如何在ASP.NET MVC中为相同视图维护Get和Post方法之间的数据？

Question

目前我正在使用此示例代码

        public ActionResult SampleView()
        {
            TempData["datetime"] = "Tempdata:  " + DateTime.Now.ToString();

            ViewBag.datetime = "ViewBag:   " + DateTime.Now.ToString();

            ViewData["datetime"] = "ViewData:  " + DateTime.Now.ToString();

            return View();

        }

        [HttpPost]
        public ActionResult SampleView(int? x) // 'x' is dummy variable, no use
        {
            string datetime1 = TempData["datetime"].ToString();

            string datetime2 = ViewBag.datetime;

            string datetime3 = ViewData["datetime"].ToString();    

            return RedirectToAction("SampleView");
        }

但以上都没有保留GET和POST之间的值。任何解决方案？