[MVC]使用自定义ViewHelper来简化Asp.net MVC view的开发

<li>
<label for="FirstName">First name</label>
<%= Html.TextBox("FirstName") %>
<%= Html.ValidationMessage("FirstName", "*") %>
</li> 

<% Html.NewText("FirstName", "First name"); %> 

<%= Html.TextBox("FirstName") %> 

<% using (Html.BeginForm()) { %>
<!--  Other elements here-->
<% } %> 

public abstract class AbstractHtmlViewObject : IViewObject
{
private bool mDisposed;
public AbstractHtmlViewObject(ViewRequestContext requestContext, string name)
{
if (requestContext == null)
{ throw new ArgumentNullException("requestContext"); }
ViewRequestContext = requestContext;
Name = name;
}
public IViewRequestContext RequestContext
{
get;
protected set;
}
#region IViewObject Members
public object Attributes { get; set; }
public string Name { get; set; }
public abstract void StartView();
public abstract void EndView();
#endregion
// based on System.Web.Mvc.HtmlHelper.GetModelStateValue 
public object GetModelStateValue(string key, Type destinationType)
{
object result = null;
ModelState modelState;
if (ViewRequestContext.HtmlHelper.ViewData.ModelState.TryGetValue(
key, out modelState))
{
result = modelState.Value.ConvertTo(destinationType, null);
}
return result;
}
#region IDisposable Members
public void Dispose()
{
Dispose(true);
GC.SuppressFinalize(this);
}
protected virtual void Dispose(bool disposing)
{
if (!mDisposed)
{
mDisposed = true;
EndView();
}
}
#endregion
} 

private readonly string mLabelText;
private readonly bool mCreateLabel;
private readonly object mValue;
private readonly string mValidationMessage;
private readonly bool mCreateValidationMessage;
private readonly bool mCreateLi;
private readonly bool mReadonly;
public HtmlText(
ViewRequestContext requestContext, string name, string labelText, objec
string validationMessage, bool @readonly, bool createLi, object attribu
: base(requestContext, name)
{
mLabelText = labelText;
mCreateLabel = !string.IsNullOrEmpty(mLabelText);
mValidationMessage = validationMessage;
mCreateValidationMessage = !string.IsNullOrEmpty(validationMessage);
mCreateLi = createLi;
mReadonly = @readonly;
Attributes = attributes;
object valueToAssign = value;
if (valueToAssign == null)
{
// see if the ModelState has a value for this 
valueToAssign = GetModelStateValue(name, typeof(string));
}
mValue = valueToAssign;
} 

public static class HtmlHelperExtensions
{
#region Textbox
public static IViewObject NewText(
this HtmlHelper htmlHelper, string name)
{
return NewText(htmlHelper, name, null);
}
public static IViewObject NewText(
this HtmlHelper htmlHelper, string name, string labelText)
{
return NewText(htmlHelper, name, labelText, null);
}
public static IViewObject NewText(
this HtmlHelper htmlHelper, string name, string labelText, object value)
{
return NewText(htmlHelper, name, labelText, value, null, false, true, null);
}
public static IViewObject NewText(
this HtmlHelper htmlHelper, string name, string labelText, object value,
string validationMessage, bool @readonly, bool createLi, object attributes)
{
IViewObject viewObject = new HtmlText(
new ViewRequestContext(htmlHelper), name, labelText, value,
validationMessage, @readonly, createLi, attributes);
viewObject.StartView();
return viewObject;
}
#endregion
//NOTE: SOME CONTENT OMITTED FROM THIS SNIPPET 
} 

<li>
<label for="FirstName">First name</label>
<%= Html.TextBox("FirstName") %>
<%= Html.ValidationMessage("FirstName", "*") %>
</li> 

<% Html.NewText("FirstName", "First name"); %> 

<li>
<div class="option-group" id="GenderContainer">
<label for="Gender">Gender</label>
<% foreach (SelectListItem item in Model.GenderList)
{ %>
<%= Html.RadioButton(item.Text, item.Value)%>
<span><%= item.Text%></span>
<% } %>
</div>
</li> 

public ActionResult AddContactClassic()
{
AddContactModel addModel = InternalGetInitialAddModel();
return View(addModel);
}
private AddContactModel InternalGetInitialAddModel()
{
string maleString = Gender.Male.ToString();
string femaleString = Gender.Female.ToString();
IList<SelectListItem> genderRadioButtons = new List<SelectListItem>()
{
new SelectListItem { Text = maleString, Value = maleString },
new SelectListItem { Text = femaleString, Value = femaleString }
};
AddContactModel model = new AddContactModel { GenderList = genderRadioButtons };
return model;
} 

<% Html.NewRadioButtonGroup("Gender", Model.GenderList); %> 

private readonly List<SelectListItem> mSelectList;
private readonly bool mCreateLi;
public HtmlRadioButtonGroup(
ViewRequestContext requestContext, string name,
IEnumerable<SelectListItem> selectList, bool createLi, object attributes)
: base(requestContext, name)
{
mSelectList = new List<SelectListItem>();
if (selectList != null)
{
mSelectList.AddRange(selectList);
}
mCreateLi = createLi;
Attributes = attributes;
}

