（转）MVC Controller与ActionResult的返回值

本是古典何须时尚 2021-12-22 07:45 218阅读 0赞

原文：[http://www.cnblogs.com/xumingming/archive/2009/09/22/1571510.html][http_www.cnblogs.com_xumingming_archive_2009_09_22_1571510.html]

Action的要求  
• 必须是一个公有方法  
• 必须返回ActionResult类型  
• 必须是实例方法  
• 不能是范型方法  
• 没有标注NonActionAttribute  
• 不能被重载（overload）

Controller 提供了众多的方法让我们返回各种类型的 ActionResult。

![2009092208012633.png][]

**1. View**  
  
最常用的一种，用于返回一个 "标准" 页面。

protected internal virtual ViewResult View(string viewName, string masterName, object model)  
\{  
if (model != null)  
\{  
base.ViewData.Model = model;  
\}  
  
return new ViewResult  
\{  
ViewName = viewName,  
MasterName = masterName,  
ViewData = base.ViewData,  
TempData = base.TempData  
\};  
\}  
  
public class ViewResult : ViewResultBase  
\{  
protected override ViewEngineResult FindView(ControllerContext context)  
\{  
ViewEngineResult result = ViewEngineCollection.FindView(context, ViewName, MasterName);  
  
if (result.View != null)  
\{  
return result;  
\}  
  
...  
\}  
\}

这个页面默认是 ViewPage，也可以是我们自己定义的其它模板引擎页面。  
  
MVC 还提供了强类型的 ViewPage<TModel>。

public class User  
\{  
public string Name \{ get; set; \}  
public int Age \{ get; set; \}  
\}  
  
public class TestController : Controller  
\{  
public ActionResult Index()  
\{  
ViewData\["message"\] = "Hello, World!";  
var model = new User \{ Name = "Tom", Age = 13 \};  
  
return View(model);  
\}  
\}

Index.aspx

<%@ Page Language="C\#" Inherits="System.Web.Mvc.ViewPage<Learn.MVC.Controllers.User>" %>  
  
<html xmlns="http://www.w3.org/1999/xhtml">  
<head runat="server">  
<title>Index</title>  
</head>  
<body>  
Name: <%= Model.Name %>; Age: <%= Model.Age %>  
</body>  
</html>

在 WebForm 时代，我们就已经习惯了将一个页面分解成多个 UserControl，现在我们依然可以这么做。htmlHelper 专门提供了 RenderPartial 扩展方法，从当前视图目录(Views\\xxx)下载入 .ascx 页面。

public static class RenderPartialExtensions  
\{  
public static void RenderPartial(this HtmlHelper htmlHelper, partialViewName, model, viewData)  
\{  
htmlHelper.RenderPartialInternal(partialViewName, viewData, model, ViewEngines.Engines);  
\}  
\}  
  
public class HtmlHelper  
\{  
internal virtual void RenderPartialInternal(string partialViewName, ViewDataDictionary viewData,  
object model, ViewEngineCollection viewEngineCollection)  
\{  
...  
  
ViewDataDictionary newViewData = null;  
  
if (model == null)  
\{  
if (viewData == null)  
newViewData = new ViewDataDictionary(ViewData);  
else  
newViewData = new ViewDataDictionary(viewData);  
\}  
else  
\{  
if (viewData == null)  
newViewData = new ViewDataDictionary(model);  
else  
newViewData = new ViewDataDictionary(viewData) \{ Model = model \};  
\}  
  
ViewContext newViewContext = new ViewContext(ViewContext, ViewContext.View,  
newViewData, ViewContext.TempData);  
  
IView view = FindPartialView(newViewContext, partialViewName, viewEngineCollection);  
  
view.Render(newViewContext, ViewContext.HttpContext.Response.Output);  
\}  
  
internal static IView FindPartialView(viewContext, partialViewName, viewEngineCollection)  
\{  
ViewEngineResult result = viewEngineCollection.FindPartialView(viewContext, partialViewName);  
  
if (result.View != null)  
\{  
return result.View;  
\}  
  
...  
\}  
\}

RenderPartialInternal 调用 FindParitialView 从视图引擎中载入 .ascx，同时将当前的环境参数传递给它。也就是说 RenderPartial 只是一种视图级别的行为，并不会再次触发 Controller Action 操作，这点要和 Controller.PartialView() 区别开来。  
  
