0

我在 android 中使用 google maps api v2。我已经放置了一个标记。我怎样才能获得当前位置和标记之间的方向。任何帮助都会很棒。

4

1 回答 1

4

看看我在一篇文章中提供的这段代码，用于从 Google Direction API 创建折线，如果你想从其他来源获取数据，你可以更改获取数据的类，但这就是你的做法。创建一个负责获取方向和解析的类：

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="+ mode;

    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) {
    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();
}

public int getDurationValue (Document doc) {
    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());
}

public String getDistanceText (Document doc) {
    NodeList nl1 = doc.getElementsByTagName("distance");
    Node node1 = nl1.item(0);
    NodeList nl2 = node1.getChildNodes();
    Node node2 = nl2.item(getNodeIndex(nl2, "text"));
    Log.i("DistanceText", node2.getTextContent());
    return node2.getTextContent();
}

public int getDistanceValue (Document doc) {
    NodeList nl1 = doc.getElementsByTagName("distance");
    Node node1 = nl1.item(0);
    NodeList nl2 = node1.getChildNodes();
    Node node2 = nl2.item(getNodeIndex(nl2, "value"));
    Log.i("DistanceValue", node2.getTextContent());
    return Integer.parseInt(node2.getTextContent());
}

public String getStartAddress (Document doc) {
    NodeList nl1 = doc.getElementsByTagName("start_address");
    Node node1 = nl1.item(0);
    Log.i("StartAddress", node1.getTextContent());
    return node1.getTextContent();
}

public String getEndAddress (Document doc) {
    NodeList nl1 = doc.getElementsByTagName("end_address");
    Node node1 = nl1.item(0);
    Log.i("StartAddress", node1.getTextContent());
    return node1.getTextContent();
}

public String getCopyRights (Document doc) {
    NodeList nl1 = doc.getElementsByTagName("copyrights");
    Node node1 = nl1.item(0);
    Log.i("CopyRights", node1.getTextContent());
    return node1.getTextContent();
}

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;
}
}

创建一个 getDirections AsyncTask：

public class GetDirectionsAsyncTask extends AsyncTask<Map<String, String>, Object, ArrayList<LatLng>> {

public static final String USER_CURRENT_LAT = "user_current_lat";
public static final String USER_CURRENT_LONG = "user_current_long";
public static final String DESTINATION_LAT = "destination_lat";
public static final String DESTINATION_LONG = "destination_long";
public static final String DIRECTIONS_MODE = "directions_mode";
private MapFragmentActivity activity;
private String url;

private Exception exception;

private Dialog progressDialog;

public GetDirectionsAsyncTask(MapFragmentActivity activity /*String url*/) 
{
    super();
    this.activity = activity;

    //  this.url = url;
}

public void onPreExecute() {
    progressDialog = DialogUtils.createProgressDialog(activity, activity.getString(R.string.get_data_dialog_message));
    progressDialog.show();
}

@Override
public void onPostExecute(ArrayList<LatLng> result) {
    progressDialog.dismiss();

    if (exception == null) {
        activity.handleGetDirectionsResult(result);
    } else {
        processException();
    }
}

@Override
protected ArrayList<LatLng> doInBackground(Map<String, String>... params) {

    Map<String, String> paramMap = params[0];
    try{
        LatLng fromPosition = new LatLng(Double.valueOf(paramMap.get(USER_CURRENT_LAT)) , Double.valueOf(paramMap.get(USER_CURRENT_LONG)));
        LatLng toPosition = new LatLng(Double.valueOf(paramMap.get(DESTINATION_LAT)) , Double.valueOf(paramMap.get(DESTINATION_LONG)));
        GMapV2Direction md = new GMapV2Direction();
        Document doc = md.getDocument(fromPosition, toPosition, paramMap.get(DIRECTIONS_MODE));
        ArrayList<LatLng> directionPoints = md.getDirection(doc);
        return directionPoints;

    }
    catch (Exception e) {
        exception = e;
        return null;
    }
}

private void processException() {
    Toast.makeText(activity, activity.getString(R.string.error_when_retrieving_data), 3000).show();
}

}

在您Activity创建这两种方法时：

public void handleGetDirectionsResult(ArrayList<LatLng> directionPoints)
{
    Polyline newPolyline;
    GoogleMap mMap = ((SupportMapFragment)getSupportFragmentManager().findFragmentById(R.id.map)).getMap(); 
    PolylineOptions rectLine = new PolylineOptions().width(3).color(Color.RED);

    for(int i = 0 ; i < directionPoints.size() ; i++) 
    {          
        rectLine.add(directionPoints.get(i));
    }
    newPolyline = mMap.addPolyline(rectLine);
}


public void findDirections(double fromPositionDoubleLat, double fromPositionDoubleLong, double toPositionDoubleLat, double toPositionDoubleLong, String mode)
{
    Map<String, String> map = new HashMap<String, String>();
    map.put(GetDirectionsAsyncTask.USER_CURRENT_LAT, String.valueOf(fromPositionDoubleLat));
    map.put(GetDirectionsAsyncTask.USER_CURRENT_LONG, String.valueOf(fromPositionDoubleLong));
    map.put(GetDirectionsAsyncTask.DESTINATION_LAT, String.valueOf(toPositionDoubleLat));
    map.put(GetDirectionsAsyncTask.DESTINATION_LONG, String.valueOf(toPositionDoubleLong));
    map.put(GetDirectionsAsyncTask.DIRECTIONS_MODE, mode);

    GetDirectionsAsyncTask asyncTask = new GetDirectionsAsyncTask(this);
    asyncTask.execute(map); 
}

最后运行这个方法来创建Polyline：

findDirections(AppObj.getInstance().currentUserLocation.getLatitude(),
                                                   AppObj.getInstance().currentUserLocation.getLongitude(),
                                                   clickMarkerLatLng.latitude, clickMarkerLatLng.longitude, GMapV2Direction.MODE_DRIVING );
于 2013-05-09T11:41:31.973 回答