using System.Collections.Generic;
using System.Web.Mvc;
using System.Web.Routing;

namespace MvcApplication1.Controllers
{
    public class BaseController<TModel> : Controller
    {

        private const string loginSession = "LoginSession";
        private const string shoppingCartSession = "ShoppingCartSession";
        private const string errorController = "Error";
        private const string LoginController = "Login";
        private const string LoginAction = "Login";

        //没有登录的跳转到登录页
        protected override void Initialize(RequestContext requestContext)
        {
            base.Initialize(requestContext);
            //如果没有登录，且不是出错和登录控制器就跳转到登录页
            if (!NoNeedSessionController(requestContext) && !HasLoginSession())
            {
                GoToAction(requestContext, Url.Action(LoginAction, LoginController));
            }
        }

        //对哪些不需要依赖缓存的控制器 返回true
        private bool NoNeedSessionController(RequestContext requestContext)
        {
            //从路由数据中取到当前controller的名称
            var c = requestContext.RouteData.Values["controller"].ToString().ToLower();

            //把不需要依赖Session的控制器名称放到列表中
            var noNeedSessionList = new List<string>
            {
                errorController.ToLower(),
                LoginController.ToLower()
            };

            return noNeedSessionList.Contains(c);
        }

        //跳转到某个视图
        private void GoToAction(RequestContext requestContext, string action)
        {
            requestContext.HttpContext.Response.Clear();
            requestContext.HttpContext.Response.Redirect(action);
            requestContext.HttpContext.Response.End();
        }

        //登录的时候判断是否有Session
        protected bool HasLoginSession()
        {
            return Session[loginSession] != null;
        }

        //判断购物车是否有Session
        protected bool HasShoppingCartSession()
        {
            return Session[shoppingCartSession] != null;
        }

        //从Session中获取登录模型的实例
        protected TModel GetLoginModelFromSession()
        {
            return (TModel)this.Session[loginSession];
        }

        //从Session中获取购物车模型的实例
        protected TModel GetShoppingCartModelFromSession()
        {
            return (TModel)this.Session[shoppingCartSession];
        }

        //设置登录Session
        protected void SetLoginSession(TModel loginModel)
        {
            Session[loginSession] = loginModel;
        }

        //设置购物车Session
        protected void SetShoppingCartSession(TModel shoppingCartModel)
        {
            Session[shoppingCartSession] = shoppingCartModel;
        }

        //让登录Session失效
        protected void AbandonLoginSession()
        {
            if (HasLoginSession())
            {
                Session.Abandon();
            }
        }

        //让购物车Session失效
        protected void AbandonShoppingCartSession()
        {
            if (HasShoppingCartSession())
            {
                Session.Abandon();
            }
        }
    }
}

using System.Web.Mvc;
using MvcApplication1.Models;

namespace MvcApplication1.Controllers
{
    public class LoginController : BaseController<LoginModel>
    {
        public ActionResult Index()
        {
            //把登录模型实例保存到Session中
            LoginModel loginModel = new LoginModel();
            SetLoginSession(loginModel);

            //从Session中获取登录模型实例
            LoginModel sessioModel = GetLoginModelFromSession();

            //使登录Session失效
            AbandonLoginSession();
            return View();
        }

    }
}