.NET Core自定义授权过滤器

Question

我正在开发MVC .NET Core 2中的新应用程序，但我必须使用在MVC5中开发的另一个应用程序中使用的现有身份验证和授权。它使用当前用户详细信息调用Web服务以获取用户所在的组和角色的列表，这在GetUserRoles方法中完成。从谷歌搜索来看，与MVC 5相比，现在看起来不同。有人可以帮我实现这个，所以我可以这样使用它：

 [BasicAuthorisation(Roles = "SpecificUser")]

以下是我尝试在.NET Core中实现的过滤器片段：

[AttributeUsage(AttributeTargets.All, AllowMultiple = false, Inherited = true)]
public class BasicAuthorisation : AuthorizeAttribute, IAuthorizationFilter
{
    MemoryCache mc = MemoryCache.Default;
    private ClaimsPrincipal _principal;
    private string _applicationName = "";

    public override void OnAuthorization(AuthorizationContext filterContext)
    {
        bool skipAuthorisation = filterContext.ActionDescriptor.IsDefined(typeof(AllowAnonymousAttribute), true)
            || filterContext.ActionDescriptor.ControllerDescriptor.IsDefined(typeof(AllowAnonymousAttribute), true);

        _principal = HttpContext.Current.User as ClaimsPrincipal;

        if (_principal.Identity == null)
        {
            _principal = Thread.CurrentPrincipal as ClaimsPrincipal;
        }
        _applicationName = System.Configuration.ConfigurationManager.AppSettings["ApplicationName"];

        if (_principal.Identity.IsAuthenticated)
        {
            if (!skipAuthorisation)
            {
                // set userRole cache name
                string userRoleCache = _principal.Identity.Name.Replace(DoubleSlash, string.Empty) + CacheSuffix;

                List<string> userRoles = GetUserRoles(_principal, userRoleCache);

                //get system defined Role groups
                List<string> restrictedRoleGroups = Roles.Split(_doubleBar, StringSplitOptions.RemoveEmptyEntries).Select(r => r.Trim()).ToList();

                // iterate groups for authorisation 
                for (int i = 0; i < restrictedRoleGroups.Count(); i++)
                {
                    List<string> restrictedRoles = restrictedRoleGroups[i].Split(',').Select(r => r.Trim()).ToList();

                    List<string> matchingRoles = (from ur in userRoles
                                                  where (restrictedRoles.Any(mr => ur == mr))
                                                  select ur).ToList();

                    if (matchingRoles.Count().Equals(restrictedRoles.Count()))
                    {
                        _outcome = true;
                    }

                }
            }
            else { _outcome = true; }
        }

        if (_outcome == false)
        {
            filterContext.Result = new RedirectResult("~/Message/Index");
        }
}