Question

我想显示从当前位置到特定固定位置的路线。我使用的是Google API。以下是我的MainActivity

public class MainActivity extends FragmentActivity {

GoogleMap map;
LatLng latLng;
ArrayList<LatLng> markerPoints;
LatLng point1 = new LatLng(21.134200700000000000, 79.125217400000000000);
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main_activity);

    // Initializing
    markerPoints = new ArrayList<LatLng>();

    // Getting reference to SupportMapFragment of the activity_main
    SupportMapFragment supportMapFragment =
            (SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map);
    map = supportMapFragment.getMap();
    map.setMyLocationEnabled(true);

    LocationManager locationManager = (LocationManager) getSystemService(LOCATION_SERVICE);
    Criteria criteria = new Criteria();
    String bestProvider = locationManager.getBestProvider(criteria, true);
    Location location = locationManager.getLastKnownLocation(bestProvider);
    if (location != null) {
        onLocationChanged(location);
    }
    //locationManager.requestLocationUpdates(bestProvider, 20000, 0, this);

    // Getting Map for the SupportMapFragment
    map = supportMapFragment.getMap();

    if(map!=null){

        // Enable MyLocation Button in the Map
        map.setMyLocationEnabled(true);

     // Already two locations
        if(markerPoints.size()>1){
            markerPoints.clear();
            map.clear();
        }

        // Adding new item to the ArrayList
        markerPoints.add(point1);

        // Creating MarkerOptions
        MarkerOptions options = new MarkerOptions();

        // Setting the position of the marker
        options.position(point1);

        /**
        * For the start location, the color of marker is GREEN and
        * for the end location, the color of marker is RED.
        */
        if(markerPoints.size()==1){
            options.icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_GREEN));
        }else if(markerPoints.size()==2){
            options.icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_RED));
        }

        // Add new marker to the Google Map Android API V2
        map.addMarker(options);

        // Checks, whether start and end locations are captured
        if(markerPoints.size() >= 2){
            LatLng origin = markerPoints.get(0);
            LatLng dest = markerPoints.get(1);


            // Getting URL to the Google Directions API
            String url = getDirectionsUrl(origin, dest);

            DownloadTask downloadTask = new DownloadTask();

            // Start downloading json data from Google Directions API
            downloadTask.execute(url);
        }
    }
    }


private String getDirectionsUrl(LatLng origin,LatLng dest){

    // Origin of route
    String str_origin = "origin="+origin.latitude+","+origin.longitude;

    // Destination of route
    String str_dest = "destination="+dest.latitude+","+dest.longitude;

    // Sensor enabled
    String sensor = "sensor=false";

    // Building the parameters to the web service
    String parameters = str_origin+"&"+str_dest+"&"+sensor;

    // Output format
    String output = "json";

    // Building the url to the web service
    String url = "https://maps.googleapis.com/maps/api/directions/"+output+"?"+parameters;

    return url;
}
/** A method to download json data from url */
private String downloadUrl(String strUrl) throws IOException{
    String data = "";
    InputStream iStream = null;
    HttpURLConnection urlConnection = null;
    try{
        URL url = new URL(strUrl);

        // Creating an http connection to communicate with url
        urlConnection = (HttpURLConnection) url.openConnection();

        // Connecting to url
        urlConnection.connect();

        // Reading data from url
        iStream = urlConnection.getInputStream();

        BufferedReader br = new BufferedReader(new InputStreamReader(iStream));

        StringBuffer sb = new StringBuffer();

        String line = "";
        while( ( line = br.readLine()) != null){
            sb.append(line);
        }

        data = sb.toString();

        br.close();

    }catch(Exception e){
        Log.d("Exception while downloading url", e.toString());
    }finally{
        iStream.close();
        urlConnection.disconnect();
    }
    return data;
}

// Fetches data from url passed
private class DownloadTask extends AsyncTask<String, Void, String>{

    // Downloading data in non-ui thread
    @Override
    protected String doInBackground(String... url) {

        // For storing data from web service
        String data = "";

        try{
            // Fetching the data from web service
            data = downloadUrl(url[0]);
        }catch(Exception e){
            Log.d("Background Task",e.toString());
        }
        return data;
    }

