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
OnRequestPermissionResult-free和shouldshowrequestpermissionrationalfree方法:
public static void requestDangerousPermission(AppCompatActivity activity, String permission) {
if (hasPermission(activity, permission)) return;
requestPermission();
new Handler().postDelayed(() -> {
if (activity.getLifecycle().getCurrentState() == Lifecycle.State.RESUMED) {
Intent intent = new Intent(Settings.ACTION_APPLICATION_DETAILS_SETTINGS);
intent.setData(Uri.parse("package:" + context.getPackageName()));
context.startActivity(intent);
}
}, 250);
}
如果没有权限弹出，250ms后打开设备设置(如果选择了“Never ask again”，就是这种情况)。
其他回答
OnRequestPermissionResult-free和shouldshowrequestpermissionrationalfree方法:
public static void requestDangerousPermission(AppCompatActivity activity, String permission) {
if (hasPermission(activity, permission)) return;
requestPermission();
new Handler().postDelayed(() -> {
if (activity.getLifecycle().getCurrentState() == Lifecycle.State.RESUMED) {
Intent intent = new Intent(Settings.ACTION_APPLICATION_DETAILS_SETTINGS);
intent.setData(Uri.parse("package:" + context.getPackageName()));
context.startActivity(intent);
}
}, 250);
}
如果没有权限弹出，250ms后打开设备设置(如果选择了“Never ask again”，就是这种情况)。
我在Android m中写了一个权限请求的简写，这段代码还处理了对旧Android版本的向后兼容性。
所有丑陋的代码都被提取到一个片段中，该片段将自己附加到请求权限的活动上。PermissionRequestManager的使用方法如下:
new PermissionRequestManager()
// We need a AppCompatActivity here, if you are not using support libraries you will have to slightly change
// the PermissionReuqestManager class
.withActivity(this)
// List all permissions you need
.withPermissions(android.Manifest.permission.CALL_PHONE, android.Manifest.permission.READ_CALENDAR)
// This Runnable is called whenever the request was successfull
.withSuccessHandler(new Runnable() {
@Override
public void run() {
// Do something with your permissions!
// This is called after the user has granted all
// permissions, we are one a older platform where
// the user does not need to grant permissions
// manually, or all permissions are already granted
}
})
// Optional, called when the user did not grant all permissions
.withFailureHandler(new Runnable() {
@Override
public void run() {
// This is called if the user has rejected one or all of the requested permissions
L.e(this.getClass().getSimpleName(), "Unable to request permission");
}
})
// After calling this, the user is prompted to grant the rights
.request();
来看看:https://gist.github.com/crysxd/385b57d74045a8bd67c4110c34ab74aa
为了准确地回答这个问题，当用户按下“永不再问”时会发生什么?
重写的方法/函数
onRequestPermissionsResult(requestCode: Int, permissions: Array<out String>, grantResults: IntArray)
grantResult数组显示为空，你可以在这里做些什么?但不是最好的做法。
如何处理“永不再问”?
