This works great for me:
It’s not my code, I took it from a great answer at stackoverflow but I can’t find this answer now, so here is the code:
Add this class to your project:
package ...;
import java.io.InputStream;
import java.util.ArrayList;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.protocol.BasicHttpContext;
import org.apache.http.protocol.HttpContext;
import org.w3c.dom.Document;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import com.google.android.gms.maps.model.LatLng;
import android.content.Context;
import android.util.Log;
public class GMapV2Direction {
public final static String MODE_DRIVING = "driving";
public final static String MODE_WALKING = "walking";
public GMapV2Direction() {
}
public Document getDocument(LatLng start, LatLng end, String mode) {
String url = "http://maps.googleapis.com/maps/api/directions/xml?"
+ "origin=" + start.latitude + "," + start.longitude
+ "&destination=" + end.latitude + "," + end.longitude
+ "&sensor=false&units=metric&mode=driving";
Log.d("url", url);
try {
HttpClient httpClient = new DefaultHttpClient();
HttpContext localContext = new BasicHttpContext();
HttpPost httpPost = new HttpPost(url);
HttpResponse response = httpClient.execute(httpPost, localContext);
InputStream in = response.getEntity().getContent();
DocumentBuilder builder = DocumentBuilderFactory.newInstance()
.newDocumentBuilder();
Document doc = builder.parse(in);
return doc;
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
public String getDurationText(Document doc) {
try {
NodeList nl1 = doc.getElementsByTagName("duration");
Node node1 = nl1.item(0);
NodeList nl2 = node1.getChildNodes();
Node node2 = nl2.item(getNodeIndex(nl2, "text"));
Log.i("DurationText", node2.getTextContent());
return node2.getTextContent();
} catch (Exception e) {
return "0";
}
}
public int getDurationValue(Document doc) {
try {
NodeList nl1 = doc.getElementsByTagName("duration");
Node node1 = nl1.item(0);
NodeList nl2 = node1.getChildNodes();
Node node2 = nl2.item(getNodeIndex(nl2, "value"));
Log.i("DurationValue", node2.getTextContent());
return Integer.parseInt(node2.getTextContent());
} catch (Exception e) {
return -1;
}
}
public String getDistanceText(Document doc) {
/*
* while (en.hasMoreElements()) { type type = (type) en.nextElement();
*
* }
*/
try {
NodeList nl1;
nl1 = doc.getElementsByTagName("distance");
Node node1 = nl1.item(nl1.getLength() - 1);
NodeList nl2 = null;
nl2 = node1.getChildNodes();
Node node2 = nl2.item(getNodeIndex(nl2, "value"));
Log.d("DistanceText", node2.getTextContent());
return node2.getTextContent();
} catch (Exception e) {
return "-1";
}
/*
* NodeList nl1; if(doc.getElementsByTagName("distance")!=null){ nl1=
* doc.getElementsByTagName("distance");
*
* Node node1 = nl1.item(nl1.getLength() - 1); NodeList nl2 = null; if
* (node1.getChildNodes() != null) { nl2 = node1.getChildNodes(); Node
* node2 = nl2.item(getNodeIndex(nl2, "value")); Log.d("DistanceText",
* node2.getTextContent()); return node2.getTextContent(); } else return
* "-1";} else return "-1";
*/
}
public int getDistanceValue(Document doc) {
try {
NodeList nl1 = doc.getElementsByTagName("distance");
Node node1 = null;
node1 = nl1.item(nl1.getLength() - 1);
NodeList nl2 = node1.getChildNodes();
Node node2 = nl2.item(getNodeIndex(nl2, "value"));
Log.i("DistanceValue", node2.getTextContent());
return Integer.parseInt(node2.getTextContent());
} catch (Exception e) {
return -1;
}
/*
* NodeList nl1 = doc.getElementsByTagName("distance"); Node node1 =
