Sample Google Map Driving Direction.

1. Create a Customized Overlay Components.
2. Create a Map View Layout.
3. Get the Direction Data using the google Service.
4. Parse the Data and Generate geopoints
5. Draw the path using the customized Overlay Components


Create a Customized Overlay Components.
This components are used to draw the rount, which extends the overlay class.
Reference : http://about-android.blogspot.com/2010/03/steps-to-place-marker-in-map-overlay.html

Create a Map View Layout
Create a Map View and add create a mainactivity.
Reference :http://about-android.blogspot.com/2010/02/map-implementation.html

Get the Direction Data using the google Service
Google provides the varity of service to access the google map. In this blog we are using the following service to get the direction data.
http://maps.google.com/maps?f=d&hl=en&saddr=XXXXXXX&daddr=XXXXXXX&ie=UTF8&0&om=0&output=kml
Reference : http://mapki.com/wiki/Google_Map_Parameters

String urlString = "http://maps.google.com/maps?f=d&hl=en&saddr="+srcPlace+"&daddr="+destPlace+"&ie=UTF8&0&om=0&output=kml";       
    HttpURLConnection urlConnection = null;
    URL url = null;
    String pathConent = "";
    try {
        url = new URL(urlString.toString());
        urlConnection = (HttpURLConnection) url.openConnection();
        urlConnection.setRequestMethod("GET");
        urlConnection.setDoOutput(true);
        urlConnection.setDoInput(true);
        urlConnection.connect();
        InoutStream is =  urlConnection.getInputStream();
    } catch (Exception e) {
    }


Parse the Data and Generate geopoints
Here i am using the DOM Parser for parse the Content. You can use SAX parser.

Reference : http://about-android.blogspot.com/2010/02/sample-saxparser-in-android.html

Sample DOM Parser:
    DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
    DocumentBuilder db = dbf.newDocumentBuilder();
    doc = db.parse(urlConnection.getInputStream());
    NodeList nl = doc.getElementsByTagName("LineString");
    for (int s = 0; s < nl.getLength(); s++) {
        Node rootNode = nl.item(s);
        NodeList configItems = rootNode.getChildNodes();
        for (int x = 0; x < configItems.getLength(); x++) {
            Node lineStringNode = configItems.item(x);
            NodeList path = lineStringNode.getChildNodes();
            pathConent = path.item(0).getNodeValue();
        }
    }



The following method is used to access the Url and parse content

private String[] getDirectionData(String srcPlace, String destPlace) {

    String urlString = "http://maps.google.com/maps?f=d&hl=en&saddr="
            + srcPlace + "&daddr=" + destPlace
            + "&ie=UTF8&0&om=0&output=kml";
    Log.d("URL", urlString);
    Document doc = null;
    HttpURLConnection urlConnection = null;
    URL url = null;
    String pathConent = "";
    try {

        url = new URL(urlString.toString());
        urlConnection = (HttpURLConnection) url.openConnection();
        urlConnection.setRequestMethod("GET");
        urlConnection.setDoOutput(true);
        urlConnection.setDoInput(true);
        urlConnection.connect();
        DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
        DocumentBuilder db = dbf.newDocumentBuilder();
        doc = db.parse(urlConnection.getInputStream());

    } catch (Exception e) {
    }

    NodeList nl = doc.getElementsByTagName("LineString");
    for (int s = 0; s < nl.getLength(); s++) {
        Node rootNode = nl.item(s);
        NodeList configItems = rootNode.getChildNodes();
        for (int x = 0; x < configItems.getLength(); x++) {
            Node lineStringNode = configItems.item(x);
            NodeList path = lineStringNode.getChildNodes();
            pathConent = path.item(0).getNodeValue();
        }
    }
    String[] tempContent = pathConent.split(" ");
    return tempContent;
}


Draw the path using the customized Overlay Components
Using the Custom Overlay Component we can draw the line.

    // STARTING POINT
    GeoPoint startGP = new GeoPoint(
            (int) (Double.parseDouble(lngLat[1]) * 1E6), (int) (Double
                    .parseDouble(lngLat[0]) * 1E6));

    myMC = myMapView.getController();
    geoPoint = startGP;
    myMC.setCenter(geoPoint);
    myMC.setZoom(15);
    myMapView.getOverlays().add(new DirectionPathOverlay(startGP, startGP));

    // NAVIGATE THE PATH
    GeoPoint gp1;
    GeoPoint gp2 = startGP;

    for (int i = 1; i < pairs.length; i++) {
        lngLat = pairs[i].split(",");
        gp1 = gp2;
        // watch out! For GeoPoint, first:latitude, second:longitude
        gp2 = new GeoPoint((int) (Double.parseDouble(lngLat[1]) * 1E6),
                (int) (Double.parseDouble(lngLat[0]) * 1E6));
        myMapView.getOverlays().add(new DirectionPathOverlay(gp1, gp2));
        Log.d("xxx", "pair:" + pairs[i]);
    }

