asp.net mvc 权限过滤和单点登录（禁止重复登录）

1.权限控制使用controller和 action来实现，权限方式有很多种，最近开发项目使用控制控制器方式实现代码如下

     /// <summary>
    /// 用户权限控制
    /// </summary>
    public class UserAuthorize : AuthorizeAttribute
    {

        /// <summary>
        /// 授权失败时呈现的视图
        /// </summary>
        public string AuthorizationFailView { get; set; }

        /// <summary>
        /// 请求授权时执行
        /// </summary>
        /// <param name="filterContext">上下文</param>
        public override void OnAuthorization(AuthorizationContext filterContext)
        {

            // 获取url请求里的 controller 和 action
            string controllerName = filterContext.RouteData.Values["controller"].ToString();
            string actionName = filterContext.RouteData.Values["action"].ToString();

            // 获取用户信息
            UserLoginBaseInfo _userLoginInfo = filterContext.HttpContext.Session[Property.UerLoginSession] as UserLoginBaseInfo;

            //根据请求过来的controller和action去查询可以被哪些角色操作: 这是查询数据库  roleid使用 1,2,3,4格式
            RoleWithControllerAction roleWithControllerAction =
               SampleData.roleWithControllerAndAction.FirstOrDefault(r => r.ControllerName.ToLower() == controllerName.ToLower() && r.ActionName.ToLower() == actionName.ToLower() && r.RoleIds.contails("3"));

            // 有值处理
            if (roleWithControllerAction != null)
            {
                //有权限操作当前控制器和Action的角色id
                this.Roles = roleWithControllerAction.RoleIds;
            }
            else
            {
                //请求失败输出空结果
                filterContext.Result = new EmptyResult();
                //打出提示文字
                HttpContext.Current.Response.Write("对不起,你没有权限操作!");
            }

            base.OnAuthorization(filterContext);
        }

        /// <summary>
        /// 自定义授权检查（返回False则授权失败）
        /// </summary>
        protected override bool AuthorizeCore(HttpContextBase httpContext)
        {
            //if (httpContext.User.Identity.IsAuthenticated)
            //{
            //    string userName = httpContext.User.Identity.Name;    //当前登录用户的用户名
            //    User user = SampleData.users.Find(u => u.UserName == userName);   //当前登录用户对象

            //    if (user != null)
            //    {
            //        Role role = SampleData.roles.Find(r => r.Id == user.RoleId);  //当前登录用户的角色
            //        foreach (string roleid in Roles.Split(','))
            //        {
            //            if (role.Id.ToString() == roleid)
            //                return true;
            //        }
            //        return false;
            //    }
            //    else
            //        return false;
            //}
            //else
            //    return false;     //进入HandleUnauthorizedRequest 

            return true;
        }

        /// <summary>
        /// 处理授权失败的HTTP请求
        /// </summary>
        protected override void HandleUnauthorizedRequest(AuthorizationContext filterContext)
        {
            if (string.IsNullOrWhiteSpace(AuthorizationFailView))
                AuthorizationFailView = "error";

            filterContext.Result = new ViewResult { ViewName = AuthorizationFailView };
        }
    }

二.单点登录方式使用application方式来实现

1.用户登录成功后记录当前信息

         /// <summary>
        /// 限制一个用户只能登陆一次
        /// </summary>
        /// <returns></returns>
        private void GetOnline()
        {
            string UserID = "1";
            Hashtable SingleOnline = (Hashtable)System.Web.HttpContext.Current.Application[Property.Online];
            if (SingleOnline == null)
                SingleOnline = new Hashtable();

            IDictionaryEnumerator idE = SingleOnline.GetEnumerator();
            string strKey = string.Empty;
            while (idE.MoveNext())
            {
                if (idE.Value != null && idE.Value.ToString().Equals(UserID))
                {
                    //already login
                    strKey = idE.Key.ToString();

                    //当前用户已存在移除、
                    SingleOnline.Remove(strKey);
                    System.Web.HttpContext.Current.Application.Lock();
                    System.Web.HttpContext.Current.Application[Property.Online] = SingleOnline;
                    System.Web.HttpContext.Current.Application.UnLock();
                    break;
                }
            }

            //SessionID
            if (!SingleOnline.ContainsKey(Session.SessionID))
            {
                SingleOnline[Session.SessionID] = UserID;
                System.Web.HttpContext.Current.Application.Lock();
                System.Web.HttpContext.Current.Application[Property.Online] = SingleOnline;
                System.Web.HttpContext.Current.Application.UnLock();
            }
        }

2.使用ActionFilter来实现单点登录，每次点击控制器都去查询过滤是否在其它地方登录

   /// <summary>
    /// 用户基础信息过滤器
    /// </summary>
    public class LoginActionFilter : ActionFilterAttribute
    {

        /// <summary>
        /// 初始化地址
        /// </summary>
        public const string Url = "~/Login/Index?error=";

        /// <summary>
        ///  该方法会在action方法执行之前调用
        /// </summary>
        /// <param name="filterContext">上下文</param>
        public override void OnActionExecuting(ActionExecutingContext filterContext)
        {
            // 获取上一级url
            // var url1 = filterContext.HttpContext.Request.UrlReferrer;

            UserLoginBaseInfo _userLogin = filterContext.HttpContext.Session[Property.UerLoginSession] as UserLoginBaseInfo;
            // 用户是否登陆
            if (_userLogin == null)
            {
                filterContext.Result = new RedirectResult(Url + "登陆时间过期,请重新登陆!&url=" + filterContext.HttpContext.Request.RawUrl);
            }
            else
            {
                filterContext.HttpContext.Session.Timeout = 30;
            }

            //判断是否在其它地方登录
            Hashtable singleOnline = (Hashtable)System.Web.HttpContext.Current.Application[Property.Online];

            // 判断当前SessionID是否存在
            if (singleOnline != null && !singleOnline.ContainsKey(HttpContext.Current.Session.SessionID))
                filterContext.Result = new RedirectResult(Url + "你的帐号已在别处登陆，你被强迫下线!");

            base.OnActionExecuting(filterContext);

        }

        /// <summary>
        /// 执行后
        /// </summary>
        /// <param name="filterContext"></param>
        public override void OnResultExecuting(ResultExecutingContext filterContext)
        {

            //记录操作日志，写进操作日志中
            var controllerName = filterContext.RouteData.Values["controller"];
            var actionName = filterContext.RouteData.Values["action"];
            base.OnResultExecuting(filterContext);
        }

3.用户正常退出或则非正常退出处理当前用户信息销毁Session

        /// <summary>
        /// Session销毁
        /// </summary>
        protected void Session_End()
        {
            Hashtable SingleOnline = (Hashtable)Application[Property.Online];
            if (SingleOnline != null && SingleOnline[Session.SessionID] != null)
            {
                SingleOnline.Remove(Session.SessionID);
                Application.Lock();
                Application[Property.Online] = SingleOnline;
                Application.UnLock();
            }
            Session.Abandon();
        }

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