@html.DropDownList关于它的使用

var r = new List<Vendor>()             {                 new Vendor() {VendorId = 1, Name = "a"},                 new Vendor() {VendorId = 2, Name = "b"},                 new Vendor() {VendorId = 3, Name = "c"},                 new Vendor() {VendorId = 4, Name = "d"},                 new Vendor() {VendorId = 5, Name = "e"},             };             //将Vendor的数据封装到 SelectList中，制定要生成下拉框选项的value和text属性               SelectList selList1 = new SelectList(r, "VendorId", "Name", 0);             //把生成的集合放到ViewData中               ViewData["Categories"] = selList1; @Html.DropDownList("myselect", (SelectList)ViewData["Categories"],  "--请选择供应商--")                                                    @* @Html.DropDownListFor(a => a.CategoryName, (SelectList)ViewData["Categories"], "--Select One--", new { @class = "dropdownlist" })*@