MVC扩展HtmlHelper，加入RadioButtonList、CheckBoxList、DropdownList

代码：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Linq.Expressions;
using System.Web;
using System.Web.Mvc;
using System.Web.Routing;
using System.Web.UI;

namespace System.Web.Mvc.Html
{
    public static class HtmlExtension
    {
        /// <summary>
        /// 扩展 DropdownList 列表1
        /// </summary>
        /// <param name="helper">扩展源</param>
        /// <param name="name">元素名称</param>
        /// <param name="items">SelectListItem集合</param>
        /// <param name="attributes">html属性</param>
        /// <returns></returns>
        public static MvcHtmlString DropdownList(this HtmlHelper helper, string name, IEnumerable<SelectListItem> items, object attributes = null)
        {
            return helper.DropDownList(name, items, attributes);
        }
        /// <summary>
        /// 扩展 DropdownList 列表2
        /// </summary>
        /// <param name="helper">扩展源</param>
        /// <param name="name">元素名称</param>
        /// <param name="viewDataName">ViewData键名称</param>
        /// <param name="attributes">html属性</param>
        /// <returns></returns>
        public static MvcHtmlString DropdownList(this HtmlHelper helper, string name, string viewDataName, object attributes = null)
        {
            List<SelectListItem> list = helper.ViewData[viewDataName] as List<SelectListItem>;
            return helper.DropDownList(name, list, attributes);
        }
        /// <summary>
        /// 扩展 DropdownList 列表3
        /// </summary>
        /// <typeparam name="TModel">实体</typeparam>
        /// <typeparam name="TValue">属性</typeparam>
        /// <param name="helper"></param>
        /// <param name="expression">表达式</param>
        /// <param name="items">数据列表</param>
        /// <param name="column">每行显示个数</param>
        /// <param name="attributes">html属性</param>
        /// <returns></returns>
        public static MvcHtmlString DropdownListFor<TModel, TValue>(this HtmlHelper<TModel> helper, Expression<Func<TModel, TValue>> expression, IEnumerable<SelectListItem> items, object attributes = null)
        {
            return helper.DropDownListFor(expression, items, attributes);
        }

        /// <summary>
        /// 扩展 DropdownList 列表4
        /// </summary>
        /// <typeparam name="TModel">实体</typeparam>
        /// <typeparam name="TValue">属性</typeparam>
        /// <param name="helper"></param>
        /// <param name="expression">表达式</param>
        /// <param name="viewDataName">viewData数据列表名称</param>
        /// <param name="attributes">html属性</param>
        /// <returns></returns>
        public static MvcHtmlString DropdownListFor<TModel, TValue>(this HtmlHelper<TModel> helper, Expression<Func<TModel, TValue>> expression, string viewDataName, object attributes = null)
        {
            List<SelectListItem> list = helper.ViewData[viewDataName] as List<SelectListItem>;
            return helper.DropdownListFor(expression, list, attributes);
        }

        /// <summary>
        /// 扩展 radiobutton 列表1
        /// </summary>
        /// <typeparam name="TModel">实体</typeparam>
        /// <typeparam name="TValue">属性</typeparam>
        /// <param name="helper"></param>
        /// <param name="expression">表达式</param>
        /// <param name="items">数据列表</param>
        /// <param name="column">每行显示个数</param>
        /// <param name="attributes">html属性</param>
        /// <returns></returns>
        public static MvcHtmlString RadioButtonListFor<TModel, TValue>(this HtmlHelper<TModel> helper, Expression<Func<TModel, TValue>> expression, IEnumerable<SelectListItem> items, int column = 0, object attributes = null)
        {
            string raidobuttonStr = "";
            BuildListTag(out raidobuttonStr, "radio", items, expression, column, attributes);
            return MvcHtmlString.Create(raidobuttonStr);
        }

        /// <summary>
        /// 扩展 radiobutton 列表2
        /// </summary>
        /// <typeparam name="TModel">实体</typeparam>
        /// <typeparam name="TValue">属性</typeparam>
        /// <param name="helper"></param>
        /// <param name="expression">表达式</param>
        /// <param name="viewDataName">viewData数据列表名称</param>
        /// <param name="column">每行显示个数</param>
        /// <param name="attributes">属性</param>
        /// <returns></returns>
        public static MvcHtmlString RadioButtonListFor<TModel, TValue>(this HtmlHelper<TModel> helper, Expression<Func<TModel, TValue>> expression, string viewDataName, int column = 0, object attributes = null)
        {
            string raidobuttonStr = "";
            var items = helper.ViewData[viewDataName] as List<SelectListItem>;
            BuildListTag(out raidobuttonStr, "radio", items, expression, column, attributes);
            return MvcHtmlString.Create(raidobuttonStr);
        }


