ASP.NET MVC的Action拦截器（过滤器）ActionFilter

有时项目要进行客户端请求(action)进行拦截(过滤)验证等业务，可以使用拦截器进行实现，所谓的action拦截器也没有什么的，只是写一个类，继承另一个类（System.Web.Mvc.FilterAttribute）和一个接口(System.Web.Mvc.IActionFilter)，至于什么是拦截器这里就不说了，网上很多关于这方面文章。

假如现在有这样的一个需求：某个action需要登录才能进行访问，可以使用action属性拦截器进行拦截进行验证

多余的不说了直接上代码

写一个拦截器类：

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

 namespace AttributeDemo.Common
 {
     /// <summary>
     /// Action拦截器
     /// </summary>
     public class ActionFilterAttribute : System.Web.Mvc.FilterAttribute, System.Web.Mvc.IActionFilter
     {
         #region 属性
         /// <summary>
         /// 记录是否登陆
         /// </summary>
         public bool IsLogin { get; set; }
         #endregion

         #region 执行action后执行这个方法
         /// <summary>
         /// 执行action后执行这个方法
         /// </summary>
         /// <param name="filterContext"></param>
         void System.Web.Mvc.IActionFilter.OnActionExecuted(System.Web.Mvc.ActionExecutedContext filterContext)
         {

         }
         #endregion

         #region 执行action前执行这个方法
         /// <summary>
         /// 执行action前执行这个方法
         /// </summary>
         /// <param name="filterContext"></param>
         void System.Web.Mvc.IActionFilter.OnActionExecuting(System.Web.Mvc.ActionExecutingContext filterContext)
         {

             if (!this.IsLogin)  //未登陆 重定向 到登陆页面
             {
                 if (filterContext.HttpContext.Request.IsAjaxRequest())   //判断是否ajax请求
                 {

                     filterContext.Result = new System.Web.Mvc.JsonResult() { Data = new { statusCode =  }, ContentEncoding = System.Text.Encoding.UTF8, JsonRequestBehavior = JsonRequestBehavior.AllowGet, ContentType = "json" };
                     return;
                 }
                 else  //验证不通过
                 {
                     //filterContext.Result = new RedirectToRouteResult(new System.Web.Routing.RouteValueDictionary(new { controller = "ActionFilterTest", action = "Login" }));  //重定向
                     //filterContext.Result = new RedirectToRouteResult(new System.Web.Routing.RouteValueDictionary(new Dictionary<string, object>() { { "controller", "ActionFilterTest" }, { "action", "Login" } }));   //重定向

                     //filterContext.Result = new System.Web.Mvc.RedirectToRouteResult("Default", new System.Web.Routing.RouteValueDictionary(new Dictionary<string, object>() { { "controller", "ActionFilterTest" }, { "action", "Login" } }));    //重定向

                     //filterContext.Result = new System.Web.Mvc.RedirectToRouteResult("Default", new System.Web.Routing.RouteValueDictionary(new Dictionary<string, object>() { { "controller", "ActionFilterTest" }, { "action", "Login" } }),true);  //重定向

                     filterContext.Result = new System.Web.Mvc.RedirectToRouteResult("MyRoute", new System.Web.Routing.RouteValueDictionary(new Dictionary<string, object>() { { "controller", "ActionFilterTest" }, { "action", "Login" } }), true);    //重定向
                     return;
                 }

             }

         }
         #endregion

     }
 }

请求的控制器类：

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

 namespace AttributeDemo.Controllers
 {
     /// <summary>
     /// 测试Action拦截器
     /// </summary>
     public class ActionFilterTestController : Controller
     {
         //
         // GET: /ActionFilterTest/

         /// <summary>
         /// 测试action拦截器
         /// </summary>
         /// <returns></returns>
         [AttributeDemo.Common.ActionFilter(IsLogin = false)]
         public ActionResult Test()
         {
             return View();
         }

         public ActionResult Login()
         {
             return View();
         }

         [AttributeDemo.Common.ActionFilter(IsLogin = true)]
         public ActionResult Index()
         {
             return View();
         }
     }
 }

Global.asax类：

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

 namespace AttributeDemo
 {
     // 注意: 有关启用 IIS6 或 IIS7 经典模式的说明，
     // 请访问 http://go.microsoft.com/?LinkId=9394801

     public class MvcApplication : System.Web.HttpApplication
     {
         public static void RegisterGlobalFilters(GlobalFilterCollection filters)
         {
             filters.Add(new HandleErrorAttribute());
         }

         public static void RegisterRoutes(RouteCollection routes)
         {
             routes.IgnoreRoute("{resource}.axd/{*pathInfo}");

             routes.MapRoute(
                 "Default", // 路由名称
                 "{controller}/{action}/{id}", // 带有参数的 URL
                 new { controller = "Home", action = "Index", id = UrlParameter.Optional } // 参数默认值
             );
             routes.MapRoute(
                 "MyRoute", // 路由名称
                 "{controller}/{action}/{id}", // 带有参数的 URL
                 new { controller = "ActionFilterTest", action = "Login", id = UrlParameter.Optional } // 参数默认值
             );
         }

         protected void Application_Start()
         {
             AreaRegistration.RegisterAllAreas();

             RegisterGlobalFilters(GlobalFilters.Filters);
             RegisterRoutes(RouteTable.Routes);
         }
     }
 }

注意：拦截器也可以写在控制器类属性上，写在控制器类上表示拦截该控制器下所有action，如果写在action只是拦截当前action有效

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

namespace AttributeDemo.Controllers
{
    /// <summary>
    /// 测试Action拦截器
    /// </summary>
    [AttributeDemo.Common.ActionFilter(IsLogin = false)]
    public class ActionFilterTestController : Controller
    {
        //
        // GET: /ActionFilterTest/
    }
}