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我正在尝试制作一个简单的程序来执行将显示在列表视图中的距离计算。我使用来自 androidhive 的 GPSTracker，并为我的列表活动调用纬度和经度

public class GPSTracker extends Service implements LocationListener {

private final Context mContext;
boolean isGPSEnabled =false;
boolean isNetworkEnabled = false;
boolean canGetLocation = false;
Location location;
double latitude;
double 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);
        isGPSEnabled = locationManager.isProviderEnabled(LocationManager.NETWORK_PROVIDER);
        if(!isGPSEnabled&& !isNetworkEnabled){
            //no network enable
        }else {
            this.canGetLocation = true;
            if(isNetworkEnabled){
                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(isGPSEnabled){
                if(location == null){
                    locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, MIN_TIME_BW_UPDATES, MIN_DISTANCE_CHANGE_FOR_UPDATES, this);
                    if(location != null){
                        latitude = location.getLatitude();
                        longitude = location.getLongitude();
                    }
                }
            }
        }

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

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

    }
}

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

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

    }
    return longitude;
}

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) {
    // TODO Auto-generated method stub

}

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

}

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

}

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

}

@Override
public IBinder onBind(Intent intent) {
    // TODO Auto-generated method stub
    return null;
}
}

和我的列表活动

public class Mobil extends ListFragment implements LocationListener{
GPSTracker gps;
private static final String url = "http://10.0.2.2/tambalban/car.php";  

JSONArray tambalban = null;
ArrayList<HashMap<String, String>> listMobil = new ArrayList<HashMap<String, String>>();
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);             
    new getJSONData().execute();        
}

public class getJSONData extends
        AsyncTask<String, Integer, ArrayList<HashMap<String, String>>> {

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

        JSONParser jParser = new JSONParser();
        JSONObject json = jParser.getJSONFromURL(url);

        gps = new GPSTracker(getActivity()); // is it right calling from GPSTracker?    
        double lat_user = gps.getLatitude(); // get latitude, right?
        double lng_user = gps.getLongitude();
        System.out.println("lat_user : "+lat_user+""); // print in logcat return 0.00
        System.out.println("lng_user : "+lng_user+"");// print in logcat return 0.00    

        try {
            tambalban = json.getJSONArray(TAG_TAMBALBAN);

            for (int i = 0; i < tambalban.length(); i++) {
                JSONObject mtr = tambalban.getJSONObject(i);

                 String id_tb = mtr.getString(TAG_ID);
                 String name_tb = mtr.getString(TAG_NAMA);
                 String address_tb = mtr.getString(TAG_ALAMAT);
                 String telp_tb = mtr.getString(TAG_TELP);
                 String lat = mtr.getString(TAG_LAT);
                 String lng = mtr.getString(TAG_LNG);

                 double lat_tujuan = Double.parseDouble(lat);
                 double lng_tujuan = Double.parseDouble(lng);
                         double distance = hitungJarak(lat_user, lng_user, lat_tujuan, lng_tujuan);
                 distance = RoundDecimal(distance, 2);
                 String dist = Double.toString(distance)+" km";

                 HashMap<String, String> a = new HashMap<String, String>();

                a.put(TAG_ID, id_tb);
                a.put(TAG_NAMA, name_tb);
                a.put(TAG_ALAMAT, address_tb);
                a.put(TAG_TELP, telp_tb);
                a.put(TAG_LAT, lat);
                a.put(TAG_LNG, lng);
                a.put(TAG_JARAK, dist);

                listMobil.add(a);                       
            }

        } catch (JSONException e) {
            e.printStackTrace();
        }
        return listMobil;

    }

private double RoundDecimal(double distance, int i) {
        BigDecimal bd = new BigDecimal(distance);
        bd = bd.setScale(i, 6);         
        return bd.doubleValue();
    }


private double hitungJarak(double lat_user, double lng_user,
            double lat_tujuan, double lng_tujuan) {
    double dist;
    double radius = 6371;
    double dLat = Math.toRadians(lat_tujuan - lat_user);
    double dLon = Math.toRadians(lng_tujuan- lng_user);
    double a = Math.sin(dLat/2) * Math.sin(dLat /2)
            + Math.cos(Math.toRadians(lat_user)) * Math.cos(Math.toRadians(lat_tujuan)) 
            * 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));

    dist = radius * c;

        return dist;
    }


    @Override
    protected void onPostExecute(
            ArrayList<HashMap<String, String>> listMobil) {
        // TODO Auto-generated method stub
        super.onPostExecute(listMobil);
        ListAdapter adapter = new SimpleAdapter(getActivity(), listMobil,
                R.layout.list_item, new String[] { TAG_NAMA, TAG_ALAMAT, TAG_JARAK },
                new int[] { R.id.namatb, R.id.alamattb,R.id.jarak });
        setListAdapter(adapter);        
    }

