如何在 Flutter 中请求和判断权限

在应用了几个解决方案后，我发现这个问题非常棘手.所以我想和大家分享，这就是为什么我问了这个问题，我回答了

在大多数操作系统上，权限不仅仅在安装时授予应用程序.相反，开发人员必须在应用程序运行时向用户询问权限.

处理权限的最佳方法是使用permission_handler

我们还可以打开设备的应用程序设置，以便用户可以授予权限. 在Android上，我们可以展示请求权限的理由.

1. 将此代码添加到软件包的pubspec.yaml文件中:

   dependencies:
     permission_handler: ^5.0.1+1
   

2. 现在，在您的DART代码中，您可以使用:

   import 'package:permission_handler/permission_handler.dart';
   

3. 在运行时请求权限时，您仍然需要告诉操作系统您的应用可能会使用哪些权限.这需要向Android和iOS特定文件添加权限配置.

   iOS

   • 为你的信息添加权限.plist文件.Here是一个例子.列出所有可能权限的完整列表.

   IMPORTANT:当你想提交应用程序时，你必须包括所有权限选项.这是因为permission_handler插件涉及所有不同的SDK，而且静态代码分析器(在提交应用程序时由苹果运行)会检测到这一点，如果在Info.plist中找不到匹配的权限选项，就会断言.有关这方面的更多信息，请访问here.

1. 将以下内容添加到您的Podfile文件中:

   post_install do |installer|
     installer.pods_project.targets.each do |target|
       flutter_additional_ios_build_settings(target)
       target.build_configurations.each do |config|
               config.build_settings['GCC_PREPROCESSOR_DEFINITIONS'] ||= [
                  '$(inherited)',
   
                  ## dart: PermissionGroup.calendar
                  'PERMISSION_EVENTS=0',
   
                  ## dart: PermissionGroup.reminders
                  'PERMISSION_REMINDERS=0',
   
                  ## dart: PermissionGroup.contacts
                  # 'PERMISSION_CONTACTS=0',
   
                  ## dart: PermissionGroup.camera
                  # 'PERMISSION_CAMERA=0',
   
                  ## dart: PermissionGroup.microphone
                  # 'PERMISSION_MICROPHONE=0',
   
                  ## dart: PermissionGroup.speech
                  'PERMISSION_SPEECH_RECOGNIZER=0',
   
                  ## dart: PermissionGroup.photos
                  # 'PERMISSION_PHOTOS=0',
   
                  ## dart: [PermissionGroup.location, PermissionGroup.locationAlways, PermissionGroup.locationWhenInUse]
                  'PERMISSION_LOCATION=0',
   
                  ## dart: PermissionGroup.notification
                  # 'PERMISSION_NOTIFICATIONS=0',
   
                  ## dart: PermissionGroup.mediaLibrary
                  'PERMISSION_MEDIA_LIBRARY=0',
   
                  ## dart: PermissionGroup.sensors
                  'PERMISSION_SENSORS=0'
                ]
       end
     end
   end
   

2. 删除要使用的权限前面的#个字符.例如，如果您确实需要访问日历，请确保代码如下所示:

   ## dart: PermissionGroup.calendar
   'PERMISSION_EVENTS=0',
   

Android

1. 将以下内容添加到"gradle.properties"文件中:

   android.useAndroidX=true
   android.enableJetifier=true
   

2. 一定要把你的"android/app/build.gradle"文件中的前compileSdkVersion位设为28:

    android {
      compileSdkVersion 30
      ...
    }
   

3. 确保你更换了所有的安卓系统.与AndroidX对应项的依赖关系(完整列表可在此处找到:https://developer.android.com/jetpack/androidx/migrate)

   向您的AndroidManifest.xml%文件添加权限.有Adebug、Amain和Aprofile三个版本，根据你启动应用的方式而定.一般说来，只需在main后版本中添加权限就足够了.下面是一个AndroidManifest.xml版本的示例，其中包含所有可能的权限的完整列表.

Finally you can use like this个

有Permissions个.你可以得到Permission分的status分，也就是granted分、denied分、restricted分或permanentlyDenied分.

    var status = await Permission.photos.status;

    if (status.isDenied) {
      // We didn't ask for permission yet.
    }

    // You can can also directly ask the permission about its status.
    if (await Permission.location.isRestricted) {
       // The OS restricts access, for example because of parental controls.
    }

Call `request()` on a `Permission` to request it. If it has already been granted before, nothing happens.

request()返回Permission的新状态.

    if (await Permission.contacts.request().isGranted) {
      // Either the permission was already granted before or the user just granted it.
    }

    // You can request multiple permissions at once.
    Map<Permission, PermissionStatus> statuses = await [
      Permission.location,
      Permission.storage,
    ].request();
    print(statuses[Permission.location]);

On Android, you can show a rationale for using permission:

    bool isShown = await Permission.contacts.shouldShowRequestRationale;

Full Example个

Container(
  child: Wrap(
    children: <Widget>[
      ListTile(
          leading: Icon(Icons.camera_enhance),
          title: Text(getTranslated(context, "Camera")),
          onTap: () async {
            var status = await Permission.photos.status;
            if (status.isGranted) {
              final pickedFile =
                  await _picker.getImage(source: ImageSource.camera);
              final File file = File(pickedFile.path);
              imageSelected(file);
            } else if (status.isDenied) {
              final pickedFile =
                  await _picker.getImage(source: ImageSource.camera);
              final File file = File(pickedFile.path);
              imageSelected(file);
            } else {
              showDialog(
                  context: context,
                  builder: (BuildContext context) => CupertinoAlertDialog(
                        title: Text('Camera Permission'),
                        content: Text(
                            'This app needs camera access to take pictures for upload user profile photo'),
                        actions: <Widget>[
                          CupertinoDialogAction(
                            child: Text('Deny'),
                            onPressed: () => Navigator.of(context).pop(),
                          ),
                          CupertinoDialogAction(
                            child: Text('Settings'),
                            onPressed: () => openAppSettings(),
                          ),
                        ],
                      ));
            }
          }),
    ],
  ),
)