Android 如何计算两个位置之间的距离？

我想计算两个位置之间的距离，一个是固定的，第二个是用户的位置。 这是我要计算距离的活动

public class CalDist extends AsyncTask<String, Void, String> {


    protected void onPreExecute(){

    }

    protected String doInBackground(String... arg0) {

                StringBuilder stringBuilder = new StringBuilder();
                Double dist = 0.0;
                try {

                    //destinationAddress = destinationAddress.replaceAll(" ","%20");
                    //String url = "https://maps.googleapis.com/maps/api/distancematrix/json?units=imperial&origins="+fromLatitude+","+fromLongitude+"&destination=" + toLatitude + "," + toLongitude + "&mode=driving&sensor=false&key=AIzaSyBpFhiStQvyV5dbVXmarXhzhvGgGFOfubM";
                    //String url = "https://maps.googleapis.com/maps/api/directions/json?origin=" + fromLatitude + "," + fromLongitude + "&destination=" + toLatitude + "," + toLongitude + "&mode=driving&sensor=false&key=AIzaSyBpFhiStQvyV5dbVXmarXhzhvGgGFOfubM";
                    String url = "https://maps.googleapis.com/maps/api/distancematrix/json?origins="+ fromLatitude + "," + fromLongitude + "&destinations=" + toLatitude + "," + toLongitude + "&mode=driving&sensor=false&key=HereIsMyAPIKey";
                    HttpPost httppost = new HttpPost(url);

                    HttpClient client = new DefaultHttpClient();
                    HttpResponse response;
                    stringBuilder = new StringBuilder();


                    response = client.execute(httppost);
                    HttpEntity entity = response.getEntity();
                    InputStream stream = entity.getContent();
                    int b;
                    while ((b = stream.read()) != -1) {
                        stringBuilder.append((char) b);
                    }
                } catch (ClientProtocolException e) {
                } catch (IOException e) {
                }

                JSONObject jsonObject = new JSONObject();
                try {

                    jsonObject = new JSONObject(stringBuilder.toString());

                    JSONArray array = jsonObject.getJSONArray("routes");

                    JSONObject routes = array.getJSONObject(0);

                    JSONArray legs = routes.getJSONArray("legs");

                    JSONObject steps = legs.getJSONObject(0);

                    JSONObject distance = steps.getJSONObject("distance");

                    Log.i("Distance", distance.toString());
                    dist = Double.parseDouble(distance.getString("text").replaceAll("[^\\.0123456789]","") );
                    //Toast.makeText(this, "", Toast.LENGTH_SHORT).show();

                } catch (JSONException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }

                return Double.toString(dist);
            }

    @Override
    protected void onPostExecute(String result) {
        Toast.makeText(Payment.this, "ResultCalcDist:" +result, Toast.LENGTH_SHORT).show();

    }

用于距离计算的两点

gps = new GPSTracker(Payment.this);
    fromLatitude = gps.getLatitude();
    fromLongitude = gps.getLongitude();
    toLatitude = 23.1914909;
    toLongitude = 72.630121;

这是我的GPS跟踪器，我从那里得到纬度和经度

public class GPSTracker extends Service implements LocationListener {

private final Context mContext;

// flag for GPS status
boolean isGPSEnabled = false;

// flag for network status
final private int REQUEST_LOCAION = 12;
boolean isNetworkEnabled = false;

// flag for GPS status
boolean canGetLocation = false;

Location location; // location
double latitude; // latitude
double longitude; // longitude


// The minimum distance to change Updates in meters
private static final long MIN_DISTANCE_CHANGE_FOR_UPDATES = 10; // 10 meters

// The minimum time between updates in milliseconds
private static final long MIN_TIME_BW_UPDATES = 1000 * 60 * 1; // 1 minute

// Declaring a Location Manager
protected LocationManager locationManager;


public GPSTracker(Context context) {

    this.mContext = context;
    getLocation();
}


public Location getLocation() {

    try {
        locationManager = (LocationManager) mContext.getSystemService(LOCATION_SERVICE);

        // getting GPS status
        isGPSEnabled = locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER);

        // getting network status
        isNetworkEnabled = locationManager
                .isProviderEnabled(LocationManager.NETWORK_PROVIDER);

        if (!isGPSEnabled && !isNetworkEnabled) {
            // no network provider is enabled
        } else {
            this.canGetLocation = true;
            // First get location from Network Provider
            if (isNetworkEnabled) {


                if (ActivityCompat.checkSelfPermission(this, android.Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, android.Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
                    // TODO: Consider calling
                    //    ActivityCompat#requestPermissions
                    // here to request the missing permissions, and then overriding
                    //   public void onRequestPermissionsResult(int requestCode, String[] permissions,
                    //                                          int[] grantResults)
                    // to handle the case where the user grants the permission. See the documentation
                    // for ActivityCompat#requestPermissions for more details.
                    android.support.v13.app.ActivityCompat.requestPermissions((Activity)getApplicationContext(),
                            new String[]{Manifest.permission.ACCESS_FINE_LOCATION},
                            REQUEST_LOCAION);

                }
                locationManager.requestLocationUpdates(
                        LocationManager.NETWORK_PROVIDER,
                        MIN_TIME_BW_UPDATES,
                        MIN_DISTANCE_CHANGE_FOR_UPDATES, this);

                Log.d("Network", "Network");
                if (locationManager != null) {
                    location = locationManager
                            .getLastKnownLocation(LocationManager.NETWORK_PROVIDER);

