爱上MVC~为CheckBoxFor和RadioButtonFor加个扩展方法吧（希望MVC5把这方法收纳——呵呵）

说在前

我都是喜欢把问题复杂化，还有总是喜欢把问题简单化，偷懒化，这也需就是一个程序员的追求吧，呵呵。

我不太喜欢重复的东西，当你看到页面上有一个以上相同的代码时，那可以说，你的代码有重构的余地，应该考虑重构了，今天看了以前同事的博客，写了关于DropDownList的用法，如何将集合数据绑定到下拉列表框上，讲的不错，但最后在说checkbox和radiobutton时，我感觉有点重复了，我说的是代码重复了，还有就是代码复杂化了，就是说，我再使用集合来产生checkbox和radiobutton时，代码有些复杂了，这不是我们希望看到的，所以，我觉得有必要把它重构一下，为mvc加两个扩展方法吧，呵呵。

做在后

DropDownListFor的方法签名做的不错，很面向对象，很简洁，但不知不何，checkbox和radiobutton确没有这样的重载，呵呵

        public static MvcHtmlString DropDownListFor<TModel, TProperty>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TProperty>> expression, IEnumerable<SelectListItem> selectList);
        public static MvcHtmlString DropDownListFor<TModel, TProperty>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TProperty>> expression, IEnumerable<SelectListItem> selectList, IDictionary<string, object> htmlAttributes);
        public static MvcHtmlString DropDownListFor<TModel, TProperty>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TProperty>> expression, IEnumerable<SelectListItem> selectList, object htmlAttributes);
        public static MvcHtmlString DropDownListFor<TModel, TProperty>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TProperty>> expression, IEnumerable<SelectListItem> selectList, string optionLabel);
        public static MvcHtmlString DropDownListFor<TModel, TProperty>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TProperty>> expression, IEnumerable<SelectListItem> selectList, string optionLabel, IDictionary<string, object> htmlAttributes);
        public static MvcHtmlString DropDownListFor<TModel, TProperty>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TProperty>> expression, IEnumerable<SelectListItem> selectList, string optionLabel, object htmlAttributes);

对于checkbox和radiobutton它们只有简单的几个重载，没有对集合的支持，所以，我的这次代码扩展，主要是针对集合来说的，看方法签名：

下面看一下原代码，它直接写在了System.Web.Mvc命名空间下，这更说明我是对微软MVC的一个扩展，希望MVC5出来时，可以把这些都集成进去，呵呵

#region 单选框和复选框的扩展
        /// <summary>
        /// 复选框,selValue为选中项
        /// </summary>
        /// <param name="htmlHelper"></param>
        /// <param name="name"></param>
        /// <param name="selectList"></param>
        /// <param name="selValue"></param>
        /// <returns></returns>
        public static MvcHtmlString CheckBox(this HtmlHelper htmlHelper, string name, IEnumerable<SelectListItem> selectList, IEnumerable<string> selValue)
        {
            return CheckBoxAndRadioFor<object, string>(name, selectList, false, selValue);
        }
        public static MvcHtmlString CheckBox(this HtmlHelper htmlHelper, string name, IEnumerable<SelectListItem> selectList, string selValue)
        {
            return CheckBox(htmlHelper, name, selectList, new List<string> { selValue });

        }
        /// <summary>
        /// 复选框
        /// </summary>
        /// <param name="htmlHelper"></param>
        /// <param name="name"></param>
        /// <param name="selectList"></param>
        /// <returns></returns>
        public static MvcHtmlString CheckBoxFor(this HtmlHelper htmlHelper, string name, IEnumerable<SelectListItem> selectList)
        {
            return CheckBox(htmlHelper, name, selectList, new List<string>());
        }
        /// <summary>
        /// 根据列表输出checkbox
        /// </summary>
        /// <typeparam name="TModel"></typeparam>
        /// <typeparam name="TProperty"></typeparam>
        /// <param name="htmlHelper"></param>
        /// <param name="expression"></param>
        /// <param name="selectList"></param>
        /// <returns></returns>
        public static MvcHtmlString CheckBoxFor<TModel, TProperty>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TProperty>> expression, IEnumerable<SelectListItem> selectList)
        {
            return CheckBoxFor(htmlHelper, expression, selectList, null);
        }