Index.aspx

Part.ascx

<%@ Control Language="C\#" Inherits="System.Web.Mvc.ViewUserControl<Learn.MVC.Controllers.User>" %>  
  
<%= ViewData\["message"\] %>  
<br />  
<%= Model.Name %>

**2. Content**  
  
Content 用于输出(Response.Write) "静态" 片段。

protected internal virtual ContentResult Content(content, contentType, contentEncoding)  
\{  
return new ContentResult  
\{  
Content = content,  
ContentType = contentType,  
ContentEncoding = contentEncoding  
\};  
\}  
  
public class ContentResult : ActionResult  
\{  
public string Content \{ get; set; \}  
  
public override void ExecuteResult(ControllerContext context)  
\{  
...  
  
HttpResponseBase response = context.HttpContext.Response;  
  
if (!String.IsNullOrEmpty(ContentType))  
\{  
response.ContentType = ContentType;  
\}  
if (ContentEncoding != null)  
\{  
response.ContentEncoding = ContentEncoding;  
\}  
if (Content != null)  
\{  
response.Write(Content);  
\}  
\}  
\}

看看和 jQuery 的配合使用。

public class TestController : Controller  
\{  
public ActionResult Index()  
\{  
return View();  
\}  
  
public ActionResult Part()  
\{  
return Content("<a href=\\"http://www.rainsts.net\\">Q.yuhen</a>");  
\}  
\}

Index.aspx

<%@ Page Language="C\#" Inherits="System.Web.Mvc.ViewPage" %>  
  
<html xmlns="http://www.w3.org/1999/xhtml">  
<head runat="server">  
<title>Index</title>  
<script src="http://www.cnblogs.com/Scripts/jquery-1.3.1.min.js" type="text/javascript"></script>  
<script type="text/javascript">  
$(function()  
\{  
$("\#div1").load("/test/part");  
\});  
</script>  
</head>  
<body>  
<div id="div1">  
</div>  
</body>  
</html>

**3. PartialView**  
  
Controller.PartialView() 和 HtmlHelper.RenderPartial() 的不同之处在于前者是再次执行 ActionInvoke 并返回一个 ActionResult 结果，后者只是使用现有的 ViewContext 显示一个视图片段。而与 Controller.Content() 的区别是 PartialView() 使用视图引擎输出一个 "动态" 的 ascx 结果。

protected internal virtual PartialViewResult PartialView(string viewName, object model)  
\{  
if (model != null)  
\{  
ViewData.Model = model;  
\}  
  
return new PartialViewResult  
\{  
ViewName = viewName,  
ViewData = ViewData,  
TempData = TempData  
\};  
\}  
  
public class PartialViewResult : ViewResultBase  
\{  
protected override ViewEngineResult FindView(ControllerContext context)  
\{  
ViewEngineResult result = ViewEngineCollection.FindPartialView(context, ViewName);  
  
if (result.View != null)  
\{  
return result;  
\}  
  
...  
\}  
\}

和 Content() 一样，我们通常将其和 jQuery 等 Ajax 框架配合使用。

public class TestController : Controller  
\{  
public ActionResult Index()  
\{  
return View();  
\}  
  
public ActionResult Part()  
\{  
ViewData\["time"\] = DateTime.Now;  
var model = new User \{ Name = "Tom", Age = 13 \};  
  
return PartialView(model);  
\}  
\}

Index.aspx

Part.ascx

<%@ Control Language="C\#" Inherits="System.Web.Mvc.ViewUserControl<Learn.MVC.Controllers.User>" %>  
  
