使用permission_handler包：
试试这个：

void _checkPermission(BuildContext context) async {
    FocusScope.of(context).requestFocus(FocusNode());
    Map<Permission, PermissionStatus> statues = await [
      Permission.camera,
      Permission.storage,
      Permission.photos
    ].request();
    PermissionStatus? statusCamera = statues[Permission.camera];
    PermissionStatus? statusStorage = statues[Permission.storage];
    PermissionStatus? statusPhotos = statues[Permission.photos];
    bool isGranted = statusCamera == PermissionStatus.granted &&
        statusStorage == PermissionStatus.granted &&
        statusPhotos == PermissionStatus.granted;
    if (isGranted) {
      //openCameraGallery();
      //_openDialog(context);
    }
    bool isPermanentlyDenied =
        statusCamera == PermissionStatus.permanentlyDenied ||
            statusStorage == PermissionStatus.permanentlyDenied ||
            statusPhotos == PermissionStatus.permanentlyDenied;
    if (isPermanentlyDenied) {
      _showSettingsDialog(context);
    }
  }

import 'package:permission_handler/permission_handler.dart';

Future<bool> checkAndRequestCameraPermissions() async {
  PermissionStatus permission =
      await PermissionHandler().checkPermissionStatus(PermissionGroup.camera);
  if (permission != PermissionStatus.granted) {
    Map<PermissionGroup, PermissionStatus> permissions =
        await PermissionHandler().requestPermissions([PermissionGroup.camera]);
    return permissions[PermissionGroup.camera] == PermissionStatus.granted;
  } else {
    return true;
  }
}
Then every call to the image picker has to be wrapped like this to prevent your app from crashing

if (await checkAndRequestCameraPermissions()) {
  File image = await ImagePicker.pickImage(source: ImageSource.camera);
  // continue with the image ...
}

如果您向“AndroidManifest.xml”文件添加权限，则当您尝试使用图像拾取器时将自动询问权限。我使用相机和拾取器库，因此我将这些权限放在“AndroidManifest.xml”中。

<uses-permission android:name="android.permission.CAMERA"/>
<uses-permission android:name="android.permission.GALLERY"/>

你不需要请求画廊的权限，只需要请求相机的权限，你会自动获得画廊的权限，你可以使用它。