我正在使用Fragment，它需要READ_EXTERNAL_STORAGE权限。
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
when {
isReadPermissionsGranted() -> {
/**
* Permissions has been Granted
*/
getDirectories()
}
isPermissionDeniedBefore() -> {
/**
* User has denied before, explain why we need the permission and ask again
*/
updateUIForDeniedPermissions()
checkIfPermissionIsGrantedNow()
}
else -> {
/**
* Need to ask For Permissions, First Time
*/
checkIfPermissionIsGrantedNow()
/**
* If user selects, "Dont Ask Again" it will never ask again! so just update the UI for Denied Permissions
*/
updateUIForDeniedPermissions()
}
}
}
其他的函数是微不足道的。
// Is Read Write Permissions Granted
fun isReadWritePermissionGranted(context: Context): Boolean {
return (ContextCompat.checkSelfPermission(
context as Activity,
Manifest.permission.READ_EXTERNAL_STORAGE
) == PackageManager.PERMISSION_GRANTED) and
(ContextCompat.checkSelfPermission(
context,
Manifest.permission.WRITE_EXTERNAL_STORAGE
) == PackageManager.PERMISSION_GRANTED)
}
fun isReadPermissionDenied(context: Context) : Boolean {
return ActivityCompat.shouldShowRequestPermissionRationale(
context as Activity,
PermissionsUtils.READ_EXTERNAL_STORAGE_PERMISSIONS)
}
你可以使用
shouldShowRequestPermissionRationale()
内部
onRequestPermissionsResult()
请看下面的例子:
当用户点击按钮时检查是否有权限:
@Override
public void onClick(View v) {
if (v.getId() == R.id.appCompatBtn_changeProfileCoverPhoto) {
if (Build.VERSION.SDK_INT < 23) { // API < 23 don't need to ask permission
navigateTo(MainActivity.class); // Navigate to activity to change photos
} else {
if (ContextCompat.checkSelfPermission(SettingsActivity.this, Manifest.permission.WRITE_EXTERNAL_STORAGE)
!= PackageManager.PERMISSION_GRANTED) {
// Permission is not granted yet. Ask for permission...
requestWriteExternalPermission();
} else {
// Permission is already granted, good to go :)
navigateTo(MainActivity.class);
}
}
}
}
当用户回答权限对话框时，我们将进入onRequestPermissionResult:
@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
super.onRequestPermissionsResult(requestCode, permissions, grantResults);
if (requestCode == WRITE_EXTERNAL_PERMISSION_REQUEST_CODE) {
// Case 1. Permission is granted.
if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
if (ContextCompat.checkSelfPermission(SettingsActivity.this, Manifest.permission.WRITE_EXTERNAL_STORAGE)
== PackageManager.PERMISSION_GRANTED) {
// Before navigating, I still check one more time the permission for good practice.
navigateTo(MainActivity.class);
}
} else { // Case 2. Permission was refused
if (ActivityCompat.shouldShowRequestPermissionRationale(this, Manifest.permission.WRITE_EXTERNAL_STORAGE)) {
// Case 2.1. shouldShowRequest... returns true because the
// permission was denied before. If it is the first time the app is running we will
// end up in this part of the code. Because he need to deny at least once to get
// to onRequestPermissionsResult.
Snackbar snackbar = Snackbar.make(findViewById(R.id.relLayout_container), R.string.you_must_verify_permissions_to_send_media, Snackbar.LENGTH_LONG);
snackbar.setAction("VERIFY", new View.OnClickListener() {
@Override
public void onClick(View v) {
ActivityCompat.requestPermissions(SettingsActivity.this
, new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE}
, WRITE_EXTERNAL_PERMISSION_REQUEST_CODE);
}
});
snackbar.show();
} else {
// Case 2.2. Permission was already denied and the user checked "Never ask again".
// Navigate user to settings if he choose to allow this time.
AlertDialog.Builder builder = new AlertDialog.Builder(this);
builder.setMessage(R.string.instructions_to_turn_on_storage_permission)
.setPositiveButton(getString(R.string.settings), new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
Intent settingsIntent = new Intent(Settings.ACTION_APPLICATION_DETAILS_SETTINGS);
Uri uri = Uri.fromParts("package", getPackageName(), null);
settingsIntent.setData(uri);
startActivityForResult(settingsIntent, 7);
}
})
.setNegativeButton(getString(R.string.not_now), null);
Dialog dialog = builder.create();
dialog.show();
}
}
}
}
相反，你会收到回调onRequestPermissionsResult()作为PERMISSION_DENIED当你再次请求权限时，而落在shouldShowRequestPermissionRationale()的错误条件下
来自Android文档:
When the system asks the user to grant a permission, the user has the option of telling the system not to ask for that permission again. In that case, any time an app uses requestPermissions() to ask for that permission again, the system immediately denies the request. The system calls your onRequestPermissionsResult() callback method and passes PERMISSION_DENIED, the same way it would if the user had explicitly rejected your request again. This means that when you call requestPermissions(), you cannot assume that any direct interaction with the user has taken place.
