根据这个:http://developer.android.com/preview/features/runtime-permissions.html#coding一个应用程序可以检查运行时权限和请求权限，如果它还没有被授予。弹出如下对话框:
如果用户拒绝一个重要的权限，在我看来，应用程序应该显示一个解释为什么需要权限和什么影响拒绝。该对话框有两个选项:
重试(再次请求许可) 拒绝(应用程序将工作没有该许可)。
但是，如果用户选中“Never ask again”，则不应该显示带有解释的第二个对话框，特别是如果用户之前已经拒绝了一次。 现在的问题是:我的应用程序如何知道用户是否选中了Never ask again?IMO onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults)没有给我这个信息。
第二个问题是:谷歌是否计划在权限对话框中包含一个自定义消息，以解释为什么应用程序需要权限?这样就不会出现第二个对话框，这肯定会带来更好的用户体验。
当前回答
扩展上面mVck的答案，下面的逻辑确定是否“Never ask again”已经为给定的权限请求进行了检查:
bool bStorage = grantResults[0] == Permission.Granted;
bool bNeverAskForStorage =
!bStorage && (
_bStorageRationaleBefore == true && _bStorageRationaleAfter == false ||
_bStorageRationaleBefore == false && _bStorageRationaleAfter == false
);
摘自下面(完整的例子见这个答案)
private bool _bStorageRationaleBefore;
private bool _bStorageRationaleAfter;
private const int ANDROID_PERMISSION_REQUEST_CODE__SDCARD = 2;
//private const int ANDROID_PERMISSION_REQUEST_CODE__CAMERA = 1;
private const int ANDROID_PERMISSION_REQUEST_CODE__NONE = 0;
public override void OnRequestPermissionsResult(int requestCode, string[] permissions, [GeneratedEnum] Permission[] grantResults)
{
base.OnRequestPermissionsResult(requestCode, permissions, grantResults);
switch (requestCode)
{
case ANDROID_PERMISSION_REQUEST_CODE__SDCARD:
_bStorageRationaleAfter = ShouldShowRequestPermissionRationale(Android.Manifest.Permission.WriteExternalStorage);
bool bStorage = grantResults[0] == Permission.Granted;
bool bNeverAskForStorage =
!bStorage && (
_bStorageRationaleBefore == true && _bStorageRationaleAfter == false ||
_bStorageRationaleBefore == false && _bStorageRationaleAfter == false
);
break;
}
}
private List<string> GetRequiredPermissions(out int requestCode)
{
// Android v6 requires explicit permission granting from user at runtime for security reasons
requestCode = ANDROID_PERMISSION_REQUEST_CODE__NONE; // 0
List<string> requiredPermissions = new List<string>();
_bStorageRationaleBefore = ShouldShowRequestPermissionRationale(Android.Manifest.Permission.WriteExternalStorage);
Permission writeExternalStoragePerm = ApplicationContext.CheckSelfPermission(Android.Manifest.Permission.WriteExternalStorage);
//if(extStoragePerm == Permission.Denied)
if (writeExternalStoragePerm != Permission.Granted)
{
requestCode |= ANDROID_PERMISSION_REQUEST_CODE__SDCARD;
requiredPermissions.Add(Android.Manifest.Permission.WriteExternalStorage);
}
return requiredPermissions;
}
protected override void OnCreate(Bundle savedInstanceState)
{
base.OnCreate(savedInstanceState);
// Android v6 requires explicit permission granting from user at runtime for security reasons
int requestCode;
List<string> requiredPermissions = GetRequiredPermissions(out requestCode);
if (requiredPermissions != null && requiredPermissions.Count > 0)
{
if (requestCode >= ANDROID_PERMISSION_REQUEST_CODE__SDCARD)
{
_savedInstanceState = savedInstanceState;
RequestPermissions(requiredPermissions.ToArray(), requestCode);
return;
}
}
}
OnCreate2(savedInstanceState);
}
其他回答
我有点晚了，我也遇到过类似的问题。解决此问题如下
假设您需要位置权限
请求权限启动器
private final ActivityResultLauncher<String> requestPermissionLauncher =
registerForActivityResult(
new RequestPermission(),
isGranted -> {
if (isGranted) {
// Permission is granted go ahead
} else {
shouldShowRequestPermissionRationale();
}
});
权限检查
private boolean hasPermissions() {
if (checkSelfPermission(requireActivity(), ACCESS_FINE_LOCATION) == PERMISSION_GRANTED) {
// Permission is granted go ahead
} else {
requestPermissionLauncher.launch(ACCESS_FINE_LOCATION);
}
}
检查是否需要显示权限理性/自定义对话来教育用户
private void shouldShowRequestPermissionRationale() {
if (!shouldShowRequestPermissionRationale(ACCESS_FINE_LOCATION)) {
// need to show permission rational custom dialog.
