MVC3 获取JSON对象

1.建一个mvc3的项目，取名叫MVC3Test（事先安装mvc3 version：1.13.113.0）

2.修改About.cshtml,如下代码
About.cshtml
@{
    ViewBag.Title = "About Us";
}
<script type="text/javascript">
    $(function () {
        $.ajax({
            url: "/Home/GetSchools",
            type: "POST",
            contentType: "application/json; charset=utf-8",
            data: "{}",
            dataType: "json",
            success: function (data) {
                $("#sltSchool").empty();
                $("#sltSchool").html(data);
            },
            error: function ErrorCallback(XMLHttpRequest, textStatus, errorThrown) {
                alert(errorThrown + ":" + textStatus);
            }
        });
        // Get the departments depend on the school
        $("#sltSchool").change(function () {
            GetDepartments($("#sltSchool").val());
        });
    });

    function GetDepartments(sId) {
        $.ajax({
            url: "/Home/GetSecondCatalog",
            type: "POST",
            contentType: "application/json; charset=utf-8",
            data: "{schoolId:"+sId+"}",
            dataType: "json",
            success: function (data) {
                $('#sltDepartment').empty();
                $('#sltDepartment').html(data);
            },
            error: function ErrorCallback(XMLHttpRequest, textStatus, errorThrown) {
                alert(errorThrown + ":" + textStatus);
            }
        });
    }
</script>
<div>
    <h2>
        About</h2>
    <p>
        Put content here.
    </p>
    <div>
        <span>
            <label>
                School :
            </label>
            <select id="sltSchool">
                <option value="-1">select...</option>
            </select></span> <span style="margin-left: 50px">
                <label>
                    Department :</label>
                <select id="sltDepartment">
                    <option value="-1">select...</option>
                </select>
            </span>
    </div>
</div>
3.创建几个model
 (1) TestSchool.cs
TestSchool
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;

namespace MVC3Test.Models
{
    public class TestSchool
    {
        public int Id { get; set; }
        public string Name { get; set; }
    }
}
 (2) TestSchoolDepartment.cs
TestSchoolDepartment.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;

namespace MVC3Test.Models
{
    public class TestSchoolDepartment
    {
        public int Id { get; set; }
        public int SchoolId { get; set; }
        public string Name { get; set; }
    }
}
 (3) TestModels.cs
TestModels.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;

namespace MVC3Test.Models
{
    public class TestModels
    {
        public static List<TestSchool> GetAllSchools()
        {
            return new List<TestSchool>()
            {
                new TestSchool{Id=1,Name="ABC"},
                new TestSchool{Id=2,Name="DEF"},
                new TestSchool{Id=3,Name="HIJ"},
                new TestSchool{Id=4,Name="LMN"}
            };
        }

        public static List<TestSchoolDepartment> GetAllDepartment()
        {
            return new List<TestSchoolDepartment>()
            {
                new TestSchoolDepartment{Id=1,SchoolId=1,Name="ABC_D1"},
                new TestSchoolDepartment{Id=2,SchoolId=1,Name="ABC_D2"},
                new TestSchoolDepartment{Id=3,SchoolId=1,Name="ABC_D3"},
                new TestSchoolDepartment{Id=4,SchoolId=2,Name="DEF_D1"},
                new TestSchoolDepartment{Id=5,SchoolId=2,Name="DEF_D2"},
                new TestSchoolDepartment{Id=6,SchoolId=3,Name="HIJ_D1"},
                new TestSchoolDepartment{Id=7,SchoolId=3,Name="HIJ_D2"},
                new TestSchoolDepartment{Id=8,SchoolId=3,Name="HIJ_D3"},
                new TestSchoolDepartment{Id=9,SchoolId=3,Name="HIJ_D4"},
                new TestSchoolDepartment{Id=10,SchoolId=4,Name="LMN_D1"}
            };
        }
 public static List<TestSchoolDepartment> GetDepartmentBySchoolId(int schoolId)
        {
List<TestSchoolDepartment> testSchoolDepartment = new List<TestSchoolDepartment>();
foreach (TestSchoolDepartment department in GetAllDepartment())
            {
                if (department.SchoolId == schoolId)
                {
                    testSchoolDepartment.Add(department);
                }
            }
            return testSchoolDepartment;
        }
    }
}
4.由于About是在Home页面里的，所以它的controller应该在HomeController里，我们添加两个controller，如下：
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Mvc;
using MVC3Test.Models;
using System.Text;

namespace MVC3Test.Controllers
{
    public class HomeController : Controller
    {
        public ActionResult Index()
        {
            ViewBag.Message = "Welcome to ASP.NET MVC!";

            return View();
        }

        public ActionResult About()
        {
            return View();
        }

        [HttpPost]
        public JsonResult GetSchools()
        {
            StringBuilder sb = new StringBuilder();
            sb.Append("<option value=\"-1\">select...</option>");
            foreach (var item in TestModels.GetAllSchools())
            {
sb.AppendFormat("<option value=\"{0}\">{1}</option>", item.Id, item.Name);
            }
            string result = sb.ToString();
            return this.Json(result, JsonRequestBehavior.AllowGet);
        }

        [HttpPost]
        public JsonResult GetSecondCatalog(int schoolId)
        {
            StringBuilder sb = new StringBuilder();
            sb.Append("<option value=\"-1\">select...</option>");
            foreach (var item in TestModels.GetDepartmentBySchoolId(schoolId))
            {
sb.AppendFormat("<option value=\"{0}\">{1}</option>", item.Id, item.Name);
            }
            string result = sb.ToString();
            return this.Json(result, JsonRequestBehavior.AllowGet);
        }
    }
}