1.在MVC项目中添加用户类，可以根据实际项目需求添加必要属性

public class UserData
    {
        /// <summary>
        /// ID
        /// </summary>
        public int UserId { get; set; }

        /// <summary>
        /// 用户名
        /// </summary>
        public string UserName { get; set; }

        /// <summary>
        /// 角色ID列表
        /// </summary>
        public List<int> Roles { get; set; }
    }

2.添加类Principal实现IPrincipal接口

    public class Principal : IPrincipal
    {
        public IIdentity Identity { get; private set;}

        public UserData Account { get; set; }

        /// <summary>
        /// 构造函数
        /// </summary>
        /// <param name="ticket"></param>
        /// <param name="account"></param>
        public Principal(FormsAuthenticationTicket ticket, UserData account)
        {
            if (ticket == null)
                throw new ArgumentNullException("ticket");
            if (account == null)
                throw new ArgumentNullException("UserData");

            this.Identity = new FormsIdentity(ticket);
            this.Account = account;
        }

        public bool IsInRole(string role)
        {
            if (string.IsNullOrEmpty(role))
                return true;
            if (this.Account == null || this.Account.Roles == null)
                return false;
            return role.Split(‘,‘).Any(q => Account.Roles.Contains(int.Parse(q)));
        }
    }

IPrincipal接口有对象Identity已经需要实现验证角色方法IsInRole()。在我们的实现类中添加了"用户信息(UserData)"属性Account。

构造函数中进行了初始化，第一个对象为Form验证的票据对象，下面ticket会携带用户信息一起保存进cookie中。

3.创建存储cookie和读取cookie的类

    /// <summary>
    /// 写入cookie和读取cookie
    /// </summary>
    public class HttpFormsAuthentication
    {
        //将用户信息通过ticket加密保存到cookie
        public static void SetAuthenticationCoolie(UserData account, int rememberDay = 0)
        {
            if (account == null)
                throw new ArgumentNullException("account");

            //序列化account对象
            string accountJson = JsonConvert.SerializeObject(account);
            //创建用户票据
            var ticket = new FormsAuthenticationTicket(1, account.UserName, DateTime.Now, DateTime.Now.AddDays(rememberDay), false, accountJson);
            //加密
            string encryptAccount = FormsAuthentication.Encrypt(ticket);

            //创建cookie
            var cookie = new HttpCookie(FormsAuthentication.FormsCookieName, encryptAccount)
            {
                HttpOnly = true,
                Secure = FormsAuthentication.RequireSSL,
                Domain = FormsAuthentication.CookieDomain,
                Path = FormsAuthentication.FormsCookiePath
            };

            if (rememberDay > 0)
                cookie.Expires = DateTime.Now.AddDays(rememberDay);

            //写入Cookie
            HttpContext.Current.Response.Cookies.Remove(cookie.Name);
            HttpContext.Current.Response.Cookies.Add(cookie);
        }

        //获取cookie并解析出用户信息
        public static Principal TryParsePrincipal(HttpContext context)
        {
            if (context == null)
                throw new ArgumentNullException("context");
            HttpRequest request = context.Request;
            HttpCookie cookie = request.Cookies[FormsAuthentication.FormsCookieName];
            if (cookie == null || string.IsNullOrEmpty(cookie.Value))
            {
                return null;
            }
            //解密coolie值
            FormsAuthenticationTicket ticket = FormsAuthentication.Decrypt(cookie.Value);

            UserData account = JsonConvert.DeserializeObject<UserData>(ticket.UserData);
            return new Principal(ticket, account);
        }

    }

存储cookie时将用户信息序列化后的字符串accountJson由ticket其携带加密后保存入cookie中，具体的accountJson被赋值给FormsAuthenticationTicket的UserData属性。

