ActionResult的返回类型

　　ActionResult是控制器方法执行后返回的结果类型，控制器方法可以返回一个直接或间接从ActionResult抽象类继承的类型，如果返回的是非ActionResult类型，控制器将会将结果转换为一个ContentResult类型。默认的ControllerActionInvoker调用ActionResult.ExecuteResult方法生成应答结果。

ActionResult是一个抽象类, 在Action中返回的都是其派生类，具体如下：

　　示例代码：

 public class ActionResultController : Controller
    {

        public ActionResult Index()
        {
            return View();
        }

        public ActionResult ContentResult()
        {
            return Content("Hi, 我是ContentResult结果");
        }

        public ActionResult EmptyResult()
        {
            return new EmptyResult();
        }

        public ActionResult FileResult()
        {
            var imgPath = Server.MapPath("~/demo.jpg");
            return File(imgPath, "application/x-jpg", "demo.jpg");
        }

        public ActionResult HttpNotFoundResult()
        {
            return HttpNotFound("Page Not Found");
        }

        public ActionResult HttpUnauthorizedResult()
        {
            //未验证时,跳转到Logon
            return new HttpUnauthorizedResult();
        }

        public ActionResult JavaScriptResult()
        {
            string js = "alert(\"Hi, I‘m JavaScript.\");";
            return JavaScript(js);
        }

        public ActionResult JsonResult()
        {
            var jsonObj = new
            {
                Id = 1,
                Name = "小铭",
                Sex = "男",
                Like = "足球"
            };

            return Json(jsonObj, JsonRequestBehavior.AllowGet);
        }

        public ActionResult RedirectResult()
        {
            return Redirect("~/demo.jpg");
        }

        public ActionResult RedirectToRouteResult()
        {
            return RedirectToRoute(new
            {
                controller = "Hello",
                action = ""
            });
        }

        public ActionResult ViewResult()
        {
            return View();
        }

        public ActionResult PartialViewResult()
        {
            return PartialView();
        }

        //禁止直接访问的ChildAction
        [ChildActionOnly]
        public ActionResult ChildAction()
        {
            return PartialView();
        }

        //正确使用ChildAction
        public ActionResult UsingChildAction()
        {
            return View();
        }

    }