Question

我尝试实现一个android api来获取当前位置。但是我无法检索纬度和经度。它总是设置为零。而在我的GPSTracker.java中得到一个警告说“用户代码可能拒绝的呼叫应该明确检查是否有权限”。我在AndroidManifest.xml中添加了权限

<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
    <uses-permission android:name="android.permission.INTERNET" />

我的GPSTracker.java是 -

public class GPSTracker extends Service implements LocationListener {

    private final Context mContext;

    // flag for GPS status
    boolean isGPSEnabled = false;

    // flag for network status
    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 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();
    }

    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) {
                    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();
                            }
                        }
                    }
                }
            }

        } 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
     * */


    @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;
    }

}

我的MainActivity.java是 -

public class MainActivity extends Activity {

    Button btnShowLocation;

    // GPSTracker class
    com.example.vk9621.gpstrackingactivity.GPSTracker gps;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        btnShowLocation = (Button) findViewById(R.id.btnShowLocation);

        // show location button click event
        btnShowLocation.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View arg0) {
                // create class object
                gps = new com.example.vk9621.gpstrackingactivity.GPSTracker(MainActivity.this);


                // check if GPS enabled
                if(gps.canGetLocation()){

                    double latitude = gps.getLatitude();
                    double longitude = gps.getLongitude();

                    // \n is for new line
                    Toast.makeText(getApplicationContext(), "Your Location is - \nLat: " + latitude + "\nLong: " + longitude, Toast.LENGTH_LONG).show();
                }else{
                    // can't get location
                    // GPS or Network is not enabled
                    // Ask user to enable GPS/network in settings
                    gps.showSettingsAlert();
                }

            }
        });
    }

}

在手机中运行相同的操作时，我的纬度和经度都等于0。我该如何解决这个问题？

Answer 1

如果使用Android版＆gt; = 23

，请添加运行时权限

final private int REQUEST_CODE_ASK_PERMISSIONS = 123;


 <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/>

        private void requestPermission() {
            if (ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED ) {
                ActivityCompat
                        .requestPermissions(MainActivity.this, new String[]{Manifest.permission.ACCESS_FINE_LOCATION}, REQUEST_CODE_ASK_PERMISSIONS);
            }
        }

    @Override
    public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
        switch (requestCode) {
            case REQUEST_CODE_ASK_PERMISSIONS:
                if (grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                    // Permission Granted
                    Toast.makeText(MainActivity.this, "Permission Granted", Toast.LENGTH_SHORT)
                            .show();
                } else {
                    // Permission Denied
                    Toast.makeText(MainActivity.this, "Permission Denied", Toast.LENGTH_SHORT)
                            .show();
                }
                break;
            default:
                super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        }
    }

Answer 2

首先你应该添加权限 <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" /> <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" /> 在您的清单文件中，然后在运行时检查权限。

在checkPermissions()方法

中调用onCreate方法

private void checkPermissions() {
        if (Build.VERSION.SDK_INT >= 23) {
            if (!checkAllPermission())
                requestLocationPermission(); 
        } else showSettingDialog();
    }


public boolean checkAllPermission() { 
        int FirstPermissionResult = ContextCompat.checkSelfPermission(getApplicationContext(), ACCESS_FINE_LOCATION); 
        int SecondPermissionResult = ContextCompat.checkSelfPermission(getApplicationContext(), ACCESS_COARSE_LOCATION);   
        return  
                FirstPermissionResult == PackageManager.PERMISSION_GRANTED && 
                SecondPermissionResult == PackageManager.PERMISSION_GRANTED &&

    }

private void requestLocationPermission() {
        ActivityCompat.requestPermissions(MainActivity.this, new String[]
                {   
                        ACCESS_FINE_LOCATION,  
                        ACCESS_COARSE_LOCATION,  
                }, RequestPermissionCode);
    }

@Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        switch (requestCode) {
            case REQUEST_CHECK_SETTINGS:
                switch (resultCode) {
                    case RESULT_OK:
                        Log.e("Settings", "Result Ok");
                        //updateGPSStatus("GPS is enabled");
                        break;
                    case RESULT_CANCELED:
                        Log.e("Settings", "Result Cancel");
                        showSettingDialog();
                        // updateGPSStatus("GPS is disabled");
                        break;
                    default:
                        break;
                }
        }
    }


private void showSettingDialog() {
        LocationRequest locationRequest = LocationRequest.create();
        locationRequest.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY);
        locationRequest.setInterval(30 * 1000);
        locationRequest.setFastestInterval(5 * 1000); //5 sec location update request
        final LocationSettingsRequest.Builder builder = new LocationSettingsRequest.Builder().addLocationRequest(locationRequest);
        builder.setAlwaysShow(true); // whenever gps off, it'll pop-up to start gps

        final PendingResult<LocationSettingsResult> result = LocationServices.SettingsApi.checkLocationSettings(mGoogleApiClient, builder.build());
        result.setResultCallback(new ResultCallback<LocationSettingsResult>() {
            @Override
            public void onResult(@NonNull LocationSettingsResult result) {
                final Status status = result.getStatus();
                final LocationSettingsStates state = result.getLocationSettingsStates();
                switch (status.getStatusCode()) {
                    case LocationSettingsStatusCodes.SUCCESS:
                        // updateGPSStatus("GPS is Enabled");
                        break;
                    case LocationSettingsStatusCodes.RESOLUTION_REQUIRED:
                        try {
                            status.startResolutionForResult(MainActivity.this, REQUEST_CHECK_SETTINGS);

                        } catch (IntentSender.SendIntentException e) {
                            e.printStackTrace();
                        }
                        break;
                    case LocationSettingsStatusCodes.SETTINGS_CHANGE_UNAVAILABLE:
                        break;
                    default:
                        break;
                }
            }
        });
    }

了解更多信息Check this

用户在获取位置时可能会拒绝来电

2 个答案: