今天公司要写学习总结，想着想着还是先写一篇关于MVC内部什么东东的博客整理整理再发表吧，一举两得。
之前写过了路由、过滤器等。今天就研究一下怎么自定义MVC控件吧。
本人技术小菜，不喜勿喷。。。。。（说这句话通常有两种情况，一种是牛人谦虚的说法，一种是怕受伤害提前准备个挡箭牌）
首先我们先去熟知一下MVC内部的那些控件是怎么实现的。
首先,Input标签是大佬，我给各位看管来上一小段Password的吧。
public static class InputExtensions {
public static MvcHtmlString Password(this HtmlHelper htmlHelper, string name) {
return Password(htmlHelper, name, null /* value */);
} public static MvcHtmlString Password(this HtmlHelper htmlHelper, string name, object value) {
return Password(htmlHelper, name, value, null /* htmlAttributes */);
} public static MvcHtmlString Password(this HtmlHelper htmlHelper, string name, object value, object htmlAttributes) {
return Password(htmlHelper, name, value, HtmlHelper.AnonymousObjectToHtmlAttributes(htmlAttributes));
} public static MvcHtmlString Password(this HtmlHelper htmlHelper, string name, object value, IDictionary<string, object> htmlAttributes) {
return PasswordHelper(htmlHelper, null /* metadata */, name, value, htmlAttributes);
} [SuppressMessage("Microsoft.Design", "CA1006:DoNotNestGenericTypesInMemberSignatures", Justification = "This is an appropriate nesting of generic types")]
public static MvcHtmlString PasswordFor<TModel, TProperty>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TProperty>> expression) {
return PasswordFor(htmlHelper, expression, null /* htmlAttributes */);
}
}
InputExtensions
这定义的都是扩展方法，实现了重载，我们看到最后一个方法调用的是PasswordHelper 方法
private static MvcHtmlString PasswordHelper(HtmlHelper htmlHelper, ModelMetadata metadata, string name, object value, IDictionary<string, object> htmlAttributes) {
return InputHelper(htmlHelper, InputType.Password, metadata, name, value, false /* useViewData */, false /* isChecked */, true /* setId */, true /* isExplicitValue */, htmlAttributes);
}
但其最终调用的还是InputHelper方法，我们可以展开看看…..
private static MvcHtmlString InputHelper(HtmlHelper htmlHelper, InputType inputType, ModelMetadata metadata, string name, object value, bool useViewData, bool isChecked, bool setId, bool isExplicitValue, IDictionary<string, object> htmlAttributes) {
string fullName = htmlHelper.ViewContext.ViewData.TemplateInfo.GetFullHtmlFieldName(name);
if (String.IsNullOrEmpty(fullName)) {
throw new ArgumentException(MvcResources.Common_NullOrEmpty, "name");
} TagBuilder tagBuilder = new TagBuilder("input");
tagBuilder.MergeAttributes(htmlAttributes);
tagBuilder.MergeAttribute("type", HtmlHelper.GetInputTypeString(inputType));
tagBuilder.MergeAttribute("name", fullName, true); string valueParameter = Convert.ToString(value, CultureInfo.CurrentCulture);
bool usedModelState = false; switch (inputType) {
case InputType.CheckBox:
bool? modelStateWasChecked = htmlHelper.GetModelStateValue(fullName, typeof(bool)) as bool?;
if (modelStateWasChecked.HasValue) {
isChecked = modelStateWasChecked.Value;
usedModelState = true;
}
goto case InputType.Radio;
case InputType.Radio:
if (!usedModelState) {
string modelStateValue = htmlHelper.GetModelStateValue(fullName, typeof(string)) as string;
if (modelStateValue != null) {
isChecked = String.Equals(modelStateValue, valueParameter, StringComparison.Ordinal);
usedModelState = true;
}
}
if (!usedModelState && useViewData) {
isChecked = htmlHelper.EvalBoolean(fullName);
}
if (isChecked) {
tagBuilder.MergeAttribute("checked", "checked");
}
tagBuilder.MergeAttribute("value", valueParameter, isExplicitValue);
break;
case InputType.Password:
if (value != null) {
tagBuilder.MergeAttribute("value", valueParameter, isExplicitValue);
}
break;
default:
string attemptedValue = (string)htmlHelper.GetModelStateValue(fullName, typeof(string));
tagBuilder.MergeAttribute("value", attemptedValue ?? ((useViewData) ? htmlHelper.EvalString(fullName) : valueParameter), isExplicitValue);
break;
} if (setId) {
tagBuilder.GenerateId(fullName);
} // If there are any errors for a named field, we add the css attribute.
