ASP.NET MVC使用AuthenticationAttribute验证登录

首先，添加一个类AuthenticationAttribute，该类继承AuthorizeAttribute，如下：

using System.Web;
using System.Web.Mvc;

namespace Zhong.Web
{
    public class AuthenticationAttribute : AuthorizeAttribute
    {
        public override void OnAuthorization(AuthorizationContext filterContext)
        {
            //base.OnAuthorization(filterContext);
            //如果控制器没有加AllowAnonymous特性或者Action没有加AllowAnonymous特性才检查
            if (!filterContext.ActionDescriptor.IsDefined(typeof(AllowAnonymousAttribute),true) && !filterContext.ActionDescriptor.ControllerDescriptor.IsDefined(typeof(AllowAnonymousAttribute),true))
            {
                //此处写判断是否登录的逻辑代码
                //这里使用cookie来判断是否登录，为了简单说明特性的使用方式，cookie记录的是用户名和明文密码(实际当中需要经过诸如加密等处理)
                HttpCookie cookie = filterContext.HttpContext.Request.Cookies["Member"];
                if (!(cookie!=null && cookie.Values["name"] == "test" && cookie.Values["pass"] == "123"))
                {
                    filterContext.Result = new RedirectResult("/Member/Login");
                }
            }
        }
    }
}

在MemberControll中加上特性Authentication，Member控制器下有三个Action方法，一个是首页Index，一个是登录页Login，一个是处理Post方式的登录页Login，Index对应的视图代码如下：

@{
    ViewBag.Title = "Index";
}

<h2>这是会员中心</h2>

Login对应的视图代码如下：

@{
    ViewBag.Title = "Login";
}

<h2>会员登录</h2>
@using (Html.BeginForm())
{
    <label>用户名：</label><input type="text" name="name" /><br />
    <label>密码：</label><input type="password" name="password" /><br />
    <input type="submit" value="登录" /> 
}

当没有登录直接访问Member/Index时，会跳转到Login。当输入正确的用户名密码登录时，会跳转到Index页面。

完整的MemberController代码如下：

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

namespace Zhong.Web.Controllers
{
    [Authentication]
    public class MemberController : Controller
    {
        // GET: Member
        public ActionResult Index()
        {
            return View();
        }
        [AllowAnonymous]
        public ActionResult Login()
        {
            return View();
        }
        [AllowAnonymous]
        [HttpPost]
        public ActionResult Login(string name,string password)
        {
            //这里为了简单演示一下登录的判断，主要是验证AuthenticationAttribute的作用，实际的运用中可能要查询数据库、
            //密码判断需要加密处理等
            if (name == "test" && password == "123")
            {
                HttpCookie cookie = new HttpCookie("Member");
                cookie.Values["name"] = "test";
                cookie.Values["pass"] = "123";
                Response.Cookies.Add(cookie);
                return RedirectToAction("Index");
            }
            return View();
        }
    }
}

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

namespace Zhong.Web.Controllers
{
    [Authentication]
    public class MemberController : Controller
    {
        // GET: Member
        public ActionResult Index()
        {
            return View();
        }
        [AllowAnonymous]
        public ActionResult Login()
        {
            return View();
        }
        [AllowAnonymous]
        [HttpPost]
        public ActionResult Login(string name,string password)
        {
            //这里为了简单演示一下登录的判断，主要是验证AuthenticationAttribute的作用，实际的运用中可能要查询数据库、
            //密码判断需要加密处理等
            if (name == "test" && password == "123")
            {
                HttpCookie cookie = new HttpCookie("Member");
                cookie.Values["name"] = "test";
                cookie.Values["pass"] = "123";
                Response.Cookies.Add(cookie);
                return RedirectToAction("Index");
            }
            return View();
        }
    }
}

特别说明：由于控制器使用了Authentication特性，所以请求其下的所有Action都要先通过授权/登录 验证，Login是登录页面，访问这个页面一般是没有登录的状态，所以需要允许匿名访问，于是加了[AllowAnonymous]

 上面的AuthorizationAttribute的另一种写法是继承FilterAttribute 并实现接口IAuthorizationFilter，方式与系统的AuthorizeAttribute类似，

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

namespace Zhong.Web
{
    public class TestAttribute : FilterAttribute, IAuthorizationFilter
    {
        public void OnAuthorization(AuthorizationContext filterContext)
        {
            //throw new NotImplementedException();
            //TODO: 此处写需要实现登录验证的代码

        }
    }
}

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

namespace Zhong.Web
{
    public class TestAttribute : FilterAttribute, IAuthorizationFilter
    {
        public void OnAuthorization(AuthorizationContext filterContext)
        {
            //throw new NotImplementedException();
            //TODO: 此处写需要实现登录验证的代码

        }
    }
}