        /// <summary>
        /// 扩展 CheckBox 列表1
        /// </summary>
        /// <typeparam name="TModel">实体</typeparam>
        /// <typeparam name="TValue">属性</typeparam>
        /// <param name="helper"></param>
        /// <param name="expression">表达式</param>
        /// <param name="items">数据列表</param>
        /// <param name="column">每行显示个数</param>
        /// <param name="attributes">html属性</param>
        /// <returns></returns>
        public static MvcHtmlString CheckBoxListFor<TModel, TValue>(this HtmlHelper<TModel> helper, Expression<Func<TModel, TValue>> expression, IEnumerable<SelectListItem> items, int column = 0, object attributes = null)
        {
            string raidobuttonStr = "";
            BuildListTag(out raidobuttonStr, "checkbox", items, expression, column, attributes);
            return MvcHtmlString.Create(raidobuttonStr);
        }

        /// <summary>
        /// 扩展 CheckBox 列表2
        /// </summary>
        /// <typeparam name="TModel">实体</typeparam>
        /// <typeparam name="TValue">属性</typeparam>
        /// <param name="helper"></param>
        /// <param name="expression">表达式</param>
        /// <param name="viewDataName">viewData数据列表名称</param>
        /// <param name="column">每行显示个数</param>
        /// <param name="attributes">属性</param>
        /// <returns></returns>
        public static MvcHtmlString CheckBoxListFor<TModel, TValue>(this HtmlHelper<TModel> helper, Expression<Func<TModel, TValue>> expression, string viewDataName, int column = 0, object attributes = null)
        {
            string raidobuttonStr = "";
            var items = helper.ViewData[viewDataName] as List<SelectListItem>;
            BuildListTag(out raidobuttonStr, "checkbox", items, expression, column, attributes);
            return MvcHtmlString.Create(raidobuttonStr);
        }

        /// <summary>
        /// 构造radioList或者checkBoxList标签
        /// </summary>
        /// <typeparam name="TModel"></typeparam>
        /// <typeparam name="TValue"></typeparam>
        /// <param name="raidobuttonStr">拼接的字符窜</param>
        /// <param name="tag">标签(checkbox or  radio)</param>
        /// <param name="expression">表达式</param>
        /// <param name="items">数据列表</param>
        /// <param name="column">每行显示个数</param>
        /// <param name="attributes">属性</param>
        private static void BuildListTag<TModel, TValue>(out string raidobuttonStr, string tag, IEnumerable<SelectListItem> items, Expression<Func<TModel, TValue>> expression, int column = 0, object attributes = null)
        {
            raidobuttonStr = "";
            if (items != null && items.Any())
            {
                int count = 1;
                ///获取表达式属性名称
                var name = (expression.Body as MemberExpression).Member.Name;
                foreach (var item in items)
                {
                    TagBuilder raidobutton = new TagBuilder("input");
                    raidobutton.Attributes.Add("type", tag);
                    raidobutton.Attributes.Add("name", name);
                    raidobutton.Attributes.Add("value", item.Value);
                    if (item.Selected)
                    {
                        raidobutton.Attributes.Add("checked", "checked");
                    }
                    if (attributes != null)
                    {
                        raidobutton.MergeAttributes(new RouteValueDictionary(attributes));
                    }

                    raidobuttonStr += raidobutton.ToString(TagRenderMode.SelfClosing);
                    raidobuttonStr += item.Text;
                    raidobuttonStr += "&nbsp;&nbsp;&nbsp;";

                    if (column == 1)
                    {
                        raidobuttonStr += "<br/>";
                    }
                    ///根据每行显示个数设置换行
                    else
                    {
                        if (count == column && column != 0)
                        {
                            raidobuttonStr += "<br/>";
                        }
                    }
                    count++;
                }
            }
        }
    }
}

使用方法：

@Html.CheckBoxListFor(item => item.AllRoles, "Roles", 5)
@Html.DropdownListFor(item => item.AllRoles, "Roles")
@Html.DropdownList("AllRoles", "Roles")
@Html.DropdownListFor(item => item.TypeID, ViewData["ArticleTypes"] as List<SelectListItem>)
还有其他的一些重载方法，我没有逐个写出，大家都可以试试。
http://www.cnblogs.com/artech/archive/2012/03/13/code-binding.html
http://www.cnblogs.com/a546558309/p/4554592.html