using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Runtime.Serialization.Json;
using System.IO;
namespace JsonTest
{
  class JsonHelp
  {
    public JsonHelp()
  {

    //

    // TODO: Add constructor logic here

    //

  }
  /// <summary>
  /// 把对象序列化 JSON 字符串 
  /// </summary>
  /// <typeparam name="T">对象类型</typeparam>
  /// <param name="obj">对象实体</param>
  /// <returns>JSON字符串</returns>
  public static string GetJson<T>(T obj)
  {
    //记住 添加引用 System.ServiceModel.Web 
    /**
     * 如果不添加上面的引用,System.Runtime.Serialization.Json; Json是出不来的哦
     * */
    DataContractJsonSerializer json = new DataContractJsonSerializer(typeof(T));
    using (MemoryStream ms = new MemoryStream())
    {
      json.WriteObject(ms, obj);
      string szJson = Encoding.UTF8.GetString(ms.ToArray());
      return szJson;

    }

  }

  /// <summary>
  /// 把JSON字符串还原为对象
  /// </summary>
  /// <typeparam name="T">对象类型</typeparam>
  /// <param name="szJson">JSON字符串</param>
  /// <returns>对象实体</returns>
  public static T ParseFormJson<T>(string szJson)
  {
    T obj = Activator.CreateInstance<T>();
    using (MemoryStream ms = new MemoryStream (Encoding.UTF8.GetBytes(szJson)))
    {
      DataContractJsonSerializer dcj = new DataContractJsonSerializer(typeof(T));
      return (T)dcj.ReadObject(ms);
    }
  }
 

  }

} 

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace JsonTest
{
 public class testData
  {
    public testData()

  {

  }
  public int Id { get; set; }
  public string Name { get; set; }
  public string Sex { get; set; }
  }
} 

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace JsonTest

{
  class Program

  {
    static void Main(string[] args)
    {

      //实体类转json
      testData t1 = new testData();
      t1.Id = 1;
      t1.Name = "001姓名";
      t1.Sex = "男";
      testData t2 = new testData();
      t2.Id = 2;
      t2.Name = "002姓名";
      t2.Sex = "男";
      testData t3 = new testData();
      t3.Id = 3;
      t3.Name = "003姓名";
      t3.Sex = "男";
      List<testData> tlist = new List<testData>();
      tlist.Add(t1);
      tlist.Add(t2);
      tlist.Add(t3);
     Console.WriteLine(JsonHelp.GetJson<List<testData>>(tlist));

      // Console.ReadKey();
      //json转实体类

     List<testData> tl = JsonHelp.ParseFormJson <List<testData>>(JsonHelp.GetJson<List<testData>>(tlist));
     Console.WriteLine(tl.Count);
     Console.WriteLine(tl[0].Name);
     Console.ReadKey();
    }

  }
}