获取位置 Android

Question

我有一项服务可以获取我 phone 的位置。当我关闭 GPS 并再次打开它时，我无法再获取位置。

有时 return 将纬度和经度设为空但 GPS 开启...

我选中它时有一个复选框，它开始向我的服务器发送我设备的纬度和经度。

这是代码。有人可以帮我优化我的代码吗？

服务

public class LocalizationService extends Service implements Runnable {

private static final int tempo = (30 * 1000); // 1800
private LocationManager locationManager = null;
private Thread t;

@Override
public IBinder onBind(Intent arg0) {
    // TODO Auto-generated method stub
    return null;
}

@Override
public void onCreate() {

    super.onCreate();
}

@Override
public void onStart(Intent intent, int startId) {

}

@Override
public void onDestroy() {
    super.onDestroy();
}

@Override
public int onStartCommand(Intent intent, int flags, int startId) {

    if (t == null || !t.isAlive()) {
        t = new Thread(this, "ServicoId: " + startId);
        t.start();
    }
    return Service.START_STICKY;
}

@Override
public void run() {
    // TODO Auto-generated method stub
    while (true) {
        try {
            sendLocation();
            Thread.sleep(tempo);
        } catch (InterruptedException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
}

public void sendLocation() {

    LatLng latlong = getLocation();

    PolifreteApplication manager = (PolifreteApplication) getApplicationContext();
    Veiculo veiculo = manager.getTransportador().getVeiculo();
    int user = manager.getTransportador().getCodigo();

    if (latlong == null) {

    } else {
        veiculo.setLatitude(latlong.latitude + "");
        veiculo.setLongitude(latlong.longitude + "");

        VeiculoDAL.SendLocationVeiculo(veiculo, user);
    }
}

public LatLng getLocation() {
    // Get the location manager
    LocationManager locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
    Criteria criteria = new Criteria();
    String bestProvider = locationManager.getBestProvider(criteria, false);
    Location location = locationManager.getLastKnownLocation(bestProvider);
    Double lat, lon;
    try {
        lat = location.getLatitude();
        lon = location.getLongitude();
        return new LatLng(lat, lon);
    } catch (NullPointerException e) {
        e.printStackTrace();
        return null;
    }
}

}

ACTIVITY 方法

    public void onCheckboxClicked(View view) {

    if (WebService.conexaoOk()) {

        CheckBox cblocalizacao = (CheckBox) findViewById(R.id.checkboxlocalizacao);

        boolean checked = ((CheckBox) view).isChecked();

        locationManager = (LocationManager) this
                .getSystemService(Context.LOCATION_SERVICE);

        boolean isGPSEnabled = locationManager
                .isProviderEnabled(LocationManager.GPS_PROVIDER);

        switch (view.getId()) {
        case R.id.checkboxlocalizacao:
            if (checked && !isGPSEnabled) {
                cblocalizacao.setChecked(false);
                showSettingsAlert();
            } else if (checked && isGPSEnabled) {
                Intent i = new Intent(this, LocalizationService.class);
                this.startService(i);
            } else {
                cblocalizacao.setChecked(false);
            }
        }
    }
}

Answer 1

如果您想从 Gps 获取位置，请参阅此 link，http://www.androidhive.info/2012/07/android-Gps-location-manager-tutorial/，从 Gps 获取位置不是即时的，您需要实现位置侦听器并等待 Gps 的回调提供商：

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

或者您可以使用网络提供商

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

只需访问 link，您就会找到获得最准确位置的最佳策略..

Answer 2

Udacity 的

This video 提供了有关在 GoogleApiClient 中使用定位服务的想法。由于您的 LocationListener 尝试仅使用网络而非 GPS 获取位置，因此使用以下代码片段：locationManager.getLastKnownLocation(LocationManager.NETWORK_PROVIDER) 可能您正在获取纬度和经度值，但有延迟。我遇到了同样的问题，然后我开始使用 new/latest 定位服务 API 并使用：谷歌 API 客户端。首先你需要实现

GoogleApiClient.ConnectionCallbacks,
        GoogleApiClient.OnConnectionFailedListener,
        LocationListener

你activity想要获取位置数据。

定义

private GoogleApiClient mGoogleApiClient;

mGoogleApiClient = new GoogleApiClient.Builder(this)
                .addApi(LocationServices.API)
                .addConnectionCallbacks(this)
                .addOnConnectionFailedListener(this)
                .build();

如果你还没有添加

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

在清单文件中添加。

更多文档：https://developers.google.com/android/reference/com/google/android/gms/common/api/GoogleApiClient

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