namespace MVCCommonAuth
{
  #region 功能说明
  // 举个例子：一个网站有用户系统、商家系统、网站后台3个系统
  //可以分3个userType, user ,shop , system
  //网站后台一般都有角色，如admin,employee
  //那么网站的角色就有 user,shop,admin,employee,但是admin和employee在一个客户端是不能同时登陆的，所以他们是同一类用户（system）
  #endregion

  public enum UserType
  {
    User,
    Shop,
    System
  }

  [Serializable]
  public class LoginUser
  {
    private static string DESKEY = DateTime.Now.ToString(\"1234MMdd\");
    public int ID { get; set; }
    public string UserName { get; set; }
    public string Roles { get; set; }
    public DateTime Expires { get; set; }

    public readonly static string CookieNamePrefix = \"authcookie\";

    public void Login(string userType, string domain = null, string path = null)
    {
      var keyName = CookieNamePrefix + userType;
      var json = JsonConvert.SerializeObject(this);
      var value = EncryptString(json, DESKEY);

      HttpCookie cookie = new HttpCookie(keyName, value);
      cookie.Expires = Expires;
      if (!string.IsNullOrWhiteSpace(domain))
      {
        cookie.Domain = domain;
      }
      if (path != null)
      {
        cookie.Path = path;
      }
      HttpContext.Current.Items[keyName] = this;
      HttpContext.Current.Response.Cookies.Add(cookie);
    }


    /// <summary>
    /// 从cookie读取用户信息
    /// </summary>
    /// <param name=\"cookieName\"></param>
    private static LoginUser BuildUser(string keyName)
    {
      var cookie = HttpContext.Current.Request.Cookies[keyName];
      if (cookie != null && !string.IsNullOrEmpty(cookie.Value))
      {
        try
        {
          var json = DecryptString(cookie.Value, DESKEY);
          var loginuser = JsonConvert.DeserializeObject<LoginUser>(json);
          if (loginuser != null)
          {
            if (loginuser.Expires >= DateTime.Now)
            {
              return loginuser;
            }
          }
        }
        catch
        {
          //do nothing
        }
      }
      return null;
    }

    public static LoginUser GetUser(string userType)
    {
      var keyName = CookieNamePrefix + userType;
      if (!HttpContext.Current.Items.Contains(keyName))
      {
        var user = BuildUser(keyName);
        HttpContext.Current.Items[keyName] = user;
        return user;
      }
      else
      {
        return HttpContext.Current.Items[keyName] as LoginUser;
      }
    }

    public static int GetUserID(string userType)
    {
      var user = GetUser(userType);
      if (user != null)
        return user.ID;
      return 0;
    }

    /// <summary>
    /// 退出cookie登录
    /// </summary>
    public static void Logout(string userType)
    {
      var keyName = CookieNamePrefix + userType;

      HttpCookie cookie = new HttpCookie(keyName, string.Empty);
      cookie.Expires = DateTime.Now.AddMonths(-1);
      HttpContext.Current.Response.Cookies.Add(cookie);
    }


    #region 字符串加密

    /// <summary>  
    /// 利用DES加密算法加密字符串（可解密）  
    /// </summary>  
    /// <param name=\"plaintext\">被加密的字符串</param>  
    /// <param name=\"key\">密钥（只支持8个字节的密钥）</param>  
    /// <returns>加密后的字符串</returns>  
    private static string EncryptString(string plaintext, string key)
    {
      //访问数据加密标准(DES)算法的加密服务提供程序 (CSP) 版本的包装对象  
      DESCryptoServiceProvider des = new DESCryptoServiceProvider();
      des.Key = ASCIIEncoding.ASCII.GetBytes(key);　//建立加密对象的密钥和偏移量  
      des.IV = ASCIIEncoding.ASCII.GetBytes(key);　 //原文使用ASCIIEncoding.ASCII方法的GetBytes方法  