<%= ViewData\["time"\] %> <br />  
<%= Model.Name %>; <%= Model.Age %>

**4. Redirect / RedirectToAction / RedirectToRoute**  
  
Controller 提供了几种方式，让我们在不同的 Action 之间进行跳转。

public class MvcApplication : System.Web.HttpApplication  
\{  
public static void RegisterRoutes(RouteCollection routes)  
\{  
...  
  
routes.MapRoute  
(  
"Test2",  
"Test/T2/\{name\}/\{age\}",  
new \{ controller = "Test", action = "T2", name = "", age = 0 \}  
);  
  
...  
\}  
\}

**方法1**:  
  
Redirect() 直接用 Response.Redirect() 完成 url 跳转。

public class TestController : Controller  
\{  
public ActionResult Index()  
\{  
return Redirect("/Test/T2/Tom/23");  
\}  
  
public ActionResult T2(User user)  
\{  
return Content(user.Name);  
\}  
\}

相关细节：

protected internal virtual RedirectToRouteResult RedirectToRoute(string routeName, RouteValueDictionary routeValues)  
\{  
return new RedirectToRouteResult(routeName, RouteValuesHelpers.GetRouteValues(routeValues));  
\}

执行过程和 RedirectToAction() 相同。  
  
**5. Json**  
  
Json() 在编写 Ajax 时非常有用，可以将 Entity 等对象序列化成 JSON 格式供 Javascript 使用。

public class TestController : Controller  
\{  
public ActionResult Index()  
\{  
return View();  
\}  
  
public ActionResult GetUser(string name)  
\{  
var user = new User \{ Name = name, Age = 23 \};  
return Json(user);  
\}  
\}

Index.aspx

<%@ Page Language="C\#" Inherits="System.Web.Mvc.ViewPage" %>  
  
<html xmlns="http://www.w3.org/1999/xhtml">  
<head runat="server">  
<title>Index</title>  
<script src="http://www.cnblogs.com/Scripts/jquery-1.3.1.min.js" type="text/javascript"></script>  
<script type="text/javascript">  
$(function()  
\{  
$("\#btnTest").click(function()  
\{  
$.getJSON  
(  
"/Test/GetUser",  
\{ name: "Tom" \},  
function(json)  
\{  
alert(json.Name + ";" + json.Age);  
\}  
);  
\});  
\});  
</script>  
</head>  
<body>  
<input type="button" id="btnTest" value="Test" />  
</body>  
</html>

很好用，不是吗？看看相关细节。

protected internal virtual JsonResult Json(object data, string contentType, Encoding contentEncoding)  
\{  
return new JsonResult  
\{  
Data = data,  
ContentType = contentType,  
ContentEncoding = contentEncoding  
\};  
\}  
  
public class JsonResult : ActionResult  
\{  
public override void ExecuteResult(ControllerContext context)  
\{  
...  
  
if (Data != null)  
\{  
JavaScriptSerializer serializer = new JavaScriptSerializer();  
response.Write(serializer.Serialize(Data));  
\}  
\}  
\}

使用 System.Web.Script.Serialization.JavaScriptSerializer 完成 JSON 序列化操作，也就是说我们还可以用 ScriptIgnoreAttribute 排除某些属性。  
  
**6. Javascript**  
  
某些时候，我们需要根据一些逻辑判断来载入执行不同的 Javascript 代码。

public class TestController : Controller  
\{  
public ActionResult Index()  
\{  
return View();  
\}  
  
public ActionResult GetJs(int id)  
\{  
switch (id)  
\{  
case 1:  
return JavaScript("alert('Hello, C\#!');");  
case 2:  
return JavaScript("alert('Hello, MVC!');");  
default:  
return null;  
\}  
\}  
\}

