Razor 语法初级使用，不断更新此文章

有兴趣的可以看看菜鸟教程的   http://www.runoob.com/aspnet/razor-cs-loops.html

1.ViewData展示登陆的Session信息

Controller:

  public ActionResult Index()
         {
             if (Session["username"] == null)
             {
                 Response.Redirect("/Login/Index");
             }
             else
             {
                 ViewData["username"] = Session["username"].ToString();
             }
             return View();
         }

View:

  <a href="#" class="dropdown-toggle" data-toggle="dropdown" role="button"
                            aria-expanded="false">
                             <i class="fa fa-user-o fa-fw"></i>
                             @if (ViewData["username"]!=null)
                             {
                                     @ViewData["username"].ToString();
                             }
                             <span class="caret"></span>
                         </a>

效果：