Asp.net MVC中的ViewData与ViewBag

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

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

ViewDataViewBag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 frameworkViewData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。