public ActionResult Login(UserLoginViewModel uViewModel)
        {
            if (ModelState.IsValid)
            {
                var user = db.ADUsers.SingleOrDefault(t => t.usrName == uViewModel.usrName && t.usrPassword == uViewModel.usrPassword);

                if (user != null)
                {
                    FormsAuthentication.SetAuthCookie(uViewModel.usrName, false);//将用户名放入Cookie中
                    System.Web.HttpContext.Current.Session["usrName"] = uViewModel.usrName; //将用户名放入session中

                    return RedirectToAction("Index","Home");
                }
                else
                {
                    ModelState.AddModelError("usrName", "用户名不存在!");
                }
            }
            return View(uViewModel);
        }

@if (Session["usrName"] != null)
{
    using (Html.BeginForm("LogOff", "ADUsers", FormMethod.Post, new { id = "logoutForm", @class = "navbar-right" }))
    {
        @Html.AntiForgeryToken()

        <ul class="nav navbar-nav navbar-right">
            <li>
                @Html.ActionLink("你好，" + Session["usrName"] + "!", "Index", "Manage", routeValues: null, htmlAttributes: new { title = "Manage" })
            </li>
            <li><a href=http://www.mamicode.com/"javascript:document.getElementById(‘logoutForm‘).submit()">注销</a></li>
        </ul>
    }
}
else
{
    <ul class="nav navbar-nav navbar-right">
        <li>@Html.ActionLink("登录", "Login", "ADUsers", routeValues: null, htmlAttributes: new { id = "loginLink" })</li>
        <li>cookies:@Session["usrName"];</li>
    </ul>

        public ActionResult LogOff()
        {
            FormsAuthentication.SignOut();
            System.Web.HttpContext.Current.Session["usrName"] = null;
            return RedirectToAction("Login");
        }