Android GPS定位，得到径纬度

Question

为什么location一直为NULL呢？由与是空
double lat = loc.getLatitude(); //径纬度也就得不到了
double lng = loc.getLongitude();

    LocationManager locationManager = (LocationManager) this.getSystemService(Context.LOCATION_SERVICE);  
    String provider = LocationManager.GPS_PROVIDER;  
    Location location = locationManager.getLastKnownLocation(provider); //为null!!!

以下是取得卫星数，可以正常工作

public void onGpsStatusChanged(int event) { // GPS状态变化时的回调，如卫星数  
                LocationManager locationManager = (LocationManager) GpsActivity.this.getSystemService(Context.LOCATION_SERVICE);  
                GpsStatus status = locationManager.getGpsStatus(null); //取当前状态  
                String satelliteInfo = updateGpsStatus(event, status);
                myTextView.setText(satelliteInfo);//正常，显示:搜索到卫星个数:16
    }
    };
        private String updateGpsStatus(int event, GpsStatus status) {  
            StringBuilder sb2 = new StringBuilder("");  
            if (status == null) {  
                sb2.append("搜索到卫星个数：" +0);  
            } else if (event == GpsStatus.GPS_EVENT_SATELLITE_STATUS) {  
                int maxSatellites = status.getMaxSatellites();  
                Iterator<GpsSatellite> it = status.getSatellites().iterator();  
                numSatelliteList.clear();  
                int count = 0;  
                while (it.hasNext() && count <= maxSatellites) {  
                    GpsSatellite s = it.next();  
                    numSatelliteList.add(s);  
                    count++;  
                }  
                sb2.append("搜索到卫星个数：" + numSatelliteList.size());  
            }
            return sb2.toString();  
        }

在AVD上，这也许是好的~因为可以直接send latitiude...
谁有真机能定位的demo，室内能测最好，只需输出当前径纬度既可，感激不尽~

Answer 1

getLastKnownLocation()只能返回最近的GPS方位，你需要实现一个LocationListener，使用 LocationManager#requestLocationUpdates()获得新位置

基本实现：

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) {
            // 对最近的位置方位进行操作
            //  或者等待更新
        }
        else {
            mLocationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, this);
        }
    }

    @Override
    public void onLocationChanged(Location location) {
        if (location != null) {
            Log.v("Location Changed", location.getLatitude() + " and " + location.getLongitude());
        }
    }
    // ……
}