可看到解析时将ticket.UserData反序列化后得到了原始的用户信息对象，然后生成Principal对象。

解析cookie得到Principal对象的方法TryParsePrincipal，下面会在发起请求时用到，而返回的Principal对象被赋值给HttpContext.User。

4.在Global.asax中注册Application_PostAuthenticateRequest事件，保证权限验证前将cookie中的用户信息取出赋值给User

protected void Application_PostAuthenticateRequest(object sender, System.EventArgs e)
        {
            HttpContext.Current.User =
                HttpFormsAuthentication.TryParsePrincipal(HttpContext.Current);
        }

5.集成AuthorizeAttribute特性类并重写AuthorizeCore，HandleUnauthorizedRequest方法

    public class FormAuthorizeAttribute : AuthorizeAttribute
    {
        /// <summary>
        /// 先进入此方法，此方法中会调用 AuthorizeCore 验证逻辑，验证不通过会调用 HandleUnauthorizedRequest 方法
        /// </summary>
        /// <param name="filterContext"></param>
        public override void OnAuthorization(AuthorizationContext filterContext)
        {
            base.OnAuthorization(filterContext);
        }

        /// <summary>
        /// 权限验证
        /// </summary>
        /// <param name="httpContext"></param>
        /// <returns></returns>
        protected override bool AuthorizeCore(HttpContextBase httpContext)
        {
            var user = httpContext.User as Principal;
            if (user != null)
                return user.IsInRole(base.Roles);
            return false;
        }

        protected override void HandleUnauthorizedRequest(AuthorizationContext filterContext)
        {
            //验证不通过，直接跳转到相应页面，注意：如果不是哟娜那个以下跳转，则会继续执行Action方法
            filterContext.Result = new RedirectResult("~/Login/Index");
        }
    }

AuthorizeCore与HandleUnauthorizedRequest方法均是在方法OnAuthorization中调用，AuthorizeCore验证不通过才会调用HandleUnauthorizedRequest方法。

将验证代码在AuthorizeCore中实现，验证不通过的逻辑在HandleUnauthorizedRequest方法中实现。

6.添加LoginController实现登录逻辑

namespace MVCAuthorizeTest.Controllers
{
    public class LoginController : Controller
    {
        [AllowAnonymous]
        // GET: Login
        public ActionResult Index(string returnUrl)
        {
            ViewBag.ReturnUrl = returnUrl;
            return View();
        }

        [HttpPost]
        [AllowAnonymous]
        public ActionResult Index(string name, string password, bool rememberMe, string returnUrl)
        {
            var account = new UserData()
            {
                UserName = name,
                UserId = 110,
                Roles = new List<int>() { 1, 2, 3 }
            };
            HttpFormsAuthentication.SetAuthenticationCoolie(account, rememberMe ? 7 : 0);
            if (Url.IsLocalUrl(returnUrl) && returnUrl.Length > 1 && returnUrl.StartsWith("/") && !returnUrl.StartsWith("//") && !returnUrl.StartsWith("/\\"))
            {
                return Redirect(returnUrl);
            }
            else
            {
                return RedirectToAction("Index", "Home");
            }
        }

        // POST: /Account/LogOff
        [HttpPost]
        public ActionResult LogOff()
        {
            System.Web.Security.FormsAuthentication.SignOut();
            return RedirectToAction("Index", "Home");
        }
    }
}

7.对需要验证的controller或action添加特性标签

    [FormAuthorize(Roles = "1,2")]
    public class HomeController : Controller
    {
        [FormAuthorize]
        public ActionResult Index()
        {
            return View();
        }
    }

如图

8.在添加FilterConfig中添加全局注册filter，减少每个action分别设置。如果有不需要验证的页面，添加[AllowAnonymous]特性即可

    public class FilterConfig
    {
        public static void RegisterGlobalFilters(GlobalFilterCollection filters)
        {
            filters.Add(new HandleErrorAttribute());
            //全局注册filter
            filters.Add(new FormAuthorizeAttribute());
        }
    }