        /// <summary>
        ///  根据列表输出checkbox,selValue为默认选中的项
        /// </summary>
        /// <typeparam name="TModel"></typeparam>
        /// <typeparam name="TProperty"></typeparam>
        /// <param name="htmlHelper"></param>
        /// <param name="expression"></param>
        /// <param name="selectList"></param>
        /// <param name="selValue"></param>
        /// <returns></returns>
        public static MvcHtmlString CheckBoxFor<TModel, TProperty>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TProperty>> expression, IEnumerable<SelectListItem> selectList, string selValue)
        {
            string name = ExpressionHelper.GetExpressionText(expression);
            return CheckBoxAndRadioFor<TModel, TProperty>(name, selectList, false, new List<string> { selValue });
        }
        /// <summary>
        /// 输出单选框和复选框
        /// </summary>
        /// <typeparam name="TModel"></typeparam>
        /// <typeparam name="TProperty"></typeparam>
        /// <param name="expression"></param>
        /// <param name="selectList"></param>
        /// <param name="isRadio"></param>
        /// <param name="selValue"></param>
        /// <returns></returns>
        static MvcHtmlString CheckBoxAndRadioFor<TModel, TProperty>(
            string name,
            IEnumerable<SelectListItem> selectList,
            bool isRadio,
            IEnumerable<string> selValue)
        {
            StringBuilder str = new StringBuilder();
            int c = 0;
            string check, activeClass;
            string type = isRadio ? "Radio" : "checkbox";

            foreach (var item in selectList)
            {
                c++;
                if (selValue != null && selValue.Contains(item.Value))
                {
                    check = "checked='checked'";
                    activeClass = "style=color:red";
                }
                else
                {
                    check = string.Empty;
                    activeClass = string.Empty;
                }
                str.AppendFormat("<span><input type='{3}' value='{0}' name={1} id={1}{2} " + check + "/>", item.Value, name, c, type);
                str.AppendFormat("<label for='{0}{1}' {3}>{2}</lable></span>", name, c, item.Text, activeClass);

            }
            return MvcHtmlString.Create(str.ToString());
        }


        public static MvcHtmlString RadioButton(this HtmlHelper htmlHelper, string name, IEnumerable<SelectListItem> selectList, IEnumerable<string> selValue)
        {
            return CheckBoxAndRadioFor<object, string>(name, selectList, true, selValue);
        }
        /// <summary>
        /// 单选按钮组，seletList为选中项
        /// </summary>
        /// <param name="htmlHelper"></param>
        /// <param name="name"></param>
        /// <param name="selectList"></param>
        /// <param name="selValue"></param>
        /// <returns></returns>
        public static MvcHtmlString RadioButton(this HtmlHelper htmlHelper, string name, IEnumerable<SelectListItem> selectList, string selValue)
        {
            return RadioButton(htmlHelper, name, selectList, new List<string> { selValue });
        }
        /// <summary>
        /// 单选按钮组
        /// </summary>
        /// <param name="htmlHelper"></param>
        /// <param name="name"></param>
        /// <param name="selectList"></param>
        /// <returns></returns>
        public static MvcHtmlString RadioButton(this HtmlHelper htmlHelper, string name, IEnumerable<SelectListItem> selectList)
        {
            return RadioButton(htmlHelper, name, selectList, new List<string>());
        }
        /// <summary>
        ///  根据列表输出radiobutton
        /// </summary>
        /// <typeparam name="TModel"></typeparam>
        /// <typeparam name="TProperty"></typeparam>
        /// <param name="htmlHelper"></param>
        /// <param name="expression"></param>
        /// <param name="selectList"></param>
        /// <returns></returns>
        public static MvcHtmlString RadioButtonFor<TModel, TProperty>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TProperty>> expression, IEnumerable<SelectListItem> selectList)
        {
            return RadioButtonFor(htmlHelper, expression, selectList, new List<string>());
        }
        public static MvcHtmlString RadioButtonFor<TModel, TProperty>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TProperty>> expression, IEnumerable<SelectListItem> selectList, IEnumerable<string> selValue)
        {
            string name = ExpressionHelper.GetExpressionText(expression);
            return CheckBoxAndRadioFor<TModel, TProperty>(name, selectList, true, selValue);
        }
        /// <summary>
        /// 根据列表输出radiobutton,selValue为默认选中的项
        /// </summary>
        /// <typeparam name="TModel"></typeparam>
        /// <typeparam name="TProperty"></typeparam>
        /// <param name="htmlHelper"></param>
        /// <param name="expression"></param>
        /// <param name="selectList"></param>
        /// <param name="selValue"></param>
        /// <returns></returns>
        public static MvcHtmlString RadioButtonFor<TModel, TProperty>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TProperty>> expression, IEnumerable<SelectListItem> selectList, string selValue)
        {
            return RadioButtonFor(htmlHelper, expression, selectList, new List<string> { selValue });
        }
        #endregion