public override void StartView()
{
HttpResponseBase httpResponse = RequestContext.HttpResponse;
TagBuilder liTagBuilder = new TagBuilder("li");
if (mCreateLi)
{
httpResponse.Write(liTagBuilder.ToString(TagRenderMode.StartTag));
}
TagBuilder divTag = new TagBuilder("div");
divTag.AddCssClass("option-group");
divTag.MergeAttribute("name", Name);
if (Attributes != null)
{
divTag.MergeAttributes(new RouteValueDictionary(Attributes));
}
TagBuilder labelTag = new TagBuilder("label");
labelTag.MergeAttribute("for", Name);
labelTag.SetInnerText(Name);
httpResponse.Write(labelTag.ToString(TagRenderMode.Normal));
httpResponse.Write(divTag.ToString(TagRenderMode.StartTag));
// Write out the radio buttons, let the MVC Helper do the hard work here 
foreach (SelectListItem item in this.mSelectList)
{
string text = !string.IsNullOrEmpty(item.Text)
? item.Text
: item.Value;
httpResponse.Write(RequestContext.HtmlHelper.RadioButton(
Name, item.Value, item.Selected));
// Note: Because we are using HtmlHelper.RadioButton the <input>  
//       elements will have duplicate ids 
//       See: http://forums.asp.net/t/1363177.aspx 
//       In order to avoid this we could do this ourselves here 
TagBuilder spanTag = new TagBuilder("span");
spanTag.SetInnerText(text);
httpResponse.Write(spanTag.ToString(TagRenderMode.Normal));
}
httpResponse.Write(divTag.ToString(TagRenderMode.EndTag));
if (this.mCreateLi)
{
httpResponse.Write(liTagBuilder.ToString(TagRenderMode.EndTag));
}
} 

public static IViewObject NewHtmlFieldSet(
this HtmlHelper htmlhelper, string name, string title, object attributes)
{
IViewObject viewObject = new HtmlFieldSet(
new ViewRequestContext(htmlhelper), name, title, attributes);
viewObject.StartView();
return viewObject;
} 

<% using (Html.NewHtmlFieldset("FieldsetName", "My Fieldset", null))
{ %>
<li>
<label for="FirstName">FirstName</label>
<span id="FirstName"><%= Html.Encode(Model.FirstName) %></span>
</li>
<% } %> 

<fieldset name="FieldsetName">
<legend>My Fieldset</legend>
<ol>
<li>
<label for="FirstName">FirstName</label>
<span id="FirstName">Sayed</span>
</li>
</ol>
</fieldset> 

<%@ Page Title="" Language="C#" MasterPageFile="~/Views/Shared/Site.Master"
Inherits="System.Web.Mvc.ViewPage<Sedodream.Web.ViewHelper.Models.AddContactModel>"
%>
<%@ Import Namespace="Sedodream.Web.Common.Contact" %>
<asp:Content ID="Content1" ContentPlaceHolderID="TitleContent" runat="server">
Add Contact Classic
</asp:Content>
<asp:Content ID="Content2" ContentPlaceHolderID="MainContent" runat="server">
<h2>Add Contact Classic</h2>
<%= Html.ValidationSummary("Errors exist") %>
<ol>     <li>
<span class="success-message"><%= ViewData["SuccessMessage"]%></span>
</li>
</ol>
<% using (Html.BeginForm())
{ %>
<fieldset>
<legend>Account Information</legend>
<ol>
<li>
<label for="FirstName">First name</label>
<%= Html.TextBox("FirstName") %>
<%= Html.ValidationMessage("FirstName", "*") %>
</li>
<li>
<label for="LastName">Last name</label>
<%= Html.TextBox("LastName") %>
<%= Html.ValidationMessage("LastName", "*") %>
</li>
<li>
<label for="Email">Email</label>
<%= Html.TextBox("Email")%>
<%= Html.ValidationMessage("Email", "*")%>
</li>
<li>
<label for="Phone">Phone</label>
<%= Html.TextBox("Phone")%>
<%= Html.ValidationMessage("Phone", "*")%>
</li>
<li>
<div class="option-group" id="GenderContainer">
<label for="Gender">Gender</label>
<% foreach (SelectListItem item in Model.GenderList)
{ %>
<%= Html.RadioButton(item.Text, item.Value)%>
<span><%= item.Text%></span>
<% } %>
</div>
</li>
<li>
<input type="submit" value="Add contact" />
</li>
</ol>
</fieldset>
<% } %>
</asp:Content> 

<%@ Page
Inherits="System.Web.Mvc.ViewPage<Sedodream.Web.ViewHelper.Models.AddContactModel>"
Language="C#" MasterPageFile="~/Views/Shared/Site.Master" Title="" %>
<%@ Import Namespace="Sedodream.Web.Common.View" %>
<asp:Content ID="Content1" ContentPlaceHolderID="TitleContent" runat="server">
Add Contact New
</asp:Content>
<asp:Content ID="Content2" ContentPlaceHolderID="MainContent" runat="server">
<h2>Add Contact New</h2>
<%= Html.ValidationSummary("Errors exist") %>
<ol>
<li>
<span class="success-message"><%= Model.SuccessMessage %></span>
</li>
</ol>
<% using (Html.BeginForm())
{ %>
<fieldset>
<legend>Account Information</legend>
<ol>
<% Html.NewText("FirstName", "First name"); %>
<% Html.NewText("LastName", "Last name"); %>
<% Html.NewText("Email", "Email"); %>
<% Html.NewText("Phone", "Phone"); %>
<% Html.NewRadioButtonGroup("Gender", Model.GenderList); %>
<li>
<input type="submit" value="Add contact" />
</li>
</ol>
</fieldset>
<% } %>
</asp:Content> 

case InputType.Radio:
if (!usedModelState) {
string modelStateValue = htmlHelper.GetModelStateValue(
name, typeof(string)) as string;
if (modelStateValue != null) {
isChecked = String.Equals(
modelStateValue, valueParameter, StringComparison.Ordinal);
usedModelState = true;
}
}