ModelState modelState;
if (htmlHelper.ViewData.ModelState.TryGetValue(fullName, out modelState)) {
if (modelState.Errors.Count > ) {
tagBuilder.AddCssClass(HtmlHelper.ValidationInputCssClassName);
}
} tagBuilder.MergeAttributes(htmlHelper.GetUnobtrusiveValidationAttributes(name, metadata)); if (inputType == InputType.CheckBox) {
// Render an additional <input type="hidden".../> for checkboxes. This
// addresses scenarios where unchecked checkboxes are not sent in the request.
// Sending a hidden input makes it possible to know that the checkbox was present
// on the page when the request was submitted.
StringBuilder inputItemBuilder = new StringBuilder();
inputItemBuilder.Append(tagBuilder.ToString(TagRenderMode.SelfClosing)); TagBuilder hiddenInput = new TagBuilder("input");
hiddenInput.MergeAttribute("type", HtmlHelper.GetInputTypeString(InputType.Hidden));
hiddenInput.MergeAttribute("name", fullName);
hiddenInput.MergeAttribute("value", "false");
inputItemBuilder.Append(hiddenInput.ToString(TagRenderMode.SelfClosing));
return MvcHtmlString.Create(inputItemBuilder.ToString());
} return tagBuilder.ToMvcHtmlString(TagRenderMode.SelfClosing);
}
InputHelper
该方法主要通过传递来的Input类型，还有一些name，value以及一些判断的界定来生产一个Input标签，最后返回一个MvcHtmlString对象。
其中实现我们就不做一一分析了，只是看看大概是如何实现的。
接下来我们自己定义一个简单的Input标签，类型为submit即提交的按钮。
namespace System.Web.Mvc.Html
{
public static class SubmitExtention
{
public const string DefaultSubmitValue = "提交"; public static MvcHtmlString Submit(this HtmlHelper htmlHelper)
{
return Submit(htmlHelper);
} public static MvcHtmlString Submit(this HtmlHelper htmlHelper, string value)
{
return Submit(htmlHelper, null, value);
} public static MvcHtmlString Submit(this HtmlHelper htmlHelper, string name, string value)
{
return Submit(htmlHelper, name, value, null);
} public static MvcHtmlString Submit(this HtmlHelper htmlHelper, string name, string value, IDictionary<string, string> attributes)
{
TagBuilder tag = new TagBuilder("input");
tag.Attributes.Add("type", "submit"); if (!string.IsNullOrEmpty(name))
{
tag.Attributes.Add("name", name);
} if (!string.IsNullOrEmpty(value))
{
tag.Attributes.Add("value", value);
}
else
{
tag.Attributes.Add("value", DefaultSubmitValue);
} if (null != attributes)
{
foreach (var attr in attributes)
{
tag.Attributes.Add(attr.Key, attr.Value);
}
}
return MvcHtmlString.Create(tag.ToString());
}
}
}
好了，我们去视图里看看吧。
点出来了吧，小伙伴们惊喜吗？
呵呵，其实一点都不惊喜，不久一个扩展方法吗？
不积跬步无以至千里，慢慢来，以后的路还很长，写博客只是为了总结，忘了的时候翻出来看看，温习温习，权当做笔记咯。
注意：
在视图配置文件中没有添加引用的情况下，小伙伴们可能点不出。
如果不行，你们还是把命名空间改为System.Web.Mvc.Html，像我这样，不然是点不出来的。