    // END POINT
    myMapView.getOverlays().add(new DirectionPathOverlay(gp2, gp2));


Sample Source

Custom Overlay Component : [DirectionPathOverlay.java]

public class DirectionPathOverlay extends Overlay {
    private GeoPoint gp1;
    private GeoPoint gp2;
    public DirectionPathOverlay(GeoPoint gp1, GeoPoint gp2) {
        this.gp1 = gp1;
        this.gp2 = gp2;
    }

    @Override
    public boolean draw(Canvas canvas, MapView mapView, boolean shadow,
            long when) {
        // TODO Auto-generated method stub
        Projection projection = mapView.getProjection();
        if (shadow == false) {
            Paint paint = new Paint();
            paint.setAntiAlias(true);
            Point point = new Point();
            projection.toPixels(gp1, point);
            paint.setColor(Color.BLUE);
            Point point2 = new Point();
            projection.toPixels(gp2, point2);
            paint.setStrokeWidth(2);
            canvas.drawLine((float) point.x, (float) point.y, (float) point2.x,
                    (float) point2.y, paint);
        }
        return super.draw(canvas, mapView, shadow, when);
    }

    @Override
    public void draw(Canvas canvas, MapView mapView, boolean shadow) {
        // TODO Auto-generated method stub

        super.draw(canvas, mapView, shadow);
    }

}



MainAcvity.java

public class MainActivity extends MapActivity {
    MapView myMapView = null;
    MapController myMC = null;
    GeoPoint geoPoint = null;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        myMapView = (MapView) findViewById(R.id.mapid);
        geoPoint = null;
        myMapView.setSatellite(false);

        String pairs[] = getDirectionData("trichy", "thanjavur");
        String[] lngLat = pairs[0].split(",");

        // STARTING POINT
        GeoPoint startGP = new GeoPoint(
                (int) (Double.parseDouble(lngLat[1]) * 1E6), (int) (Double
                        .parseDouble(lngLat[0]) * 1E6));

        myMC = myMapView.getController();
        geoPoint = startGP;
        myMC.setCenter(geoPoint);
        myMC.setZoom(15);
        myMapView.getOverlays().add(new DirectionPathOverlay(startGP, startGP));

        // NAVIGATE THE PATH
        GeoPoint gp1;
        GeoPoint gp2 = startGP;

        for (int i = 1; i < pairs.length; i++) {
            lngLat = pairs[i].split(",");
            gp1 = gp2;
            // watch out! For GeoPoint, first:latitude, second:longitude
            gp2 = new GeoPoint((int) (Double.parseDouble(lngLat[1]) * 1E6),
                    (int) (Double.parseDouble(lngLat[0]) * 1E6));
            myMapView.getOverlays().add(new DirectionPathOverlay(gp1, gp2));
            Log.d("xxx", "pair:" + pairs[i]);
        }

        // END POINT
        myMapView.getOverlays().add(new DirectionPathOverlay(gp2, gp2));

        myMapView.getController().animateTo(startGP);
        myMapView.setBuiltInZoomControls(true);
        myMapView.displayZoomControls(true);

    }

    @Override
    protected boolean isRouteDisplayed() {
        // TODO Auto-generated method stub
        return false;
    }

    private String[] getDirectionData(String srcPlace, String destPlace) {

        String urlString = "http://maps.google.com/maps?f=d&hl=en&saddr="
                + srcPlace + "&daddr=" + destPlace
                + "&ie=UTF8&0&om=0&output=kml";
        Log.d("URL", urlString);
        Document doc = null;
        HttpURLConnection urlConnection = null;
        URL url = null;
        String pathConent = "";
        try {

            url = new URL(urlString.toString());
            urlConnection = (HttpURLConnection) url.openConnection();
            urlConnection.setRequestMethod("GET");
            urlConnection.setDoOutput(true);
            urlConnection.setDoInput(true);
            urlConnection.connect();
            DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
            DocumentBuilder db = dbf.newDocumentBuilder();
            doc = db.parse(urlConnection.getInputStream());

        } catch (Exception e) {
        }

        NodeList nl = doc.getElementsByTagName("LineString");
        for (int s = 0; s < nl.getLength(); s++) {
            Node rootNode = nl.item(s);
            NodeList configItems = rootNode.getChildNodes();
            for (int x = 0; x < configItems.getLength(); x++) {
                Node lineStringNode = configItems.item(x);
                NodeList path = lineStringNode.getChildNodes();
                pathConent = path.item(0).getNodeValue();
            }
        }
        String[] tempContent = pathConent.split(" ");
        return tempContent;
    }

}