Code
//
// ObjectListToJSON
// Copyright (c) 2008 pcode. All rights reserved.
//
// Author(s):
//
//   pcode,jy@cjlu.edu.cn
// 此类用于将List<object>转换为json数据格式
// 目前仅能处理一个object的基础数据类型而且对[ { }] \等对json有伤害影响特殊符号没有特殊处理
// 希望有兄弟继续完善

using System.Reflection;
using System.Collections.Generic;

public class ObjectListToJSON
{
  #region 反射一个对象所有属性和属性值和将一个对象的反射结果封装成jsons格式
  /**
     * 对象的全部属性和属性值。用于填写json的{}内数据
     * 生成后的格式类似
     * "属性1":"属性值"
     * 将这些属性名和属性值写入字符串列表返回
     * */
  private List<string> GetObjectProperty(object o)
  {
    List<string> propertyslist = new List<string>();
    PropertyInfo[] propertys = o.GetType().GetProperties();
    foreach (PropertyInfo p in propertys)
    {
      propertyslist.Add("\"" + p.Name.ToString() + "\":\"" + p.GetValue(o, null) + "\"");
    }
    return propertyslist;
  }
  /**
   * 将一个对象的所有属性和属性值按json的格式要求输入为一个封装后的结果。
   *
   * 返回值类似{"属性1":"属性1值","属性2":"属性2值","属性3":"属性3值"}
   * 
   * */
  private string OneObjectToJSON(object o)
  {
    string result = "{";
    List<string> ls_propertys = new List<string>();
    ls_propertys = GetObjectProperty(o);
    foreach (string str_property in ls_propertys)
    {
      if (result.Equals("{"))
      {
        result = result + str_property;
      }
      else
      {
        result = result + "," + str_property + "";
      }
    }
    return result + "}";
  }
  #endregion
  /**
     * 把对象列表转换成json串
     * */
  public string toJSON(List<object> objlist)
  {//覆写，给懒人一个不写classname的机会
    return toJSON(objlist, string.Empty);
  }
  public string toJSON(List<object> objlist, string classname)
  {
    string result = "{";
    if (classname.Equals(string.Empty))//如果没有给定类的名称，那么自做聪明地安一个
    {
      object o = objlist[0]
      classname = o.GetType().ToString();
    }
    result += "\"" + classname + "\":[";
    bool firstline = true;//处理第一行前面不加","号
    foreach (object oo in objlist)
    {
      if (!firstline)
      {
        result = result + "," + OneObjectToJSON(oo);
      }
      else
      {
        result = result + OneObjectToJSON(oo) + "";
        firstline = false;
      }
    }
    return result + "]}";
  }

}

namespace Model
{
  public class Person
  {
    public string ID { get; set; }
    public string Name { get; set; }
    public string Sex { get; set; }
  }
}

using NUnit.Framework;
using System.Collections.Generic;
namespace JSon
{
  [TestFixture]
  public class TestObjectToJSON
  {
    [Test]
    public void dotest() {
      Model.Person p1 = new Model.Person();
      p1.ID = "1";
      p1.Name = "p1";
      p1.Sex = "s1";
      Model.Person p2 = new Model.Person();
      p2.ID = "2";
      p2.Name = "p2";
      p2.Sex = "s2";

      Model.Person p3 = new Model.Person();
      p3.ID = "3";
      p3.Name = "p3";
      p3.Sex = "s3";
      List<object> lp = new List<object>();
      lp.Add(p1);
      lp.Add(p2);
      lp.Add(p3);

      ObjectListToJSON t = new ObjectListToJSON();
      string json = t.toJSON(lp, "persons");
      System.Console.Write(json);
    }
  }
}