Asp.net MVC4 下二级联动

效果图：

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sBTICdQOYCdgKZC9gJZC5gJ5C5gJ1A5gJ2ApkL2AlkLmAnkLmAnUDmAnYCmQvYCWQuYCeQuYCdQOYCdgKZy38AHVLCsLJuR8cAAAAASUVORK5CYII=" 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主要文件有Index.cshtml ,ErJLDController.cs ，还有数据库文件 。

1、首先在数据库中创建省级、城市的表，我的表如下：我用了一张表放下了省级、城市的数据，用level划分省份和城市，parentId表示该城市所在省份的id

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" alt="" />

 namespace Mvcproject.Controllers
 {
     //二级联动
     public class ErJLDController : Controller
     {

         ZjbEntities db = new ZjbEntities();
         //
         // GET: /Test/

         public ActionResult Index()
         {
             //pro_city province=new pro_city();

             return View();
         }

         public JsonResult getProvince() {

             List<pro_city> provinceList = (from p in db.pro_city where p.level == 1 select p).ToList();

             JsonResult Jprovince = new JsonResult();
             Jprovince.Data = provinceList;
             Jprovince.JsonRequestBehavior = JsonRequestBehavior.AllowGet;
             return Jprovince;

         }

         public JsonResult getCity(string pName)
         {

             //string pid = (from p in db.pro_city where p.areaValue == pName select p.id).ToString();
             //int id = int.Parse(pid);
             int id = int.Parse(pName);

             List<pro_city> cityList = (from p in db.pro_city where p.parentId == id select p).ToList();

             JsonResult Jcity = new JsonResult();
             Jcity.Data = cityList;
             Jcity.JsonRequestBehavior = JsonRequestBehavior.AllowGet;
             return Jcity;

         }

     }
 }

ErJLDController.cs

 <body>
     <div>
         <select id="provinceId" >
          <option> 请选择省份</option>
         </select>
         <select id="cityId">
             <option>请选择市区</option>
         </select>
     </div>

     <script type="text/javascript">

         //用json从数据库里取一级列表的参数
         $(function () {

             $.getJSON("ErJLD/getProvince/", function (obj) {
                 $.each(obj, function (i, p) {
                     $("#provinceId").append("<option value='"+p.id+"'>" + p.areaValue + "</option>");
                 });

                 $("#provinceId").change(function () {
                     //用attr（）方法获取当前选择的option的value值（即p.id ,数据库里的id值，
                     //虽然在TestController中的getCity方法中传入的是string类型的形参，但是后来需要变换成int类型, 所以value值应该为数字）
                     var pName = $("#provinceId").attr("value");
                     $.getJSON("ErJLD/getCity?pName=" + pName, getcity);
                 });
             });
         });

         function getcity(obj) {
             $("#cityId").empty();
                         $.each(obj, function (m, v) {
                             $("#cityId").append("<option >" + v.areaValue + "</option>");
                         });

                     };

     </script>
 </body>

Index.cshtml