对多个提供商使用 requestLocationUpdates

Question

（这是关于 android 中的 LocationManager 类）。

有没有一种方法可以使用 requestLocationUpdates，但以某种方式允许它每次都为我提供最佳活动提供程序的结果？我可以将 getBestProvider 的结果传递给它，但它总是会从该提供程序返回结果，并且如果用户打开/关闭 GPS，它就不会按我的预期工作。

我的代码位于后台服务中。

Answer 1

是否有一种使用 requestLocationUpdates 的方法，但以某种方式允许它每次都为我提供最佳活动提供程序的结果？

不需要，但我们欢迎您为多个提供商注册单独的 LocationListeners。

我可以将 getBestProvider 的结果传递给它，但它总是会返回来自该提供程序的结果，并且如果用户打开/关闭 GPS，它就不会按我的预期工作。

当您的 LocationListener 提供程序启用和禁用时，您会收到通知。如果您当前的提供程序已禁用，您可以向备用提供程序注册 LocationListener。

Answer 2

这就是我所做的：

public class LocationActivity extends Activity implements LocationListener{

    private TextView latituteField;
    private TextView longitudeField;
    private LocationManager locationManager;
    private String provider;
    private TextView outputField;
    private Location location;
    private ScrollView scrollView;
    private Criteria criteria;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_location);

        latituteField = (TextView) findViewById(R.id.lat_textView);
        longitudeField = (TextView) findViewById(R.id.long_textView);
        outputField = (TextView) findViewById(R.id.output_textView);
        scrollView = (ScrollView) findViewById(R.id.scrollView1);

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

        criteria = new Criteria();
        criteria.setAccuracy(Criteria.ACCURACY_FINE);

        List<String> providers = locationManager.getProviders(criteria, true);
        outputField.append("Providers available..." + "\n");
        for (String provider : providers) {
            outputField.append(provider + "\n");
            scrollView.fullScroll(ScrollView.FOCUS_DOWN);
        }

        provider = locationManager.getBestProvider(criteria, true);
        locationManager.requestLocationUpdates(provider, 400, 1, this);

        if (provider != null) {
            outputField.append("Provider " + provider + " has been selected." + "\n");
            scrollView.fullScroll(ScrollView.FOCUS_DOWN);

            if (location != null) {
                onLocationChanged(location);
            } else {
                latituteField.setText("Location not available");
                longitudeField.setText("Location not available");
            }
          } else {
            outputField.append("No provider selected" + "\n");
            scrollView.fullScroll(ScrollView.FOCUS_DOWN);
          }
    }

    @Override
      protected void onResume() {
        super.onResume();
        locationManager.requestLocationUpdates(provider, 400, 1, this);
      }

    protected void onPause() {
        super.onPause();
        locationManager.removeUpdates(this);
      }

    @Override
    public void onLocationChanged(Location location) {
        double lat =location.getLatitude();
        double lng =location.getLongitude();
        latituteField.setText(String.valueOf(lat));
        longitudeField.setText(String.valueOf(lng));
        outputField.append("New Location: " + String.valueOf(lat) + " " + String.valueOf(lng) + "\n");
        scrollView.fullScroll(ScrollView.FOCUS_DOWN);
    }

    @Override
    public void onProviderDisabled(String dProvider) {
        outputField.append("Provider " + dProvider + " has been disabled." + "\n");
        scrollView.fullScroll(ScrollView.FOCUS_DOWN);

        provider = locationManager.getBestProvider(criteria, true);
        locationManager.requestLocationUpdates(provider, 400, 1, this);

        if (provider != null) {
            outputField.append("Provider " + provider + " has been selected." + "\n");
            scrollView.fullScroll(ScrollView.FOCUS_DOWN);

            if (location != null) {
                onLocationChanged(location);
            } else {
                latituteField.setText("Location not available");
                longitudeField.setText("Location not available");
            }
          } else {
            outputField.append("No provider selected" + "\n");
            scrollView.fullScroll(ScrollView.FOCUS_DOWN);
          }
    }

    @Override
    public void onProviderEnabled(String eProvider) {
        outputField.append("Provider " + eProvider + " has been enabled." + "\n");
        scrollView.fullScroll(ScrollView.FOCUS_DOWN);

        provider = locationManager.getBestProvider(criteria, true);
        locationManager.requestLocationUpdates(provider, 400, 1, this);

        if (provider != null) {
            outputField.append("Provider " + provider + " has been selected." + "\n");
            scrollView.fullScroll(ScrollView.FOCUS_DOWN);

            if (location != null) {
                onLocationChanged(location);
            } else {
                latituteField.setText("Location not available");
                longitudeField.setText("Location not available");
            }
          } else {
            outputField.append("No provider selected" + "\n");
            scrollView.fullScroll(ScrollView.FOCUS_DOWN);
          }
    }

    @Override
    public void onStatusChanged(String provider, int status, Bundle extras) {
        outputField.append("Provider " + provider + " status changed to: " + Integer.toString(status) + "\n");
        scrollView.fullScroll(ScrollView.FOCUS_DOWN);
    }
}

Answer 3

从 API 级别 9 及更高版本开始，可以使用以下方法：

requestLocationUpdates(long minTime, float minDistance, Criteria criteria, PendingIntent intent);

有关使用的更多信息，请参阅文档。