Asp.net MVC中的ViewData与ViewBag（转）

在Asp.net MVC 3 web应用程序中，我们会用到ViewData与ViewBag，对比一下： 

ViewData	ViewBag
它是Key/Value字典集合	它是dynamic类型对像
从Asp.net MVC 1 就有了	ASP.NET MVC3 才有
基于Asp.net 3.5 framework	基于Asp.net 4.0与.net framework
ViewData比ViewBag快	ViewBag比ViewData慢
在ViewPage中查询数据时需要转换合适的类型	在ViewPage中查询数据时不需要类型转换
有一些类型转换代码	可读性更好

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> 

后面是在Controller中使用ViewBag:

public ActionResult UsingViewBagInControlAndViewDataInView() {      ViewBag.Title = " Using ViewBag In Control And ViewData In View";     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(); }

在UsingViewBagInControlAndViewDataInView.cshtml中使用ViewData来取值：

<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> 

反过来是这样的: 

public ActionResult UsingViewDataInControlAndViewBagInView() {     ViewData["Title"] = " Using ViewData In Control And ViewBag In View";     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(); }

在UsingViewDataInControlAndViewBagInView.cshtml 的View中使用ViewBag来取值:

<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> 

这样对比看上去会比较清楚一些。在源代码中的ViewBag是这样的属性:

public dynamic ViewBag {     get {         if (_dynamicViewData == null) {             _dynamicViewData = new DynamicViewDataDictionary(() => ViewData);         }         return _dynamicViewData;     } }

ViewData是：

public ViewDataDictionary ViewData {     get {         if (_viewData == null) {             SetViewData(new ViewDataDictionary());         }         return _viewData;     }     set {         SetViewData(value);     } }

具体细节在这儿不深入了，这里只是抛砖引玉。希望对您Asp.net MVC开发有帮助。

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