要求用户许可的代码：

Question

我使用此代码获取当前位置，它工作正常。但在商店发布后，它就再也无法使用了。应用程序保持锁定在doInBackground函数中。

private class GpsAsync extends AsyncTask<Void, Integer, Boolean> {
    private ContactLocationListener contactLocationListener;
    private Location location;

    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        contactLocationListener = new ContactLocationListener();
        locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, contactLocationListener);
    }

    @Override
    protected Boolean doInBackground(Void... voids) {
        while (location == null) {}
        return null;
    }

    @Override
    protected void onPostExecute(Boolean aBoolean) {
        super.onPostExecute(aBoolean);
        textViewLatitude.setText(String.valueOf(location.getLatitude()));
        textViewLongitude.setText(String.valueOf(location.getLongitude()));
    }

    public class ContactLocationListener implements LocationListener {
        @Override
        public void onLocationChanged(Location loc) {
            location = loc;
        }
        @Override
        public void onStatusChanged(String s, int i, Bundle bundle) {}
        @Override
        public void onProviderEnabled(String s) {}
        @Override
        public void onProviderDisabled(String s) {}
    }
}

我的清单：

<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.CAMERA" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
<uses-feature android:name="android.hardware.location.gps" />

我的许可检查：

if (ContextCompat.checkSelfPermission(getActivity(), Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED &&
                ActivityCompat.checkSelfPermission(getActivity(), Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
            ActivityCompat.requestPermissions(getActivity(), new String[]{Manifest.permission.ACCESS_FINE_LOCATION}, 50);
} else {
    // start GpsAsync
}

Answer 1

两件事：

每当LocationProvider无法提供位置时，doInBackground中的while循环会导致无限循环。它一般很危险。最好做一些＆＃34;警卫＆＃34;周围 - 至少是简单的柜台：
```
protected Boolean doInBackground(Void... voids) {
     Integer count = 0  
     while (location == null||count<10000) {count++}
     return null;
}
```
关于为什么提供程序在发布后为位置返回null的问题。有几个可能的原因，请检查：
- GPS是否可用并在设备上开启？（我想它可能会在发布后在不同的设备上进行测试，其中GPS已关闭）
- 可能的权限问题。自API 23以来，对于位置和其他＆＃34;危险＆＃34;服务，除了在清单中声明之外，它应该被用户接受一次（第一次调用应用程序时弹出）。如果用户＆＃34;拒绝＆＃34;服务 - GPS提供商将始终返回null。
- 另外，请考虑使用＆＃34; getBestProvider＆＃34;如果GPS不可用，如下所示
```
LocationManager locationManager;
String svcName = Context.LOCATION_SERVICE;
locationManager = 
(LocationManager)getSystemService(svcName);
Criteria criteria = new Criteria();
criteria.setAccuracy(Criteria.ACCURACY_FINE);
criteria.setPowerRequirement(Criteria.POWER_LOW);
criteria.setAltitudeRequired(false);
criteria.setBearingRequired(false);
criteria.setSpeedRequired(false);
criteria.setCostAllowed(true);
String provider = locationManager.getBestProvider(criteria, true);
locationManager.getLastKnownLocation(provider);
l = locationManager.getLastKnownLocation(provider);
```

要求用户许可的代码：

        // first check the permission in manifest:
        if (ActivityCompat.checkSelfPermission(this, android.Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, android.Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {


            //  then ask for GPS permission from user:
            ActivityCompat.requestPermissions(MainActivity.this, new String[]{android.Manifest.permission.ACCESS_COARSE_LOCATION, android.Manifest.permission.ACCESS_FINE_LOCATION}, 1);
        }

     ///////////////////////////////////////////////////////////////////////////////
     ///// NOTE: Even if we declared the permission in manifest, user can decline.
     /// So we anyway will do try/catch on pemission exception later on!
     ///////////////////////////////////////////////////////////////////////////////

Android：在Play商店发布后无法获取当前位置

1 个答案:

要求用户许可的代码：