Index.aspx

<%@ Page Language="C\#" Inherits="System.Web.Mvc.ViewPage" %>  
  
<html xmlns="http://www.w3.org/1999/xhtml">  
<head runat="server">  
<title>Index</title>  
<script src="http://www.cnblogs.com/Scripts/jquery-1.3.1.min.js" type="text/javascript"></script>  
<script type="text/javascript">  
$(function()  
\{  
$("\#btnTest").click(function()  
\{  
var id = $("\#txtId").val();  
$.getScript("/Test/GetJs/" + id);  
\});  
\});  
</script>  
</head>  
<body>  
<input type="text" id="txtId" value="1" />  
<input type="button" id="btnTest" value="Test" />  
</body>  
</html>

只是这种做法，似乎将 View 和 Controller 的耦合加大了…… 还不如直接用 Javascript 来处理这些。

protected internal virtual JavaScriptResult JavaScript(string script)  
\{  
return new JavaScriptResult \{ Script = script \};  
\}  
  
public class JavaScriptResult : ActionResult  
\{  
public override void ExecuteResult(ControllerContext context)  
\{  
...  
  
HttpResponseBase response = context.HttpContext.Response;  
response.ContentType = "application/x-javascript";  
  
if (Script != null)  
\{  
response.Write(Script);  
\}  
\}  
\}

**7. File (Download / Upload)**  
  
File() 提供了 Download 功能。

public class TestController : Controller  
\{  
public ActionResult Index()  
\{  
return View();  
\}  
  
public ActionResult Download(int id)  
\{  
var filename = String.Format("~/Content/Download/\{0\}.rar", id);  
var fileDownloadName = String.Format("\{0\}.rar", id);  
  
return File(filename, "application/octet-stream", fileDownloadName);  
\}  
\}

当我们在浏览器请求 "/Test/Download/1" 是就会打开下载窗口，同时给出了保存文件名。

protected internal virtual FileContentResult File(byte\[\] fileContents, contentType, fileDownloadName)  
\{  
return new FileContentResult(fileContents, contentType) \{ FileDownloadName = fileDownloadName \};  
\}  
  
public abstract class FileResult : ActionResult  
\{  
public override void ExecuteResult(ControllerContext context)  
\{  
...  
HttpResponseBase response = context.HttpContext.Response;  
response.ContentType = ContentType;  
...  
WriteFile(response);  
\}  
  
protected abstract void WriteFile(HttpResponseBase response);  
\}  
  
public class FileContentResult : FileResult  
\{  
protected override void WriteFile(HttpResponseBase response)  
\{  
response.OutputStream.Write(FileContents, 0, FileContents.Length);  
\}  
\}

文件上传是另一个常用的 Web 应用。

public class TestController : Controller  
\{  
public ActionResult Index()  
\{  
return View();  
\}  
  
public ActionResult Upload(HttpPostedFileBase file)  
\{  
var filename = Server.MapPath("~/Content/Upload/" + Path.GetFileName(file.FileName));  
  
file.SaveAs(filename);  
return null;  
\}  
\}

Index.aspx

<%@ Page Language="C\#" Inherits="System.Web.Mvc.ViewPage" %>  
  
<html xmlns="http://www.w3.org/1999/xhtml">  
<head runat="server">  
<title>Index</title>  
</head>  
<body>  
<form action="/Test/Upload" enctype="multipart/form-data" method="post">  
<input type="file" name="file" />  
<input type="submit" name="upload" />  
</form>  
</body>  
</html>

MVC 提供了一个 HttpPostedFileBaseModelBinder 将 Request.Files 的信息直接映射给 Action 同名参数。

public class HttpPostedFileBaseModelBinder : IModelBinder  
\{  
public object BindModel(ControllerContext controllerContext, ModelBindingContext bindingContext)  
\{  
...  
  
