OAuth 2.0如何验证令牌的到期日期

Question

I am using MVC Web API inside MVC project.I use AuthorizeForAPI custom Attribute to valid the token. Everything is working great. My question is how to validate token expiration date so if the the token has expired i will send a message from server tells the user that your token has been expired

public class AuthorizeForAPI : AuthorizeAttribute
{

    public override void OnAuthorization(HttpActionContext actionContext)
    {
        string AccessTokenFromRequest = "";
        if (actionContext.Request.Headers.Authorization != null)
        {
            // get the access token
            AccessTokenFromRequest = actionContext.Request.Headers.Authorization.Parameter;

            var user = HttpContext.Current.User.Identity;
            if (!user.IsAuthenticated)
            {
                actionContext.Response = actionContext.Request.CreateResponse(HttpStatusCode.Unauthorized, "Unauthorized user");

            }
        }
    }
}

Answer 1

using

 AccessTokenExpireTimeSpan = TimeSpan.FromDays(22), //22 day b4 expired

also

     var user = HttpContext.Current.User.Identity;
                    if (!user.IsAuthenticated)
                    {
                        actionContext.Response = actionContext.Request.CreateResponse(HttpStatusCode.Unauthorized, "Unauthorized user");
                    } 
    else
        {    
actionContext.Request.CreateErrorResponse(HttpStatusCode.NonAuthoritativeInformation, "Expired Token"
        }