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

一旦用户标记了“不要再问”,该问题就不能再次显示。 但是可以向用户解释,他之前拒绝了权限,必须在设置中授予权限。并参考他的设置,使用以下代码:

@Override
public void onRequestPermissionsResult(int permsRequestCode, String[] permissions, int[] grantResults) {

    if (grantResults.length > 0
            && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
        // now, you have permission go ahead
        // TODO: something

    } else {

        if (ActivityCompat.shouldShowRequestPermissionRationale(MainActivity.this,
                Manifest.permission.READ_CALL_LOG)) {
            // now, user has denied permission (but not permanently!)

        } else {

            // now, user has denied permission permanently!

            Snackbar snackbar = Snackbar.make(findViewById(android.R.id.content), "You have previously declined this permission.\n" +
                "You must approve this permission in \"Permissions\" in the app settings on your device.", Snackbar.LENGTH_LONG).setAction("Settings", new View.OnClickListener() {
            @Override
            public void onClick(View view) {

                startActivity(new Intent(android.provider.Settings.ACTION_APPLICATION_DETAILS_SETTINGS, Uri.parse("package:" + BuildConfig.APPLICATION_ID)));

            }
        });
        View snackbarView = snackbar.getView();
        TextView textView = (TextView) snackbarView.findViewById(android.support.design.R.id.snackbar_text);
        textView.setMaxLines(5);  //Or as much as you need
        snackbar.show();

        }

    }
    return;
}

其他回答

一旦用户标记了“不要再问”,该问题就不能再次显示。 但是可以向用户解释,他之前拒绝了权限,必须在设置中授予权限。并参考他的设置,使用以下代码:

@Override
public void onRequestPermissionsResult(int permsRequestCode, String[] permissions, int[] grantResults) {

    if (grantResults.length > 0
            && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
        // now, you have permission go ahead
        // TODO: something

    } else {

        if (ActivityCompat.shouldShowRequestPermissionRationale(MainActivity.this,
                Manifest.permission.READ_CALL_LOG)) {
            // now, user has denied permission (but not permanently!)

        } else {

            // now, user has denied permission permanently!

            Snackbar snackbar = Snackbar.make(findViewById(android.R.id.content), "You have previously declined this permission.\n" +
                "You must approve this permission in \"Permissions\" in the app settings on your device.", Snackbar.LENGTH_LONG).setAction("Settings", new View.OnClickListener() {
            @Override
            public void onClick(View view) {

                startActivity(new Intent(android.provider.Settings.ACTION_APPLICATION_DETAILS_SETTINGS, Uri.parse("package:" + BuildConfig.APPLICATION_ID)));

            }
        });
        View snackbarView = snackbar.getView();
        TextView textView = (TextView) snackbarView.findViewById(android.support.design.R.id.snackbar_text);
        textView.setMaxLines(5);  //Or as much as you need
        snackbar.show();

        }

    }
    return;
}

这里有一个很好的和简单的方法来检查当前的权限状态:

    @Retention(RetentionPolicy.SOURCE)
    @IntDef({GRANTED, DENIED, BLOCKED_OR_NEVER_ASKED })
    public @interface PermissionStatus {}

    public static final int GRANTED = 0;
    public static final int DENIED = 1;
    public static final int BLOCKED_OR_NEVER_ASKED = 2;

    @PermissionStatus 
    public static int getPermissionStatus(Activity activity, String androidPermissionName) {
        if(ContextCompat.checkSelfPermission(activity, androidPermissionName) != PackageManager.PERMISSION_GRANTED) {
            if(!ActivityCompat.shouldShowRequestPermissionRationale(activity, androidPermissionName)){
                return BLOCKED_OR_NEVER_ASKED;
            }
            return DENIED;
        }
        return GRANTED;
    }

警告:在用户通过用户提示接受/拒绝权限之前,在第一个应用程序启动时返回BLOCKED_OR_NEVER_ASKED(在sdk 23+设备上)

更新:

Android支持库现在似乎也有一个非常类似的类Android .support.v4.content。PermissionChecker,包含checkSelfPermission(),返回:

public static final int PERMISSION_GRANTED = 0;
public static final int PERMISSION_DENIED = -1;
public static final int PERMISSION_DENIED_APP_OP = -2;

在阅读了一些答案后,我发现了许多冗长而令人困惑的答案 我的结论是

if (!ActivityCompat.shouldShowRequestPermissionRationale(this,Manifest.permission.READ_EXTERNAL_STORAGE))
                Toast.makeText(this, "permanently denied", Toast.LENGTH_SHORT).show();

您可以通过检查权限原理是否显示在onRequestPermissionsResult()回调方法中来确定它。如果您发现任何权限集永远不会再次请求,您可以请求用户从设置中授予权限。

我的完整实现如下所示。它适用于单个或多个权限请求。使用以下或直接使用我的库。

@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
    if(permissions.length == 0){
        return;
    }
    boolean allPermissionsGranted = true;
    if(grantResults.length>0){
        for(int grantResult: grantResults){
            if(grantResult != PackageManager.PERMISSION_GRANTED){
                allPermissionsGranted = false;
                break;
            }
        }
    }
    if(!allPermissionsGranted){
        boolean somePermissionsForeverDenied = false;
        for(String permission: permissions){
            if(ActivityCompat.shouldShowRequestPermissionRationale(this, permission)){
                //denied
                Log.e("denied", permission);
            }else{
                if(ActivityCompat.checkSelfPermission(this, permission) == PackageManager.PERMISSION_GRANTED){
                    //allowed
                    Log.e("allowed", permission);
                } else{
                    //set to never ask again
                    Log.e("set to never ask again", permission);
                    somePermissionsForeverDenied = true;
                }
            }
        }
        if(somePermissionsForeverDenied){
            final AlertDialog.Builder alertDialogBuilder = new AlertDialog.Builder(this);
            alertDialogBuilder.setTitle("Permissions Required")
                    .setMessage("You have forcefully denied some of the required permissions " +
                            "for this action. Please open settings, go to permissions and allow them.")
                    .setPositiveButton("Settings", new DialogInterface.OnClickListener() {
                        @Override
                        public void onClick(DialogInterface dialog, int which) {
                            Intent intent = new Intent(Settings.ACTION_APPLICATION_DETAILS_SETTINGS,
                                    Uri.fromParts("package", getPackageName(), null));
                            intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
                            startActivity(intent);
                        }
                    })
                    .setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
                        @Override
                        public void onClick(DialogInterface dialog, int which) {
                        }
                    })
                    .setCancelable(false)
                    .create()
                    .show();
        }
    } else {
        switch (requestCode) {
            //act according to the request code used while requesting the permission(s).
        }
    }
}

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。