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

            // if GPS Enabled get lat/long using GPS Services
            if (isGPSEnabled) {
                if (location == null) {

                    locationManager.requestLocationUpdates(
                            LocationManager.GPS_PROVIDER,
                            MIN_TIME_BW_UPDATES,
                            MIN_DISTANCE_CHANGE_FOR_UPDATES, this);

                    Log.d("GPS Enabled", "GPS Enabled");
                    if (locationManager != null) {
                        location = locationManager
                                .getLastKnownLocation(LocationManager.GPS_PROVIDER);

                        if (location != null) {
                            latitude = location.getLatitude();
                            longitude = location.getLongitude();
                        }
                    }
                }
            }
            else
            {
                showSettingsAlert();
            }
        }

    } catch (Exception e) {
        e.printStackTrace();
    }

    return location;
}

/**
 * Stop using GPS listener
 * Calling this function will stop using GPS in your app
 * */

public void stopUsingGPS(){
    if(locationManager != null){
        locationManager.removeUpdates(GPSTracker.this);
    }
}

/**
 * Function to get latitude
 * */

public double getLatitude(){
    if(location != null){
        latitude = location.getLatitude();
    }

    // return latitude
    return latitude;
}

/**
 * Function to get longitude
 * */

public double getLongitude(){
    if(location != null){
        longitude = location.getLongitude();
    }

    // return longitude
    return longitude;
}

/**
 * Function to check GPS/wifi enabled
 * @return boolean
 * */

public boolean canGetLocation() {
    return this.canGetLocation;
}

/**
 * Function to show settings alert dialog
 * On pressing Settings button will lauch Settings Options
 * */

public void showSettingsAlert(){
    AlertDialog.Builder alertDialog = new AlertDialog.Builder(mContext);

    // Setting Dialog Title
    alertDialog.setTitle("GPS is settings");

    // Setting Dialog Message
    alertDialog.setMessage("GPS is not enabled. Do you want to go to settings menu?");

    // On pressing Settings button
    alertDialog.setPositiveButton("Settings", new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface dialog,int which) {
            Intent intent = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS);
            mContext.startActivity(intent);

        }
    });

    // on pressing cancel button
    alertDialog.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface dialog, int which) {
            dialog.cancel();
        }
    });

    // Showing Alert Message
    alertDialog.show();
}

@Override
public void onLocationChanged(Location location) {
}

@Override
public void onProviderDisabled(String provider) {
}

@Override
public void onProviderEnabled(String provider) {
}

@Override
public void onStatusChanged(String provider, int status, Bundle extras) {
}

@Override
public IBinder onBind(Intent arg0) {
    return null;
}

public void onRequestPermissionsResult(int requestCode,
                                       @NonNull String permissions[],
                                       @NonNull int[] grantResults) {
    switch (requestCode) {
        case REQUEST_LOCAION: {
            if ((grantResults.length > 0) && (grantResults[0] +
                    grantResults[1]) == PackageManager.PERMISSION_GRANTED) {
                //Call whatever you want
                Toast.makeText(this, "Permission Granted", Toast.LENGTH_SHORT).show();
            } else {
                Toast.makeText(this, "Permission Denied", Toast.LENGTH_SHORT).show();
            }
            return;
        }
    }
}
}

---

请帮我解决这个问题。

如果你想知道地图上两点之间的距离，你可以使用下面的功能

Location locationA = new Location("point A");

locationA.setLatitude(latA);
locationA.setLongitude(lngA);

Location locationB = new Location("point B");

locationB.setLatitude(latB);
locationB.setLongitude(lngB);

float distance = locationA.distanceTo(locationB);

或者，如果您想通过公路保持距离，则可以使用以下谷歌api：

http://maps.googleapis.com/maps/api/distancematrix/json?origins=54.406505,18.67708&destinations=54.446251,18.570993&mode=driving&language=en-EN&sensor=false

---

若你们想知道地图上两点之间的距离，那个么你们可以使用下面的函数

Location locationA = new Location("point A");

locationA.setLatitude(latA);
locationA.setLongitude(lngA);

Location locationB = new Location("point B");

locationB.setLatitude(latB);
locationB.setLongitude(lngB);

float distance = locationA.distanceTo(locationB);

或者，如果您想通过公路保持距离，则可以使用以下谷歌api：

http://maps.googleapis.com/maps/api/distancematrix/json?origins=54.406505,18.67708&destinations=54.446251,18.570993&mode=driving&language=en-EN&sensor=false

---

这里是以公里（km）为单位的距离

另一个选择是：

Location loc1 = new Location("");
loc1.setLatitude(lat1);
loc1.setLongitude(lon1);

Location loc2 = new Location("");
loc2.setLatitude(lat2);
loc2.setLongitude(lon2);

float distanceInMeters = loc1.distanceTo(loc2);

---

这里是以公里（km）为单位的距离

另一个选择是：

Location loc1 = new Location("");
loc1.setLatitude(lat1);
loc1.setLongitude(lon1);

Location loc2 = new Location("");
loc2.setLatitude(lat2);
loc2.setLongitude(lon2);

float distanceInMeters = loc1.distanceTo(loc2);

---

我想沿着道路计算距离。我想沿着道路计算距离。我想沿着道路计算距离。我想沿着道路计算距离。这是查找道路距离的api

http://maps.googleapis.com/maps/api/distancematrix/json?origins=54.406505，18.67708&目的地=54.446251,18.570993&模式=驾驶&语言=英语&传感器=错误

。。因此，您可以调用此api来查找道路距离。我想计算道路上的距离。以下是查找道路距离的api

http://maps.googleapis.com/maps/api/distancematrix/json?origins=54.406505，18.67708&目的地=54.446251,18.570993&模式=驾驶&语言=英语&传感器=错误

。。因此，您可以调用此api来查找公路距离。