1

我有下一个代码：

public static class AppUser
    {
        static AppUser()
        {
            RestorePreviewUserState();
        }

        private static void RestorePreviewUserState()
        {
            var storedToken = Settings.Authentification.SessionToken; //Here I gets my settings
            var storedUserId = Settings.Authentification.CurrentUserId; 

            if (storedToken == null || storedUserId == default(int)) return;
            AuthToken = storedToken;
            CurrentUserId = storedUserId;
        }

        public static bool ExistAuthData
        {
            get
            {
                return CurrentUserId != default(int) && AuthToken != null;
            }
        }

        private static string _authToken;
        public static string AuthToken
        {
            get { return _authToken; }
            set
            {
                _authToken = value;
                Settings.Authentification.SessionToken = _authToken;
                AuthHeader = new AuthHeader(_authToken);
            }
        }

        private static int _currentUserId;
        public static int CurrentUserId
        {
            get { return _currentUserId; }
            set
            {
                _currentUserId = value;
                Settings.Authentification.CurrentUserId = _currentUserId;
            }
        }
    }


    public class LocalSettings : ILocalSettings
    {
        public T GetValue<T>(string key)
        {
            if (ApplicationData.Current.LocalSettings.Values.ContainsKey(key))
                return (T)ApplicationData.Current.LocalSettings.Values[key];

            return default(T);
        }

        public void SetValue(string key, object value)
        {
            if (value == null)
                ApplicationData.Current.LocalSettings.Values.Remove(key);

            ApplicationData.Current.LocalSettings.Values[key] = value;
        }
    }

    public interface ILocalSettings
    {
        T GetValue<T>(string key);
        void SetValue(string key, object value);
    }

    public static class Settings
    {
        private static readonly ILocalSettings _settings;

        static Settings()
        {
            _settings = new LocalSettings();
        }

        public static class Authentification
        {
            private const string CurrentUserKey = "CurrentUserId";
            public static int CurrentUserId
            {
                get { return _settings.GetValue<int>(CurrentUserKey); }
                set { _settings.SetValue(CurrentUserKey, value); }
            }

            private const string SessionTokenKey = "SessionToken";
            public static string SessionToken
            {
                get { return _settings.GetValue<string>(SessionTokenKey); }
                set { _settings.SetValue(SessionTokenKey, value); }
            }
        }
    }

当我的应用程序启动时，我尝试检查 AppUser 中的 ExistAuthData

if (!AppUser.ExistAuthData)
            {
                ...
            }

它让我例外：

“AppUser.ExistAuthData”引发了“System.TypeInitializationException”类型的异常

但是，当我尝试在AppUser.ExistAuthData一切正常之前获得价值时：

var temp = ApplicationData.Current.LocalSettings.Values.ContainsKey("Anykey");
if (!AppUser.ExistAuthData)

为什么会这样？

UPD

 at System.StubHelpers.StubHelpers.GetWinRTFactoryObject(IntPtr pCPCMD)
   at Windows.Storage.ApplicationData.get_Current()
   at EventsNotifier.Helpers.LocalSettings.GetValue[T](String key) in e:\New projects\Events\EventsNotifier\EventsNotifier\Helpers\Settings.cs:line 9
   at EventsNotifier.Helpers.Settings.Authentification.get_SessionToken() in e:\New projects\Events\EventsNotifier\EventsNotifier\Helpers\Settings.cs:line 70
   at EventsNotifier.Helpers.AppUser.RestorePreviewUserState() in e:\New projects\Events\EventsNotifier\EventsNotifier\Helpers\AppUser.cs:line 13
   at EventsNotifier.Helpers.AppUser..cctor() in e:\New projects\Events\EventsNotifier\EventsNotifier\Helpers\AppUser.cs:line 8
4

1 回答 1

1

我尝试重现您的问题，但我只能在调试时重现它：

  • 即使AppUser.ExistAuthData是构造函数中的第一次调用，App只要我没有在调用之前放置任何断点，它就可以正常工作。
  • 如果我在调用之前放置断点并将鼠标悬停在AppUser.ExistAuthData属性上，我设法使用完全相同的堆栈跟踪重现您的错误。

原因似乎是，如果您LocalSettings在主线程停止时尝试初始化（第一次调用），它会引发异常（即使在调试器工具提示中也可以看到）。一旦发生这种情况，就无法再使用AppUser类，因为异常是从其静态构造函数中抛出的，该构造函数仅被调用一次，并且在以后任何尝试访问它时都会重新抛出相同的异常。几年前我已经在博客上写过这种行为。

如果您LocalSettings在该调用之前访问，则您已经对其进行了初始化，以确保即使主线程停止，将来访问它的尝试也不会失败。这样，即使您将鼠标悬停在调试器中的属性上，一切正常。

于 2013-05-03T09:48:16.230 回答