* null; if (nl1.getLength() > 0) node1 = nl1.item(nl1.getLength() - 1);
* if (node1 != null) { NodeList nl2 = node1.getChildNodes(); Node node2
* = nl2.item(getNodeIndex(nl2, "value")); Log.i("DistanceValue",
* node2.getTextContent()); return
* Integer.parseInt(node2.getTextContent()); } else return 0;
*/
}
public String getStartAddress(Document doc) {
try {
NodeList nl1 = doc.getElementsByTagName("start_address");
Node node1 = nl1.item(0);
Log.i("StartAddress", node1.getTextContent());
return node1.getTextContent();
} catch (Exception e) {
return "-1";
}
}
public String getEndAddress(Document doc) {
try {
NodeList nl1 = doc.getElementsByTagName("end_address");
Node node1 = nl1.item(0);
Log.i("StartAddress", node1.getTextContent());
return node1.getTextContent();
} catch (Exception e) {
return "-1";
}
}
public String getCopyRights(Document doc) {
try {
NodeList nl1 = doc.getElementsByTagName("copyrights");
Node node1 = nl1.item(0);
Log.i("CopyRights", node1.getTextContent());
return node1.getTextContent();
} catch (Exception e) {
return "-1";
}
}
public ArrayList<LatLng> getDirection(Document doc) {
NodeList nl1, nl2, nl3;
ArrayList<LatLng> listGeopoints = new ArrayList<LatLng>();
nl1 = doc.getElementsByTagName("step");
if (nl1.getLength() > 0) {
for (int i = 0; i < nl1.getLength(); i++) {
Node node1 = nl1.item(i);
nl2 = node1.getChildNodes();
Node locationNode = nl2
.item(getNodeIndex(nl2, "start_location"));
nl3 = locationNode.getChildNodes();
Node latNode = nl3.item(getNodeIndex(nl3, "lat"));
double lat = Double.parseDouble(latNode.getTextContent());
Node lngNode = nl3.item(getNodeIndex(nl3, "lng"));
double lng = Double.parseDouble(lngNode.getTextContent());
listGeopoints.add(new LatLng(lat, lng));
locationNode = nl2.item(getNodeIndex(nl2, "polyline"));
nl3 = locationNode.getChildNodes();
latNode = nl3.item(getNodeIndex(nl3, "points"));
ArrayList<LatLng> arr = decodePoly(latNode.getTextContent());
for (int j = 0; j < arr.size(); j++) {
listGeopoints.add(new LatLng(arr.get(j).latitude, arr
.get(j).longitude));
}
locationNode = nl2.item(getNodeIndex(nl2, "end_location"));
nl3 = locationNode.getChildNodes();
latNode = nl3.item(getNodeIndex(nl3, "lat"));
lat = Double.parseDouble(latNode.getTextContent());
lngNode = nl3.item(getNodeIndex(nl3, "lng"));
lng = Double.parseDouble(lngNode.getTextContent());
listGeopoints.add(new LatLng(lat, lng));
}
}
return listGeopoints;
}
private int getNodeIndex(NodeList nl, String nodename) {
for (int i = 0; i < nl.getLength(); i++) {
if (nl.item(i).getNodeName().equals(nodename))
return i;
}
return -1;
}
private ArrayList<LatLng> decodePoly(String encoded) {
ArrayList<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 position = new LatLng((double) lat / 1E5, (double) lng / 1E5);
poly.add(position);
}
return poly;
}
}
Then use this class for your needs.
For example to draw directions:
GMapV2Direction md = new GMapV2Direction();
mMap = ((SupportMapFragment) getSupportFragmentManager()
.findFragmentById(R.id.map)).getMap();
Document doc = md.getDocument(sourcePosition, destPosition,
GMapV2Direction.MODE_DRIVING);
ArrayList<LatLng> directionPoint = md.getDirection(doc);
PolylineOptions rectLine = new PolylineOptions().width(3).color(
Color.RED);
for (int i = 0; i < directionPoint.size(); i++) {
rectLine.add(directionPoint.get(i));
}
Polyline polylin = mMap.addPolyline(rectLine);
The sourcePosition, destPosition are from the LatLng type, and you give them the wanted points.
I wrote here parts from my code that I think could help, Any question is welcome.