      byte[] inputByteArray = Encoding.Default.GetBytes(plaintext);//把字符串放到byte数组中  

      MemoryStream ms = new MemoryStream();//创建其支持存储区为内存的流　  
      //定义将数据流链接到加密转换的流  
      CryptoStream cs = new CryptoStream(ms, des.CreateEncryptor(), CryptoStreamMode.Write);
      cs.Write(inputByteArray, 0, inputByteArray.Length);
      cs.FlushFinalBlock();
      //上面已经完成了把加密后的结果放到内存中去  
      StringBuilder ret = new StringBuilder();
      foreach (byte b in ms.ToArray())
      {
        ret.AppendFormat(\"{0:X2}\", b);
      }
      ret.ToString();
      return ret.ToString();
    }
    /// <summary>  
    /// 利用DES解密算法解密密文（可解密）  
    /// </summary>  
    /// <param name=\"ciphertext\">被解密的字符串</param>  
    /// <param name=\"key\">密钥（只支持8个字节的密钥，同前面的加密密钥相同）</param>  
    /// <returns>返回被解密的字符串</returns>  
    private static string DecryptString(string ciphertext, string key)
    {
      try
      {
        DESCryptoServiceProvider des = new DESCryptoServiceProvider();

        byte[] inputByteArray = new byte[ciphertext.Length / 2];
        for (int x = 0; x < ciphertext.Length / 2; x++)
        {
          int i = (Convert.ToInt32(ciphertext.Substring(x * 2, 2), 16));
          inputByteArray[x] = (byte)i;
        }

        des.Key = ASCIIEncoding.ASCII.GetBytes(key);　//建立加密对象的密钥和偏移量，此值重要，不能修改  
        des.IV = ASCIIEncoding.ASCII.GetBytes(key);
        MemoryStream ms = new MemoryStream();
        CryptoStream cs = new CryptoStream(ms, des.CreateDecryptor(), CryptoStreamMode.Write);

        cs.Write(inputByteArray, 0, inputByteArray.Length);

        cs.FlushFinalBlock();

        //建立StringBuild对象，createDecrypt使用的是流对象，必须把解密后的文本变成流对象  
        StringBuilder ret = new StringBuilder();

        return System.Text.Encoding.Default.GetString(ms.ToArray());
      }
      catch (Exception)
      {
        return \"error\";
      }
    }

    #endregion
  }
}

    [HttpPost]
    public ActionResult Login(string username,string userpass)
    {
      if (username==\"admin\" && userpass==\"admin\")
      {
        LoginUser loginuser = new LoginUser();
        loginuser.ID = 1;
        loginuser.UserName = username;
        loginuser.Roles = \"Administrator\";
        loginuser.Expires = DateTime.Now.AddHours(2);

        loginuser.Login(\"Administrator\");

        return Content(\"登录成功\");
        //return RedirectToAction(\"Index\", \"Home\");
      }

      return RedirectToAction(\"Login\");
    }

//是否登录
if(LoginUser.GetUserID(\"Administrator\") > 0)
{

}
// 用户ID
int userID=LoginUser.GetUserID(\"Administrator\")

//获取用户名
string userName= LoginUser.GetUser(\"Administrator\").UserName

  <form id=\"form1\" runat=\"server\">
  <script src=\"../Script/jquery-v1.10.2.js\" type=\"text/javascript\"></script>
  <script src=\"login.js\" type=\"text/javascript\"></script>
  <div class=\"\" style=\"height: 160px\">
    <div>
      <label for=\"userName\">
        帐号：</label>
      <input type=\"text\" name=\"userName\" />
    </div>
    <div>
      <label for=\"password\">
        密码：</label>
      <input type=\"password\" name=\"password\" />
    </div>
    <input type=\"submit\" id=\"btnSumit\" value=\"登录\" />
    <p class=\"msg\"> </p>
  </div>
  </form>

