Android implements the method of drawing routes on map

This article gives an example of an Android implementation that draws routes on map. Share to everybody for everybody reference. The details are as follows:

Recently, I was trying to draw the route line on the map. After 1 period of exploration, I finally figured it out. In fact, it is quite simple. For Overaly, to mark a point or draw a line on the map, overlay is used. overlay is equivalent to a overlay on the map. The overlay has to be self-implemented and therefore inherited from Overlay.

MapActivity. java as follows:

package net.blogjava.mobile.map; 
import java.util.List; 
import Android.app.AlertDialog; 
import android.graphics.Bitmap; 
import android.graphics.BitmapFactory; 
import android.graphics.Canvas; 
import android.graphics.Color; 
import android.graphics.Paint; 
import android.graphics.Path; 
import android.graphics.Point; 
import android.location.Address; 
import android.location.Geocoder; 
import android.os.Bundle; 
import android.view.Menu; 
import com.google.android.maps.GeoPoint; 
import com.google.android.maps.MapActivity; 
import com.google.android.maps.MapController; 
import com.google.android.maps.MapView; 
import com.google.android.maps.Overlay; 
import com.google.android.maps.Projection; 
public class Main extends MapActivity { 
private GeoPoint gpoint1, gpoint2, gpoint3;//  Attachment points  
@Override 
public void onCreate(Bundle savedInstanceState) { 
 super.onCreate(savedInstanceState); 
 setContentView(R.layout.main); 
 MapView mapView = (MapView) findViewById(R.id.mapview); 
 mapView.setClickable(true); 
 mapView.setBuiltInZoomControls(true); 
 MapController mapController = mapView.getController(); 
 mapView.setTraffic(true);//  Traffic map  
 // mapView.setSatellite(true);// Satellite imagery  
 // mapView.setStreetView(true);// Street view  
 MyOverlay myOverlay = new MyOverlay(); 
 mapView.getOverlays().add(myOverlay); 
 mapController.setZoom(15);//  Initial magnification  
 gpoint1 = new GeoPoint((int) (24.477384 * 1000000), 
 (int) (118.158216 * 1000000)); 
 gpoint2 = new GeoPoint((int) (24.488967 * 1000000), 
 (int) (118.144277 * 1000000)); 
 gpoint3 = new GeoPoint((int) (24.491091 * 1000000), 
 (int) (118.136781 * 1000000)); 
 mapController.animateTo(gpoint1); 
} 
@Override 
protected boolean isRouteDisplayed() { 
 // TODO Auto-generated method stub 
 return false; 
} 
class MyOverlay extends Overlay { 
 @Override 
 public void draw(Canvas canvas, MapView mapView, boolean shadow) { 
 // TODO Auto-generated method stub 
 super.draw(canvas, mapView, shadow); 
 //  The brush  
 Paint paint = new Paint(); 
 paint.setColor(Color.RED); 
 paint.setDither(true); 
 paint.setStyle(Paint.Style.STROKE); 
 paint.setStrokeJoin(Paint.Join.ROUND); 
 paint.setStrokeCap(Paint.Cap.ROUND); 
 paint.setStrokeWidth(2); 
 Projection projection = mapView.getProjection(); 
 Point p1 = new Point(); 
 Point p2 = new Point(); 
 Point p3 = new Point(); 
 projection.toPixels(gpoint1, p1); 
 projection.toPixels(gpoint2, p2); 
 projection.toPixels(gpoint3, p3); 
 Path path = new Path(); 
 path.moveTo(p1.x, p1.y); 
 path.lineTo(p2.x, p2.y); 
 path.lineTo(p3.x, p3.y); 
 canvas.drawPath(path, paint);//  Draw a path  
 } 
} 
}

main. xml as follows:

<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout xmlns:Android="http://schemas.android.com/apk/res/android" 
 android:orientation="vertical" android:layout_width="fill_parent" 
 android:layout_height="fill_parent"> 
 <com.google.android.maps.MapView 
 android:id="@+id/mapview" android:layout_width="fill_parent" 
 android:layout_height="fill_parent" 
 android:apiKey="0IB7Kn70qp1LT216Hhb-jmHJ8GLTie4p63O77KQ" /> 
</LinearLayout>

Finally, don't forget to add permission:

< uses-permission Android:name="android.permission.INTERNET"/ >

in < applacation > < /applacation > between < uses-library Android:name="com.google.android.maps" / >

Draw a roadmap:

/** 
*  By parsing google map The returned xml In the map Middle drawing route map 
*/ 
public void drawRoute(){
 String url = "http://maps.google.com/maps/api/directions/xml?origin=23.055291,113.391802" + "&destination=23.046604,113.397510&sensor=false&mode=walking"; 
 HttpGet get = new HttpGet(url); 
 String strResult = ""; 
 try { 
  HttpParams httpParameters = new BasicHttpParams(); 
  HttpConnectionParams.setConnectionTimeout(httpParameters, 3000); 
  HttpClient httpClient = new DefaultHttpClient(httpParameters); 
  HttpResponse httpResponse = null; 
  httpResponse = httpClient.execute(get); 
  if (httpResponse.getStatusLine().getStatusCode() == 200){ 
  strResult = EntityUtils.toString(httpResponse.getEntity()); 
  } 
 } catch (Exception e) { 
  return; 
 } 
 if (-1 == strResult.indexOf("<status>OK</status>")){ 
  Toast.makeText(this, " Failed to get navigation route !", Toast.LENGTH_SHORT).show(); 
  this.finish(); 
  return; 
 } 
 int pos = strResult.indexOf("<overview_polyline>"); 
 pos = strResult.indexOf("<points>", pos + 1); 
 int pos2 = strResult.indexOf("</points>", pos); 
 strResult = strResult.substring(pos + 8, pos2); 
 List<GeoPoint> points = decodePoly(strResult); 
 MyOverLay mOverlay = new MyOverLay(points); 
 List<Overlay> overlays = mMapView.getOverlays(); 
 overlays.add(mOverlay); 
 if (points.size() >= 2){ 
  mMapController.animateTo(points.get(0)); 
 } 
 mMapView.invalidate(); 
 } 
/** 
*  Parsing return xml In the overview_polyline Route coding of  
* 
* @param encoded 
* @return 
*/ 
private List<GeoPoint> decodePoly(String encoded) { 
 List<GeoPoint> poly = new ArrayList<GeoPoint>(); 
 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; 
  GeoPoint p = new GeoPoint((int) (((double) lat / 1E5) * 1E6),(int) (((double) lng / 1E5) * 1E6)); 
  poly.add(p); 
 } 
 return poly; 
}

I hope this article has been helpful for your Android programming.