HttpPostedFileBase theFile = controllerContext.HttpContext.Request.Files\[bindingContext.ModelName\];  
  
// case 1: there was no <input type="file" ... /> element in the post  
if (theFile == null)  
\{  
return null;  
\}  
  
// case 2: there was an <input type="file" ... /> element in the post, but it was left blank  
if (theFile.ContentLength == 0 && String.IsNullOrEmpty(theFile.FileName))  
\{  
return null;  
\}  
  
// case 3: the file was posted  
return theFile;  
\}  
\}

看看一次上传多个文件的演示。

public class TestController : Controller  
\{  
public ActionResult Index()  
\{  
return View();  
\}  
  
public ActionResult Upload(HttpPostedFileBase file1, HttpPostedFileBase file2)  
\{  
var html = String.Format("\{0\}:\{1\}<br />\{2\}:\{3\}",  
file1.FileName, file1.InputStream.Length,  
file2.FileName, file2.InputStream.Length);  
  
return Content(html);  
\}  
\}

Index.aspx

<%@ Page Language="C\#" Inherits="System.Web.Mvc.ViewPage" %>  
  
<html xmlns="http://www.w3.org/1999/xhtml">  
<head runat="server">  
<title>Index</title>  
</head>  
<body>  
<form action="/Test/Upload" enctype="multipart/form-data" method="post">  
<input type="file" name="file1" />  
<input type="file" name="file2" />  
<input type="submit" name="upload" />  
</form>  
</body>  
</html>

我们上边所看到的Action都是return View();我们可以看作这个返回值用于解析一个aspx文件。而它的返回类型是ActionResult如

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

除了View（）之外那我们这里还能用于返回什么值呢？

## 一、ascx页面 ##

场景：要返回代码片断，比如Ajax返回一个子页

我们先新建一个Action

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

我们下面再建一个View，仍然是在Action中点右键，AddView。

[![image][]][image 1] 注意图中勾选。

于是新建了一个ascx页，我们将之少做改写一下

<%@ Control Language="C#" Inherits="System.Web.Mvc.ViewUserControl" %>
    
    <div>
    得到一个DIV
    </div>

运行，得到页面

[![image][image 2]][image_image 2]

## 二、返回文本 ##

除了上述情况，有时我们还会仅返回一段文本。

此时我们可以使用以下Action形式：

public ActionResult Text(){
                return Content("这是一段文本");
            }

## 三、返回Json ##

有时我们在调用Ajax时还会要求返回对象为Json序列化的结果，如：

public ActionResult ShowJson()
            {
                var m = new EiceIndexModel
                {
                    Name = "邹健",
                    Sex = true
                };
                return Json(m);
            }

返回文本：

{"Name":"邹健","Sex":true}

## 四、输出JS文件 ##

大多时候js文件都是静态的，但有时js文件可能也要动态生成这时我们可以这样输出

public ActionResult Js()
            {
                return JavaScript("var x=0;");
            }

我们访问之，得到一个正常页面但其Content-Type：application/x-javascript; charset=utf-8

## 五、页面跳转 ##

1.跳转到Url

public ActionResult rdurl()
            {
                return Redirect("http://www.baidu.com");
            }

2.跳转到Action

public ActionResult rdaction()
            {
                return RedirectToAction("Index","Eice");
            }

3.跳转到Routing规则

public ActionResult rdrouting()
            {
                return RedirectToRoute("Default",//Route名
                  new{
                      Controller = "Eice",
                      Action = "Index"
                  });
            }

## 六、显示文件 ##

public ActionResult fn()
            {
                return File(
                    "/Content/site.css"//文件路径
                    , "text/css"//文件类型
                    );
            }

转载于:https://www.cnblogs.com/sofire/articles/1603982.html

[http_www.cnblogs.com_xumingming_archive_2009_09_22_1571510.html]: http://www.cnblogs.com/xumingming/archive/2009/09/22/1571510.html
[2009092208012633.png]: /images/20211220/0c4037cc26584c62baca3afa47d73898.png
[image]: /images/20211220/df7ca1eb9faa4a6d97fc33698e37ebd1.png
[image 1]: http://images.cnblogs.com/cnblogs_com/chsword/WindowsLiveWriter/ASP.NETMVCActionResult_52D/image_2.png
[image 2]: https://images.cnblogs.com/cnblogs_com/chsword/WindowsLiveWriter/ASP.NETMVCActionResult_52D/image_thumb_1.png
[image_image 2]: /images/20211220/57f1fa32c9714812ab206812d9b61a22.png