How to create a custom Google Maps

Question

I'm developing an Android application that allows showing a list of POI (Point Of Interest) on a map.

The basic function is simple, I receive from the server a list of coordinates (Latitude and Longitude) in JSON format, I saved this data in an SQLite DB on the device (because I want to use data when the device when is offline) and then I want to display the POI in a "Google Maps".

Now I would like to create a map with all the available POI, for example like this:

This is simple, and this is not a problem, what that I want to know is:

you can do so that it displays a path that crosses all POI (like you're not in navigation mode) but without the voice?

My goal is to create routes POI formats, show in real time how to get from point A to point X, passing through B, C, D etc, but without the voice guidance.

all this is feasible?

Answer 1

Add this class to your project -

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.