}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    return inflater.inflate(R.layout.list_fragment, container, false);
}

@Override
public void onListItemClick(ListView l, View v, int position, long id) {
    // TODO Auto-generated method stub

    super.onListItemClick(l, v, position, id);
    String pilih = getListAdapter().getItem(position).toString();
    Toast.makeText(getActivity(),
            pilih,
            Toast.LENGTH_LONG).show();



    Intent i = new Intent(getActivity(), DetailDaftar.class);
    Bundle bundle = new Bundle();
    bundle.putString("Selected", pilih);


    i.putExtras(bundle);
    startActivity(i); 
}

@Override
public void onLocationChanged(Location location) {
    // TODO Auto-generated method stub

}

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

}

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

}

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

}   
}

我使用 Sytem.out.println 检查，纬度和经度都返回 0.00。我打电话给当前位置错了吗？谢谢你的帮助。

4

5 回答 5

1

您应该在尝试GPSTracker gps之外创建对象，AsyncTask例如：

 @Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);    
gps = new GPSTracker(getActivity()); // is it right calling from GPSTracker?             
new getJSONData().execute();

}

并将 required 添加permission到您的manifest.xml文件中：

<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" /> 
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
于 2014-02-08T05:30:01.837 回答
0

这是我获取 Longitude 和 Latitude 的代码，它对我很有用

public void setLocation() { 
            LocationManager LM;

    LM = (LocationManager) CurrentContext
            .getSystemService(Context.LOCATION_SERVICE);

    Criteria criteria = new Criteria();
            // adjust ur criteria with ur desired features

    provider = LM.getBestProvider(criteria, true);

    try {

        LM.requestLocationUpdates(provider, 1000, 1, this);

        if (LM != null) {
            Loc = LM.getLastKnownLocation(provider);

            if (Loc != null) {
                userLocation = new Location("");

                userLocation.setLatitude(Loc.getLatitude());
                userLocation.setLongitude(Loc.getLongitude());

            }
        }

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

    LM.removeUpdates(this);
}
于 2014-02-08T07:02:25.840 回答
0

如果您使用模拟器进行测试，那么您应该执行以下操作：

1.在你的编辑器中（我假设你使用的是 Eclipse）去

Window -> Open Perspective -> Show View -> Emulator Control.

2 在那里您会看到两个带有标签“纬度”和“经度”的可编辑文本框。

3 适当设置值并单击发送。

现在您的模拟器具有您设置的值。

于 2014-02-08T06:09:50.850 回答
0

您的 GPSTracker 类将返回当前位置的纬度和经度。我已经检查过了，它正在返回纬度/经度值。在第二部分我没有得到，你试图用 json 做什么，但如果你想在另一个活动中获得纬度经度，那么只需实例化GPSTracker类

内部活动

GPSTracker 追踪器；

和内部onCreate方法

跟踪器=新的 GPSTracker（这个）；

还有一件事 ypu 不能打印或记录doInBackground()方法中的任何语句，因为它只会在后台运行。尝试在onPostExecute()方法中祝酒您的输出

于 2014-02-08T05:09:20.940 回答
0

使用此代码

 public class LocationUpdateService extends Service {


        private LocationManager _locationManager;
        private boolean _gpsEnabled,_networkEnabled;
        @Override 
        public IBinder onBind(Intent arg0) {
            // TODO Auto-generated method stub
            return null;
        }



        @Override
        public void onCreate() {
            // TODO Auto-generated method stub
            super.onCreate();
            _locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
            _gpsEnabled = _locationManager
                    .isProviderEnabled(LocationManager.GPS_PROVIDER);
            _networkEnabled = _locationManager
                    .isProviderEnabled(LocationManager.NETWORK_PROVIDER);

        }

        public void onStart(Intent intent, int startId) {

            Log.e("onStart","onStart");

            if( _gpsEnabled ) {
                _locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER,
                        1000, 0, locationListener);
            } else if ( _networkEnabled ){
                _locationManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER,
                        1000, 0, locationListener);
            }

        };




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

        @Override
        public void onProviderEnabled(String provider) {
        }

        @Override
        public void onProviderDisabled(String provider) {
        }

        @Override
        public void onLocationChanged(final Location location) {
            final Location currentLocation = location;

            Log.e("onLocationChanged", " " + currentLocation);
            _locationManager.removeUpdates(locationListener);

            Toast.makeText(LocationUpdateService_2.this, "Location lat "+currentLocation.getLatitude()+ " long "+currentLocation.getLongitude() , Toast.LENGTH_LONG).show();

    }

    };
于 2014-02-11T11:47:22.590 回答