> alRoute = new ArrayList<GeoPoint>(); private Handler haRoute = new Handler();  public interface RouteListener {     public void onDetermined(ArrayList<GeoPoint> alPoint);     public void onError(); }  private RouteListener oRoute = null;   public MapRoute(GeoPoint gpSrc,GeoPoint gpDest) {     this.gpSrc = gpSrc;     this.gpDest = gpDest; }  public void getPoints(RouteListener oRoute) {     this.oRoute = oRoute;     new Thread(ruFetch).start(); }  private Runnable ruFetchOk = new Runnable() {     public void run()     {         oRoute.onDetermined(alRoute);     } };  private Runnable ruFetchError = new Runnable() {     public void run()     {         oRoute.onDetermined(alRoute);     } };  private Runnable ruFetch = new Runnable() {     public void run()     {         String szUrl = "http://maps.googleapis.com/maps/api/directions/xml";         szUrl += "?origin=" + (gpSrc.getLatitudeE6()/1e6) + "," + (gpSrc.getLongitudeE6()/1e6);         szUrl += "&destination=" + (gpDest.getLatitudeE6()/1e6) + "," + (gpDest.getLongitudeE6()/1e6);         szUrl += "&sensor=true";          HttpClient oHttp = HttpClient.getInstance();         String szXml = oHttp.doGet(szUrl,"");          try         {             XmlPullParserFactory xppfFactory = XmlPullParserFactory.newInstance();             xppfFactory.setNamespaceAware(true);             XmlPullParser xppParses = xppfFactory.newPullParser();              xppParses.setInput(new StringReader(szXml));             int iEventType = xppParses.getEventType();             String szTag = "";             String szText = "";             boolean bStep = false;             int iLat = 0;             int iLong = 0;              while(iEventType != XmlPullParser.END_DOCUMENT)              {                       iEventType = xppParses.next();                   if(iEventType == XmlPullParser.START_TAG)                   {                      szTag = xppParses.getName();                       if(szTag.equals("step"))                          bStep = true;                  }                  else if(iEventType == XmlPullParser.TEXT)                        {                        if(szTag.equals("points"))                          szText = "";                      else                          szText = xppParses.getText().trim();                  }                            else if(iEventType == XmlPullParser.END_TAG)                   {                      if(xppParses.getName().equals("step"))                      {                          bStep = false;                      }                     else if(bStep && xppParses.getName().equals("start_location") || xppParses.getName().equals("end_location"))                      {                          GeoPoint gpPoint = new GeoPoint(iLat,iLong);                          alRoute.add(gpPoint);                      }                      else if(bStep && xppParses.getName().equals("lat"))                      {                          iLat = (int)(Double.parseDouble(szText) * 1e6);                      }                      else if(bStep && xppParses.getName().equals("lng"))                      {                          iLong = (int)(Double.parseDouble(szText) * 1e6);                      }                  }             }         }         catch(Exception e)         {             e.printStackTrace();             haRoute.post(ruFetchError);         }           if(alRoute.size() == 0)             haRoute.post(ruFetchError);         else             haRoute.post(ruFetchOk);     } }; } 

--

map overlay

public class MapRouteOverlay extends Overlay  { private GeoPoint gp1; private GeoPoint gp2;  private int mode=0; private int defaultColor;  public MapRouteOverlay(GeoPoint gp1,GeoPoint gp2,int mode) // GeoPoint is a int. (6E) { this.gp1 = gp1; this.gp2 = gp2; this.mode = mode; defaultColor = 999; // no defaultColor  }  public MapRouteOverlay(GeoPoint gp1,GeoPoint gp2,int mode, int defaultColor) { this.gp1 = gp1; this.gp2 = gp2; this.mode = mode; this.defaultColor = defaultColor; }  public int getMode() { return mode; }  public boolean draw (Canvas canvas, MapView mapView, boolean shadow, long when) {     Projection projection = mapView.getProjection();     if (shadow == false)     {          Paint paint = new Paint();         paint.setAntiAlias(true);         paint.setDither(true);         Point point = new Point();         projection.toPixels(gp1, point);          if(mode==2)         {             if(defaultColor==999)             {                 paint.setColor(Color.RED);             }             else             {                 paint.setColor(defaultColor);                 Point point2 = new Point();                 projection.toPixels(gp2, point2);                 paint.setStrokeWidth(5);                 paint.setAlpha(120);                 canvas.drawLine(point.x, point.y, point2.x,point2.y, paint);             }         }     }     return super.draw(canvas, mapView, shadow, when); } } 

--

how to use it... somewhere in my activity

dEmpty = new BitmapDrawable(Bitmap.createBitmap(1,1,Bitmap.Config.ARGB_8888)); dPin = getResources().getDrawable(R.drawable.pin_map);  private void doDrawPath(GeoPoint gpSrc,GeoPoint gpDest)  {     MapRoute oRoute = new MapRoute(gpSrc,gpDest);     oRoute.getPoints(new RouteListener()     {         @Override         public void onDetermined(ArrayList<GeoPoint> alPoint)          {             GeoPoint oPointA = null;             GeoPoint oPointB = null;              mvMap.getOverlays().clear();              for(int i=1; i<alPoint.size()-1; i++)             {                 oPointA = alPoint.get(i-1);                 oPointB =  alPoint.get(i);                  mvMap.getOverlays().add(new MapRouteOverlay(oPointA,oPointB,2,Color.RED));             }               mvMap.getOverlays().add(new MapRoutePinOverlay(alPoint.get(0),dPin));             mvMap.getOverlays().add(new MapRoutePinOverlay(alPoint.get(alPoint.size()-1),dPin));              mvMap.invalidate();         }          @Override         public void onError()          {         }                }); }