android - 如何在android编程中获得两个地理点之间的精确路线

Question

我正在尝试为自己创建一个谷歌地图示例。目标是计算两个地理点之间的路线。我在尝试找出两点之间的路线时遇到了一些问题。对于我的 map 生成的一个，但我在尝试计算距离和在 map 上生成路线时遇到了一些错误。请原谅我的编码我是 Android 编程的新手。

   import android.content.Context;
   import android.location.Criteria;
   import android.location.Geocoder;
   import android.location.Location;
   import android.location.LocationManager;
   import android.support.v4.app.FragmentActivity;
   import android.os.Bundle;
   import android.util.Log;
   import android.widget.Toast;
   import com.google.android.gms.common.api.GoogleApiClient;
   import com.google.android.gms.location.LocationServices;
   import com.google.android.gms.maps.CameraUpdate;
   import com.google.android.gms.maps.CameraUpdateFactory;
   import com.google.android.gms.maps.GoogleMap;
   import com.google.android.gms.maps.SupportMapFragment;
   import com.google.android.gms.maps.model.CameraPosition;
   import com.google.android.gms.maps.model.LatLng;
   import com.google.android.gms.maps.model.MarkerOptions;

    import java.text.DecimalFormat;

     public class MapsActivity extends FragmentActivity {

private GoogleMap mMap; // Might be null if Google Play services APK is not available.

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_maps);
    setUpMapIfNeeded();
}

@Override
protected void onResume() {
    super.onResume();
    setUpMapIfNeeded();
}

/**
 * Sets up the map if it is possible to do so (i.e., the Google Play services APK is correctly
 * installed) and the map has not already been instantiated.. This will ensure that we only ever
 * call {@link #setUpMap()} once when {@link #mMap} is not null.
 * <p/>
 * If it isn't installed {@link SupportMapFragment} (and
 * {@link com.google.android.gms.maps.MapView MapView}) will show a prompt for the user to
 * install/update the Google Play services APK on their device.
 * <p/>
 * A user can return to this FragmentActivity after following the prompt and correctly
 * installing/updating/enabling the Google Play services. Since the FragmentActivity may not
 * have been completely destroyed during this process (it is likely that it would only be
 * stopped or paused), {@link #onCreate(Bundle)} may not be called again so we should call this
 * method in {@link #onResume()} to guarantee that it will be called.
 */
private void setUpMapIfNeeded() {
    // Do a null check to confirm that we have not already instantiated the map.
    if (mMap == null) {
        // Try to obtain the map from the SupportMapFragment.
        mMap = ((SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map))
                .getMap();
        // Check if we were successful in obtaining the map.
        if (mMap != null) {
            setUpMap();
        }
    }
}

/**
 * This is where we can add markers or lines, add listeners or move the camera. In this case, we
 * just add a marker near Africa.
 * <p/>
 * This should only be called once and when we are sure that {@link #mMap} is not null.
 */

private void setUpMap() {

    mMap.addMarker(new MarkerOptions().position(new LatLng(0, 0)).title("Marker").snippet("Snippet"));

    // Enable MyLocation Layer of Google Map
    mMap.setMyLocationEnabled(true);

    // Get LocationManager object from System Service LOCATION_SERVICE
    LocationManager locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);

    // Create a criteria object to retrieve provider
    Criteria criteria = new Criteria();

    // Get the name of the best provider
    String provider = locationManager.getBestProvider(criteria, true);

    // Get Current Location
    Location myLocation = locationManager.getLastKnownLocation(provider);

    // set map type
    mMap.setMapType(GoogleMap.MAP_TYPE_NORMAL);

    // Get latitude of the current location

    Location location = locationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);

    if (location != null) {
        double longitude = location.getLongitude();
        double latitude = location.getLatitude();


        // Get longitude of the current location

        // Create a LatLng object for the current location
        LatLng latLng = new LatLng(latitude, longitude);

        // Show the current location in Google Map
        mMap.moveCamera(CameraUpdateFactory.newLatLng(latLng));

        // Zoom in the Google Map
        //LatLng myCoordinates = new LatLng(latitude, longitude);
        //CameraUpdate yourLocation = CameraUpdateFactory.newLatLngZoom(myCoordinates, 20);
        //mMap.animateCamera(yourLocation);
        mMap.animateCamera(CameraUpdateFactory.zoomTo(20));
        mMap.addMarker(new MarkerOptions().position(new LatLng(latitude, longitude)).title("You are here!").snippet("Consider yourself located"));

    }
    double fromLat = 49.85, fromLon = 24.016667;
    double toLat = 50.45, toLon = 30.523333;
    CalculationByDistance(fromLat,toLat);

}



public double CalculationByDistance(LatLng StartP, LatLng EndP) {
    int Radius = 6371;// radius of earth in Km
    double lat1 = StartP.latitude;
    double lat2 = EndP.latitude;
    double lon1 = StartP.longitude;
    double lon2 = EndP.longitude;
    double dLat = Math.toRadians(lat2 - lat1);
    double dLon = Math.toRadians(lon2 - lon1);
    double a = Math.sin(dLat / 2) * Math.sin(dLat / 2)
            + Math.cos(Math.toRadians(lat1))
            * Math.cos(Math.toRadians(lat2)) * Math.sin(dLon / 2)
            * Math.sin(dLon / 2);
    double c = 2 * Math.asin(Math.sqrt(a));
    double valueResult = Radius * c;
    double km = valueResult / 1;
    DecimalFormat newFormat = new DecimalFormat("####");
    int kmInDec = Integer.valueOf(newFormat.format(km));
    double meter = valueResult % 1000;
    int meterInDec = Integer.valueOf(newFormat.format(meter));
    Log.i("Radius Value", "" + valueResult + "   KM  " + kmInDec
            + " Meter   " + meterInDec);

    return Radius * c;
}


        public void onFinish() {
            // Your code here to do something after the Map is rendered
        }
    }

Answer 1

首先，您需要使用 Google Directions API获取一组您希望在 map 上绘制的点。在调用网络服务并返回结果后，您必须解析类似于 this 的 json。 .

你想要的点在 route->legs->steps->polyline->points 中并且它们被编码所以你需要使用可以找到的代码 here解码它们。

到那时，正如 Neal 指出的那样，您需要获取这些点并将它们添加到 PolylineOptions 并将它们添加到 map 中。