android 在程序中开启GPS功能

android 在程序中开启GPS功能
LocationManager locationManager=(LocationManager) getSystemService(Context.LOCATION_SERVICE);      
        
        boolean isEnabled= locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER); 
        if(!isEnabled){ 
            //这段代码可以实现GPS开关状态的切换 
                Intent GPSIntent = new Intent(); 
                GPSIntent.setClassName("com.android.settings", 
                        "com.android.settings.widget.SettingsAppWidgetProvider"); 
                GPSIntent.addCategory("android.intent.category.ALTERNATIVE"); 
                GPSIntent.setData(Uri.parse("custom:3")); 
                try { 
                    PendingIntent.getBroadcast(MainActivity.this, 0, GPSIntent, 0).send(); 
                } catch (CanceledException e) { 
                    e.printStackTrace(); 
                }     
//              Settings.Secure.setLocationProviderEnabled(getContentResolver(), LocationManager.GPS_PROVIDER, true); 
注释掉的代码,表面上看可以简单的实现开启GPS功能,但是运行后发现后没有权限,即使加了权限依旧提示permission denied