}
}
扩展上面mVck的答案，下面的逻辑确定是否“Never ask again”已经为给定的权限请求进行了检查:
bool bStorage = grantResults[0] == Permission.Granted;
bool bNeverAskForStorage =
!bStorage && (
_bStorageRationaleBefore == true && _bStorageRationaleAfter == false ||
_bStorageRationaleBefore == false && _bStorageRationaleAfter == false
);
摘自下面(完整的例子见这个答案)
private bool _bStorageRationaleBefore;
private bool _bStorageRationaleAfter;
private const int ANDROID_PERMISSION_REQUEST_CODE__SDCARD = 2;
//private const int ANDROID_PERMISSION_REQUEST_CODE__CAMERA = 1;
private const int ANDROID_PERMISSION_REQUEST_CODE__NONE = 0;
public override void OnRequestPermissionsResult(int requestCode, string[] permissions, [GeneratedEnum] Permission[] grantResults)
{
base.OnRequestPermissionsResult(requestCode, permissions, grantResults);
switch (requestCode)
{
case ANDROID_PERMISSION_REQUEST_CODE__SDCARD:
_bStorageRationaleAfter = ShouldShowRequestPermissionRationale(Android.Manifest.Permission.WriteExternalStorage);
bool bStorage = grantResults[0] == Permission.Granted;
bool bNeverAskForStorage =
!bStorage && (
_bStorageRationaleBefore == true && _bStorageRationaleAfter == false ||
_bStorageRationaleBefore == false && _bStorageRationaleAfter == false
);
break;
}
}
private List<string> GetRequiredPermissions(out int requestCode)
{
// Android v6 requires explicit permission granting from user at runtime for security reasons
requestCode = ANDROID_PERMISSION_REQUEST_CODE__NONE; // 0
List<string> requiredPermissions = new List<string>();
_bStorageRationaleBefore = ShouldShowRequestPermissionRationale(Android.Manifest.Permission.WriteExternalStorage);
Permission writeExternalStoragePerm = ApplicationContext.CheckSelfPermission(Android.Manifest.Permission.WriteExternalStorage);
//if(extStoragePerm == Permission.Denied)
if (writeExternalStoragePerm != Permission.Granted)
{
requestCode |= ANDROID_PERMISSION_REQUEST_CODE__SDCARD;
requiredPermissions.Add(Android.Manifest.Permission.WriteExternalStorage);
}
return requiredPermissions;
}
protected override void OnCreate(Bundle savedInstanceState)
{
base.OnCreate(savedInstanceState);
// Android v6 requires explicit permission granting from user at runtime for security reasons
int requestCode;
List<string> requiredPermissions = GetRequiredPermissions(out requestCode);
if (requiredPermissions != null && requiredPermissions.Count > 0)
{
if (requestCode >= ANDROID_PERMISSION_REQUEST_CODE__SDCARD)
{
_savedInstanceState = savedInstanceState;
RequestPermissions(requiredPermissions.ToArray(), requestCode);
return;
}
}
}
OnCreate2(savedInstanceState);
}
如果你想检测所有的“状态”(第一次被拒绝，刚刚被拒绝，刚刚被“Never Ask Again”拒绝或永久拒绝)，你可以做以下事情:
创建2个布尔值:
private boolean beforeClickPermissionRat;
private boolean afterClickPermissionRat;
在请求允许之前设置第一个:
beforeClickPermissionRat = shouldShowRequestPermissionRationale(Manifest.permission.READ_EXTERNAL_STORAGE);
在你的onRequestPermissionsResult方法中设置第二个:
afterClickPermissionRat = shouldShowRequestPermissionRationale(Manifest.permission.READ_EXTERNAL_STORAGE);
使用下面的“真值表”在onRequestPermissionsResult()中做任何你需要的事情(在检查你仍然没有权限之后):
// before after
// FALSE FALSE = Was denied permanently, still denied permanently --> App Settings
// FALSE TRUE = First time deny, not denied permanently yet --> Nothing
// TRUE FALSE = Just been permanently denied --> Changing my caption to "Go to app settings to edit permissions"
// TRUE TRUE = Wasn't denied permanently, still not denied permanently --> Nothing
你可以在onRequestPermissionsResult()中检查shouldShowRequestPermissionRationale()。
https://youtu.be/C8lUdPVSzDk?t=2m23s
在onRequestPermissionsResult()中检查权限是否被授予。如果不是，检查shouldShowRequestPermissionRationale()。
如果此方法返回true，则说明为什么需要此特定权限。然后根据用户的选择再次请求permissions()。 如果它返回false，则显示一个错误消息，权限未授予，应用程序不能继续前进或特定功能被禁用。
下面是示例代码。
@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
super.onRequestPermissionsResult(requestCode, permissions, grantResults);
switch (requestCode) {
case STORAGE_PERMISSION_REQUEST:
if (grantResults.length > 0
&& grantResults[0] == PackageManager.PERMISSION_GRANTED) {
// permission was granted :)
downloadFile();
} else {
// permission was not granted
if (getActivity() == null) {
return;
}
if (ActivityCompat.shouldShowRequestPermissionRationale(getActivity(), Manifest.permission.WRITE_EXTERNAL_STORAGE)) {
showStoragePermissionRationale();
} else {
Snackbar snackbar = Snackbar.make(getView(), getResources().getString(R.string.message_no_storage_permission_snackbar), Snackbar.LENGTH_LONG);
snackbar.setAction(getResources().getString(R.string.settings), new View.OnClickListener() {
@Override
public void onClick(View v) {
if (getActivity() == null) {
return;
}
Intent intent = new Intent();
intent.setAction(Settings.ACTION_APPLICATION_DETAILS_SETTINGS);
Uri uri = Uri.fromParts("package", getActivity().getPackageName(), null);
intent.setData(uri);
OrderDetailFragment.this.startActivity(intent);
}
});
snackbar.show();
}
}
break;
}
}
显然，谷歌maps对位置许可正是这样做的。
public void onRequestPermissionsResult(int requestCode, @NonNull String permissions[], @NonNull int[] grantResults) {
switch (requestCode) {
case PERMISSIONS_REQUEST_EXTERNAL_STORAGE: {
if (grantResults.length > 0) {
if (ActivityCompat.shouldShowRequestPermissionRationale(this, Manifest.permission.WRITE_EXTERNAL_STORAGE)) {
// Denied
} else {
if (ActivityCompat.checkSelfPermission(this, Manifest.permission.WRITE_EXTERNAL_STORAGE) == PackageManager.PERMISSION_GRANTED) {
// To what you want
} else {
// Bob never checked click
}
}
}
}
}
}
