.NetCore使用过滤器实现登录权限认证的方法小结

/// <summary>
    /// 自定义行为过滤器，实现登录及权限的验证
    /// </summary>
    public class SystemAuthorizeFilter : IActionFilter
    {
        public void OnActionExecuted(ActionExecutedContext context)
        {
            //throw new NotImplementedException();
        }

        /// <summary>
        /// 在执行控制器中的Action方法之前执行该方法  判断当前用户是否登录
        /// </summary>
        /// <param name="context"></param>
        public void OnActionExecuting(ActionExecutinGContext context)
        {　　　　　　　 //排除可以匿名访问的  未登录时
            if (HasAllow(context) == false && context.HttpContext.Session.GetString("User") == null)
            {
                bool isajax = IsAjax(context.HttpContext.Request);

                //如果是Ajax请求自定义返回JSON
                if (isAjax)
                {
                    context.Result = new jsonResult(new { Code = 401, Msg = "登录已失效，请重新登录2！" }) { 
                        StatusCode=StatusCodes.Status401Unauthorized
                    };
                }
                else
                {
                    ContentResult Content = new ContentResult();
                    Content.Content = "<script type='text/javascript'>alert('登录已失效，请重新登录！'); top.location.href='/Login/Login';</script>";
                    Content.ContentType = "text/html;charset=utf-8";
                    context.Result = Content;
                }
            }
        }
        /// <summary>
        /// 排除掉控制器不需要鉴权  即加[AllowAnonymous]特性的无需鉴权
        /// </summary>
        /// <param name="context"></param>
        /// <returns></returns>
        public static bool HasAllow(ActionExecutingContext context)
        {
            var filters = context.Filters;
            if (filters.OfType<IAllowAnonymousFilter>().Any())
            {
                return true;
            }
            var endpoint = context.HttpContext.GetEndpoint();
            return endpoint?.Metadata?.GetMetadata<IAllowAnonymous>() != null;
        }

        /// <summary>
        /// 判断是否是Ajax请求
        /// </summary>
        /// <param name="req"></param>
        /// <returns></returns>
        public static bool IsAjax(HttpRequest req)
        {
            bool result = false;
            var xreq = req.Headers.ContainsKey("x-requested-with");
            if (xreq)
            {
                result = req.Headers["x-requested-with"] == "XMLHttpRequest";
            }
            return result;
        }
    }

//配置系统过滤器
            services.AddControllersWithViews().AddmvcOptions(options =>
            {
                //自定义行为过滤器的方式，验证是否登录及用户权限
                options.Filters.Add<SystemAuthorizeFilter>();
            }).AddNewtonsoftJson(options=> {
                //全局日期格式化
                options.SerializerSettings.DateFORMatString = "yyyy-MM-dd HH:mm:ss";
                //返回的Json大小写原样输出
                options.SerializerSettings.ContractResolver = new DefaultContractResolver();
            });

$.ajax({
            type: "POST",
            data: "",
            async: false,
            dataType: "json",
            url: "",
            beforeSend: function () {
            },
            success: function (data) {
                if (data.Code != null && data.Code != "undefined" && data.Code == 401) {　　　　　　　　　　　　alert('登录已失效，请重新登录！'); top.location.href='/Login/Login';　　　　　　　　　 }                 console.log(data);             },             complete: function () { },             error: function (data) { }         });

/// <summary>
    /// 自定义身份验证过滤器，实现登录及权限的验证
    /// </summary>
    public class CustomAuthorizeFilter : IAuthorizationFilter
    {
        public void OnAuthorization(AuthorizationFilterContext context)
        {
            //如果需要授权 但未登录
            if (HasAllowAnonymous(context) == false && context.HttpContext.Session.GetString("User") == null)
            {
                bool isAjax = IsAjax(context.HttpContext.Request);

                //如果是Ajax请求自定义返回json
                if (isAjax)
                {
                    context.Result = new JsonResult(new { Code = 401, Msg = "登录已失效，请重新登录2！" })
                    {
                        StatusCode = StatusCodes.Status401Unauthorized
                    };
                }
                else
                {
                    ContentResult Content = new ContentResult();
                    Content.Content = "<script type='text/javascript'> alert('登录已失效，请重新登录！'); top.location.href='/Login/Login'; </script>";
                    Content.ContentType = "text/html;charset=utf-8";
                    context.Result = Content;
                }               
            }
        }

        /// <summary>
        /// 排除掉控制器不需要鉴权的 
        /// </summary>
        /// <param name="context"></param>
        /// <returns></returns>
        private static bool HasAllowAnonymous(AuthorizationFilterContext context)
        {
            var filters = context.Filters;
            if (filters.OfType<IAllowAnonymousFilter>().Any())
            {
                return true;
            }
            var endpoint = context.HttpContext.GetEndpoint();
            return endpoint?.Metadata?.GetMetadata<IAllowAnonymous>() != null;
        }
        /// <summary>
        /// 判断是否是Ajax请求
        /// </summary>
        /// <param name="req"></param>
        /// <returns></returns>
        public static bool IsAjax(HttpRequest req)
        {
            bool result = false;
            var xreq = req.Headers.ContainsKey("x-requested-with");
            if (xreq)
            {
                result = req.Headers["x-requested-with"] == "XMLHttpRequest";
            }
            return result;
        }

    }

/// <summary>
        /// 在执行控制器中的Action方法之前执行该方法  判断当前用户是否登录
        /// </summary>
        /// <param name="context"></param>
        public override void OnActionExecuting(ActionExecutingContext context)
        {
            if (context.HttpContext.Session.GetString("User")==null)
            {
                //context.Result = Redirect("/Login/Login");

                ContentResult Content = new ContentResult();
                Content.Content= "<script type='text/javascript'>alert('登录已失效，请重新登录！');top.location.href='/Login/Login'</script>";
                Content.ContentType = "text/html;charset=utf-8";
                context.Result = Content;

                return;
            }
        }