    // Executes in UI thread, after the execution of
    // doInBackground()
    @Override
    protected void onPostExecute(String result) {
        super.onPostExecute(result);

        ParserTask parserTask = new ParserTask();

        // Invokes the thread for parsing the JSON data
        parserTask.execute(result);
    }
}

/** A class to parse the Google Places in JSON format */
private class ParserTask extends AsyncTask<String, Integer, List<List<HashMap<String,String>>> >{

    // Parsing the data in non-ui thread
    @Override
    protected List<List<HashMap<String, String>>> doInBackground(String... jsonData) {

        JSONObject jObject;
        List<List<HashMap<String, String>>> routes = null;

        try{
            jObject = new JSONObject(jsonData[0]);
            DirectionsJSONParser parser = new DirectionsJSONParser();

            // Starts parsing data
            routes = parser.parse(jObject);
        }catch(Exception e){
            e.printStackTrace();
        }
        return routes;
    }

    // Executes in UI thread, after the parsing process
    @Override
    protected void onPostExecute(List<List<HashMap<String, String>>> result) {
        ArrayList<LatLng> points = null;
        PolylineOptions lineOptions = null;
       // MarkerOptions markerOptions = new MarkerOptions();

        // Traversing through all the routes
        for(int i=0;i<result.size();i++){
            points = new ArrayList<LatLng>();
            lineOptions = new PolylineOptions();

            // Fetching i-th route
            List<HashMap<String, String>> path = result.get(i);

            // Fetching all the points in i-th route
            for(int j=0;j<path.size();j++){
                HashMap<String,String> point = path.get(j);

                double lat = Double.parseDouble(point.get(21.134200700000000000));
                double lng = Double.parseDouble(point.get( 79.125217400000000000));
                LatLng position = new LatLng(lat, lng);

                points.add(position);
                points.add(latLng);

            }

            // Adding all the points in the route to LineOptions
            lineOptions.addAll(points);
            lineOptions.width(2);
            lineOptions.color(Color.RED);
        }

        // Drawing polyline in the Google Map for the i-th route
        map.addPolyline(lineOptions);
    }
}

public void onLocationChanged(Location location) {
    double latitude = location.getLatitude();
    double longitude = location.getLongitude();
    latLng = new LatLng(latitude, longitude);
    map.addMarker(new MarkerOptions().position(latLng));
    map.moveCamera(CameraUpdateFactory.newLatLng(latLng));
    map.animateCamera(CameraUpdateFactory.zoomTo(15));

}


public void onProviderDisabled(String provider) {
    // TODO Auto-generated method stub
}


public void onProviderEnabled(String provider) {
    // TODO Auto-generated method stub
}


public void onStatusChanged(String provider, int status, Bundle extras) {
    // TODO Auto-generated method stub
}

private boolean isGooglePlayServicesAvailable() {
    int status = GooglePlayServicesUtil.isGooglePlayServicesAvailable(this);
    if (ConnectionResult.SUCCESS == status) {
        return true;
    } else {
        GooglePlayServicesUtil.getErrorDialog(status, this, 0).show();
        return false;
    }
}

}

在这里，我将获得两个位置的地图，但不是路线。

Answer 1

我不认识你的代码错误，但我认为你想从两点开始绘制路线，这就是我的所作所为：

解析路线

"grunt-pleeease": "zeorin/grunt-pleeease#sourcemap-external",

解码Poly

              try {
                    //Tranform the string into a json object
                    final JSONObject json = new JSONObject(result);
                    JSONArray routeArray = json.getJSONArray("routes");
                    JSONObject routes = routeArray.getJSONObject(0);
                    JSONObject overviewPolylines = routes.getJSONObject("overview_polyline");
                    String encodedString = overviewPolylines.getString("points");
                    list = decodePoly(encodedString);
                } catch (JSONException e) {

                }

画线

private List<LatLng> decodePoly(String encoded) {

    List<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 p = new LatLng((((double) lat / 1E5)),
                (((double) lng / 1E5)));
        poly.add(p);
    }

    return poly;
}

希望帮助：）

如何在android中显示从当前位置到固定目的地的路线

1 个答案: