在MVC3开始，视图数据可以通过ViewBag属性访问，在MVC2中则是使用ViewData。MVC3中保留了ViewData的使用。ViewBag 是动态类型（dynamic），ViewData 是一个字典型的（Dictionary）。

ViewBag和ViewData的区别：
ViewBag 不再是字典的键值对结构，而是 dynamic 动态类型，它会在程序运行的时候动态解析。所以在视图中获取它的数据时候不需要进行类型转换

1、ViewData是字典类型，赋值方式用字典方式，通过key值读取对应的value， ViewData["myName"]

2、ViewBag是动态类型，使用时直接添加属性赋值即可 ViewBag.myName

3、ViewBag和ViewData只在当前Action中有效，等同于View

4、ViewData和ViewBag 中的值可以互相访问，因为ViewBag的实现中包含了ViewData

-------------------ViewBag简单应用------------------------------------------------

Contorller

View

---------------------复杂应用----------------------------------

在Controller中使用ViewData:

public ActionResult UsingViewData()

{

    ViewData["Title"] = " Using ViewData";

    ViewData["ProjectName"] = "My Test Project";

    ViewData["ProjectDescription"] = "This is Test Project to demo Viewdata and viewbag details";

    ViewData["StartDate"] = new DateTime(2011, 1, 1);

    ViewData["TotalPrice"] = 1000;

    ViewData["TotalDays"] = 100;

    Dictionary<string, string> stackholder = new Dictionary<string, string>();

    stackholder.Add("Client","Mr.  Client");

    stackholder.Add("Manager","Mr. Joy");

    stackholder.Add("Team Leader","Mr.Toy");

    stackholder.Add("Sr. developer", "Mr.dojoy");

    stackholder.Add("developer", "Mr. nodoy");

    ViewData["stackholder"] = stackholder;

    List<string> modules = new List<string>();

    modules.Add("Admin module");

    modules.Add("ShoppingCart module");

    modules.Add("CMS module");

    ViewData["modules"] = modules;

    return View();

}

对应UsingViewData View的cshtml:

<h1>@ViewData["Title"]</h1>

 <div>

   <div>

    <h2>Project Name : @ViewData["ProjectName"]</h2>

   </div>

   <div>

     ProjectDescription :

     <p>"@ViewData["ProjectDescription"]".</p>

   </div>

   <div>

      Stack Holder :

      <br />

      <ul id="stakholder">

      @foreach ( var stakerholder in ViewData["stackholder"] as Dictionary<string, string> )

      {

    <li>

        @stakerholder.Key &nbsp; : @stakerholder.Value

    </li>

      }

     </ul>

   </div>

   <div>

     Project Details:<br />

     <div>

       module List  :

       <ul id="modulelist">

      @foreach ( var module in ViewData["modules"] as List<string> )

      {

    <li>

        @module

    </li>

      }

     </ul>

     </div>

     Project StartDate : @ViewData["StartDate"]  <br />

     Project TotalPrice: @ViewData["TotalPrice"] <br />

     Project TotaDays  : @ViewData["TotalDays"]

   </div>

 </div>

然后是ViewBag:

public ActionResult UsingViewBag()

{

    ViewBag.Title = " Using ViewBag";

    ViewBag.ProjectName = "My Test Project";

    ViewBag.ProjectDescription = "This is Test Project to demo Viewdata and viewbag details";

    ViewBag.StartDate = new DateTime(2011, 1, 1);

    ViewBag.TotalPrice = 1000;

    ViewBag.TotalDays = 100;

    Dictionary<string, string> stackholder = new Dictionary<string, string>();

    stackholder.Add("Client", "Mr.  Client");

    stackholder.Add("Manager", "Mr. Joy");

    stackholder.Add("Team Leader", "Mr.Toy");

    stackholder.Add("Sr. developer", "Mr.dojoy");

    stackholder.Add("developer", "Mr. nodoy");

    ViewBag.stackholder = stackholder;

    List<string> modules = new List<string>();

    modules.Add("Admin module");

    modules.Add("ShoppingCart module");

    modules.Add("CMS module");

    ViewBag.modules = modules;

    return View();

}

对应View UsingViewBag 的cshtml的ViewBag:

<h1>@ViewBag.Title</h1>

 <div>

   <div>

    <h2>Project Name : @ViewBag.ProjectName</h2>

   </div>

   <div>

     ProjectDescription :

     <p>"@ViewBag.ProjectDescription.</p>

   </div>

   <div>

      Stack Holder :

      <br />

      <ul id="stakholder">

      @foreach ( var stakerholder in ViewBag.stackholder )

      {

    <li>

        @stakerholder.Key &nbsp; : @stakerholder.Value

    </li>

      }

     </ul>

   </div>

   <div>

     Project Details:<br />

     <div>

       module List  :

       <ul id="modulelist">

      @foreach ( var module in ViewBag.modules )

      {

    <li>

        @module

    </li>

      }

     </ul>

     </div>

     Project StartDate : @ViewBag.StartDate.ToString("dd-MMM-yyyy") <br />

     Project TotalPrice: @ViewBag.TotalPrice  ₹  <br />

     Project TotaDays  : @ViewBag.TotalDays

   </div>

 </div>

-------------------------------TempData----------------------------------------------------

同ViewData和ViewBag一样，TempData也可以用来向视图传递数据。只是ViewData和ViewBag的生命周期和View相同，只对当前View有用。而TempData则可以在不同的Action中进行传值，类似webform里的Seesion。如下：

public ActionResult Index()

{

ViewBag.hello = "hello,this is viewBag";

ViewData["hi"] = "hi,this is viewData";

TempData["abc"] = "this is tempdata";

return View();

}

然后在About视图里面调用：

<h2>关于</h2>

<p>

@ViewBag.hello

@ViewData["key"]

@TempData["abc"]

</p>

页面效果如下：

这里只获取到了TempData["abc"]的值,但是TempData的值在取了一次后则会自动删除，这时我再刷新页面，则TempData["abc"]为Null了。通过反编译查看代码，发现TempData数据在调用后则会自动删除。详情请看：http://www.cnblogs.com/tristanguo/archive/2009/04/06/1430062.html

----------------------------------转载来源---------------------------------------------

简单应用

https://blog.csdn.net/Fanbin168/article/details/44803437

详细说明

http://www.cnblogs.com/bianlan/archive/2013/01/11/2857105.html

复杂应用

https://www.cnblogs.com/wintersun/archive/2012/01/21/2328563.html