/*!
* 插件名称：登录插件封装，使用方法： 
   $(\'#form1\').login({
      url: \"LoginHandler.ashx\",//处理登录验证逻辑的Url
      userName: $(\"input[name=\'userName\']\"),//用户名输入框
      password: $(\"input[name=\'password\']\"),//密码输入框
      msg: $(\".msg\"),                    //提示信息
      button: $(\"#btnSumit\")              //提交按钮
    }); 
*/
(function ($) {
  $.fn.login = function (option) {
    var defaults = {
      url: \'/account/login/\',
      msg: $(this).find(\'.msg\'),
      userName: $(this).find(\"input[name=\'userName\']\"),
      password: $(this).find(\"input[name=\'password\']\"),
      button: $(this).find(\"#button\")
    };
    var options = $.extend(defaults, option);
    var errMsg = {
      \'inputUserName\': \'请输入用户名\',
      \'inputPassword\': \'请填写登录密码\',
      \'passwordLength\': \'密码应在6-32位字符内\',
      \'noreg\': \'此账号未注册\',
      \'inviladUserName\': \'帐号不存在\',
      \'accountNotMatch\': \'账号密码不匹配\',
      \'userLocked\': \'帐号锁定中，暂时无法登录\',
      \'serverdown\': \'服务器繁忙，请稍后再试\'
    };
    //提交数据
    function submit() {
      var userNameInput = $.trim(options.userName.val());
      var passwordInput = $.trim(options.password.val());
      if (userNameInput == \'\') {
        showMsg(\'登录名不能为空\');
        options.userName.focus();
        return;
      }
      if (passwordInput == \'\') {
        showMsg(\'密码不能为空\');
        options.password.focus();
        return;
      }
      $.ajax({
        type: \"POST\",
        url: options.url,
        data: \"userName=\" + userNameInput + \"&password=\" + passwordInput,
        success: function (msg) {
          var result = eval(\"[\" + msg + \"]\")[0];
          if (result.status == \"ok\") {
            //登录成功处理
            showMsg(\"登录成功....\");
          } else {
            showMsg(errMsg[result.status]);
          }
        }
      });
    }
    //显示错误信息
    function showMsg(msg) {
      options.msg.html(msg);
    }
    //绑定按钮事件
    options.button.bind(\'click\', function () {
      submit();
      return false;
    });
  };
})(jQuery);

  <script type=\"text/javascript\">
    $(\'#form1\').login({
      url: \"AjaxLogin.aspx\",
      userName: $(\"input[name=\'userName\']\"),
      password: $(\"input[name=\'password\']\"),
      msg: $(\".msg\"),
      button: $(\"#btnSumit\")
    });
  </script>

using System;
using System.Web;
using System.Web.UI;
namespace Whir.SiteFactory.Website.Admin.Account
{
  public partial class AjaxLogin : Page
  {
    protected void Page_Load(object sender, EventArgs e)
    {
      string status = ProcessLogin();
      Response.Clear();
      Response.Write(status);
      Response.End();
    }
    private string ProcessLogin()
    {
      try
      {
        string userName = HttpContext.Current.Request.Form[\"userName\"];
        string password = HttpContext.Current.Request.Form[\"password\"];
        if (string.IsNullOrEmpty(userName))
        {
          return \"{status:\'inputUserName\'}\"; //请输入用户名
        }
        if (string.IsNullOrEmpty(password))
        {
          return \"{status:\'inputPassword\'}\"; //请填写登录密码
        }
        if (password.Length < 6 || password.Length > 32)
        {
          return \"{status:\'passwordLength\'}\"; //密码应在6-32位字符内
        }
        //var user = UserService.GetUserByName(userName);
        //if (user == null)
        //{
        //  return \"{status:\'inviladUserName\'}\"; //帐号不存在
        //}
        //if (user.IsLocked)
        //{
        //  return \"{status:\'userLocked\'}\"; //帐号锁定中，暂时无法登录
        //}
        //if (user.Password.ToLower() != password.ToMd5().ToLower())
        //{ 
        //  return \"{accountNotMatch:\'ok\'}\"; //账号密码不匹配
        //}
        //其他操作：
        //写入客户端cookie
        //登录日志
        return \"{status:\'ok\'}\"; //登录成功
      }
      catch (Exception ex)
      {
        return \"{status:\'serverdown\'}\"; //服务器繁忙，请稍后再试
      }
    }
  }
}