java - GPS Android - 仅获取一次定位

Question

有没有办法访问 GPS 一次，而不是让 Looper 不断检查位置更新？

在我的场景中，我感兴趣的只是找到当前坐标，而不是与 GPS 卫星的持续连接。有谁知道如何做到这一点？提前致谢。

Answer 1

不要使用 getLastKnownLocation，因为这可能会返回 null 或旧数据。

此代码仅在按下按钮后才获取位置，而不是每次都获取。人们习惯于让位置监听器在每个实例中都进行监听，这会缩短电池寿命，因此请使用我通过大量研究发布的代码片段：

// get the text view and buttons from the xml layout
Button button = (Button) findViewById(R.id.btnGetLocation);
final TextView latitude = (TextView) findViewById(R.id.textview4);
final TextView longitude = (TextView) findViewById(R.id.textview5);
final LocationListener locationListener = new LocationListener() {
        @Override
        public void onLocationChanged(Location location) {
            mlocation = location;
            Log.d("Location Changes", location.toString());
            latitude.setText(String.valueOf(location.getLatitude()));
            longitude.setText(String.valueOf(location.getLongitude()));
        }

        @Override
        public void onStatusChanged(String provider, int status, Bundle extras) {
            Log.d("Status Changed", String.valueOf(status));
        }

        @Override
        public void onProviderEnabled(String provider) {
            Log.d("Provider Enabled", provider);
        }

        @Override
        public void onProviderDisabled(String provider) {
            Log.d("Provider Disabled", provider);
        }
    };

    // Now first make a criteria with your requirements
    // this is done to save the battery life of the device
    // there are various other other criteria you can search for..
    Criteria criteria = new Criteria();
    criteria.setAccuracy(Criteria.ACCURACY_COARSE);
    criteria.setPowerRequirement(Criteria.POWER_LOW);
    criteria.setAltitudeRequired(false);
    criteria.setBearingRequired(false);
    criteria.setSpeedRequired(false);
    criteria.setCostAllowed(true);
    criteria.setHorizontalAccuracy(Criteria.ACCURACY_HIGH);
    criteria.setVerticalAccuracy(Criteria.ACCURACY_HIGH);

    // Now create a location manager
    final LocationManager locationManager = (LocationManager)getSystemService(Context.LOCATION_SERVICE);

   // This is the Best And IMPORTANT part
    final Looper looper = null;

   // Now whenever the button is clicked fetch the location one time
   button.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            locationManager.requestSingleUpdate(criteria, locationListener, looper);
       }
   });

Answer 2

首先检查最后知道的位置是否是最近的。如果没有，我相信您必须设置 onLocationChanged 侦听器，但是一旦您获得第一个有效位置，您就可以随时停止更新流。

添加

public class Example extends Activity implements LocationListener {
    LocationManager mLocationManager;

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

        mLocationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);

        Location location = mLocationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);
        if(location != null && location.getTime() > Calendar.getInstance().getTimeInMillis() - 2 * 60 * 1000) {
            // Do something with the recent location fix
            //  otherwise wait for the update below
        }
        else {
            mLocationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, this);
        }
    }

    public void onLocationChanged(Location location) {
        if (location != null) {
            Log.v("Location Changed", location.getLatitude() + " and " + location.getLongitude());
            mLocationManager.removeUpdates(this);
        }
    }

    // Required functions    
    public void onProviderDisabled(String arg0) {}
    public void onProviderEnabled(String arg0) {}
    public void onStatusChanged(String arg0, int arg1, Bundle arg2) {}
}