Question

我按照本教程http://developer.android.com/training/location/retrieve-current.html检索了设备的位置，但它无法正常工作。

当我这样做时：

mLastLocation = LocationServices.FusedLocationApi.getLastLocation(mGoogleApiClient);

＆＃34; mLastLocation＆＃34;是空的，为什么？

修改

我试图在Niru的回答中这样做：

public Location setLocation()
    {
        Location location;
        final int MIN_TIME_BW_UPDATES = 300;
        final int MIN_DISTANCE_CHANGE_FOR_UPDATES = 50;
        Criteria criteria = new Criteria();
        criteria.setAccuracy(Criteria.ACCURACY_FINE);
        criteria.setAltitudeRequired(false);
        criteria.setBearingRequired(false);
        criteria.setCostAllowed(true);
        criteria.setPowerRequirement(Criteria.POWER_LOW);

        locationManager = (LocationManager) getSystemService(LOCATION_SERVICE);

        String bestProvider = locationManager.getBestProvider(criteria, true);

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M)
        {
            if (checkSelfPermission(Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && checkSelfPermission(Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {}
        }

        location = locationManager.getLastKnownLocation(bestProvider);

        localStorage.putFloat("latitude", (float) location.getLatitude());
        localStorage.putFloat("longitude", (float) location.getLongitude());
        localStorage.commit();

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



        return location;
    }

    @Override
    public void onLocationChanged(Location location)
    {
        localStorage.putFloat("latitude", (float) location.getLatitude());
        localStorage.putFloat("longitude", (float) location.getLongitude());
        localStorage.commit();
    }

但＆＃34; location＆＃34;是空的，为什么？

Answer 1

您可以尝试以下代码段：

public class LocationProvider
{
    private static final String     TAG         = "DEBUG";
    private static final String[]   provider    = new String[]
                                                {
            LocationManager.GPS_PROVIDER,
            LocationManager.NETWORK_PROVIDER,
            LocationManager.PASSIVE_PROVIDER
                                                };

    public Location getLocationByProvider(Context context)
    {
        Location location = null;
        // LocationManager locationManager = (LocationManager) context.getApplicationContext().getSystemService(Context.LOCATION_SERVICE);
        LocationManager locationManager = (LocationManager) context.getSystemService(Context.LOCATION_SERVICE);
        try
        {
            for (int i = 0; i < provider.length; i++)
            {
                if (locationManager.isProviderEnabled(provider[i]))
                {
                    // locationManager.requestLocationUpdates(provider[i], 0, 0, locationListenerGps);
                    location = locationManager.getLastKnownLocation(provider[i]);
                    if (location != null)
                    {
                        break;
                    }
                }
            }
        }
        catch (IllegalArgumentException e)
        {
            Log.d(TAG, "Cannot acces Provider " + provider);
        }
        return location;
    }

}

您还可以获得最佳提供商，然后从最佳提供商处获取位置。

mLocationManager = (LocationManager) getApplicationContext().getSystemService(Context.LOCATION_SERVICE);
            Criteria criteria = new Criteria();
            criteria.setAccuracy(Criteria.ACCURACY_FINE);
            criteria.setAltitudeRequired(false);
            criteria.setBearingRequired(false);
            criteria.setCostAllowed(true);
            criteria.setPowerRequirement(Criteria.POWER_LOW);
            bestProvider = mLocationManager.getBestProvider(criteria, true);

希望这会对你有所帮助。： - ）

Answer 2

www.web1.com这将返回最后一个已知位置...重新安装应用程序后，它将没有任何最后已知的位置...因此它将导致NPE ...而是使用下面的代码< / p>

        <form  action="http://www.web1.com/" method="post" name="form1" >
                    <table width="326" cellpadding="3" cellspacing="0">
                        <tr>
                            <td style="padding-left:7px; padding-right:7px; width:1px; border-right:1px solid #1e639e;">
                                <img src="logo1.png" height="32px" border="0"/>
                            </td>
                            <td style="padding-left:7px; width:1px; white-space:nowrap;">
                                <input name="textfield" type="text" class="input_text" placeholder="Username"/>
                                <input name="textfield2" type="password" class="input_text" placeholder="Password"/>
                            </td>
                            <td>
                                <img src="http://www.web1.com/app/autonum.php" align="absmiddle">
                            </td>
                            <td>
                                <input name="Authnum" type="text" size="4" maxlength="4" class="za_text" style=" width: 56px; ">
                            </td>
                            <td width="68"><input name="login" type="submit" class="but_submit" id="login" value="LOGIN"/></td>
                            <!--<td width="65">
                                <a href="register.php" class="iframe">
                                    <div class="but_join" style="width:60px;">JOIN NOW</div>
                                </a>
                            </td>-->
                        </tr>
                    </table>
                </form>

Answer 3

文档本身表示，如果location不可用，getLastLocation可能会返回null。如果为null，则在OnConnected（）方法中调用requestLocationUpdate方法，如下所示：

@Override
public void onConnected(Bundle connectionHint) {
    mCurrentLocation = LocationServices.FusedLocationApi.getLastLocation(mGoogleApiClient);
    if (mCurrentLocation == null) {
        LocationServices.FusedLocationApi.requestLocationUpdates(
            mGoogleApiClient, mLocationRequest, this);
    }
}

在调用requestLocationUpdates之前，创建mLocationRequest对象：

mLocationRequest = new LocationRequest();
mLocationRequest.setInterval(10000);   
mLocationRequest.setFastestInterval(5000);
mLocationRequest.setPriority(LocationRequest.PRIORITY_BALANCED_POWER_ACCURACY);

当该位置可用时，OnLocationChanged将自动触发。获取此回调的速率由创建请求对象时放入setInterval（）的时间间隔定义。

@Override
public void onLocationChanged(Location location) {
    mCurrentLocation = location;        
}

您的位置对象将会更新。

请点击此链接：http://developer.android.com/training/location/receive-location-updates.html

Answer 4

由于这篇文章我解决了类似的问题：Permission issues for location in android Marshmallow applicaton。

事实上，如果您使用compileSdkVersion 23（或更高版本），则必须处理新的Android权限系统，如果您希望您的应用程序在Android 6.0+设备上正确运行...可以在此处找到更多信息： http://developer.android.com/training/permissions/index.html

用于测试应用的一种快速而肮脏的解决方法可能是将build.gradle中的compileSdkVersion和targetSdkVersion更改为22 ...

但是，我认为没有关于此的明确错误消息而只是一个空的......这是愚蠢的......

获取Android中的最后一个位置

4 个答案: