1 // Summary:
 2     //     Represents an attribute that is used to restrict access by callers to an
 3     //     action method.
 4     [AttributeUsage(AttributeTargets.Class | AttributeTargets.Method, Inherited = true, AllowMultiple = true)]
 5     public class AuthorizeAttribute : FilterAttribute, IAuthorizationFilter
 6     {
 7         // Summary:
 8         //     Initializes a new instance of the System.Web.Mvc.AuthorizeAttribute class.
 9         public AuthorizeAttribute();
10 
11         // Summary:
12         //     Gets or sets the user roles.
13         //
14         // Returns:
15         //     The user roles.
16         public string Roles { get; set; }
17         //
18         // Summary:
19         //     Gets the unique identifier for this attribute.
20         //
21         // Returns:
22         //     The unique identifier for this attribute.
23         public override object TypeId { get; }
24         //
25         // Summary:
26         //     Gets or sets the authorized users.
27         //
28         // Returns:
29         //     The authorized users.
30         public string Users { get; set; }
31 
32         // Summary:
33         //     When overridden, provides an entry point for custom authorization checks.
34         //
35         // Parameters:
36         //   httpContext:
37         //     The HTTP context, which encapsulates all HTTP-specific information about
38         //     an individual HTTP request.
39         //
40         // Returns:
41         //     true if the user is authorized; otherwise, false.
42         //
43         // Exceptions:
44         //   System.ArgumentNullException:
45         //     The httpContext parameter is null.
46         protected virtual bool AuthorizeCore(HttpContextBase httpContext);
47         //
48         // Summary:
49         //     Processes HTTP requests that fail authorization.
50         //
51         // Parameters:
52         //   filterContext:
53         //     Encapsulates the information for using System.Web.Mvc.AuthorizeAttribute.
54         //     The filterContext object contains the controller, HTTP context, request context,
55         //     action result, and route data.
56         protected virtual void HandleUnauthorizedRequest(AuthorizationContext filterContext);
57         //
58         // Summary:
59         //     Called when a process requests authorization.
60         //
61         // Parameters:
62         //   filterContext:
63         //     The filter context, which encapsulates information for using System.Web.Mvc.AuthorizeAttribute.
64         //
65         // Exceptions:
66         //   System.ArgumentNullException:
67         //     The filterContext parameter is null.
68         public virtual void OnAuthorization(AuthorizationContext filterContext);
69         //
70         // Summary:
71         //     Called when the caching module requests authorization.
72         //
73         // Parameters:
74         //   httpContext:
75         //     The HTTP context, which encapsulates all HTTP-specific information about
76         //     an individual HTTP request.
77         //
78         // Returns:
79         //     A reference to the validation status.
80         //
81         // Exceptions:
82         //   System.ArgumentNullException:
83         //     The httpContext parameter is null.
84         protected virtual HttpValidationStatus OnCacheAuthorization(HttpContextBase httpContext);
85     }

 1 public class LoginFilterAttribute:AuthorizeAttribute
 2     {
 3 
 4         private static string formsCookieName = FormsAuthentication.FormsCookieName;
 5 
 6         public override void OnAuthorization(AuthorizationContext filterContext)
 7         {
 8            HttpCookie formsCookie =
 9                 System.Web.CookieManager.GetCookie(formsCookieName);
10             if (formsCookie == null)
11             {
12                 //页面Cookie过期后返回登录页面
13                 RedirectToLoginPage(filterContext);
14                 return;
15             }
16  
17             bool autenticated = HttpContext.Current.User.Identity.IsAuthenticated;
18 
19             //一旦发现身份不合法就作相应的处理.
20             if (!autenticated )
21             {
22                 //redirect to login
23                 RedirectToLoginPage(filterContext);
24                 return;
25             }
26             //if success add login data to context
27         }
28            private static void RedirectToLoginPage(AuthorizationContext filterContext)
29         {
30             if (filterContext.HttpContext.Request.IsAjaxRequest())
31             {
32                 filterContext.Result = new JsonResult() 
33                 { 
34                     Data = http://www.mamicode.com/new {
35                         status = "error",
36                         message = "Unauthorized_Message"
37                     },
38                     JsonRequestBehavior= JsonRequestBehavior.AllowGet
39                 };
40                 return;
41             }
42 else
43 {
44          //返回登录页面的相关处理..........
45 }
}

1     [LoginFilter]//此处就是我们上面定义的LoginFilterAttribute
2     public abstract partial class BaseController : Controller
3     {
4         public BaseController(){ 
5         
6         }
7       //........其他相关处理
8     }

1 Public Class LoginController：BaseController
2 {
3      Public ActionResult Index（）
4     {
5       //........
6        return  View();
7     }
8 }