.net實體類與json相互轉換時，注意要點：
1.jsonhelp編寫時候添加的引用。System.Runtime.Serialization.Json; 
2.實體類需聲明為public 

jsonhelp代碼： 

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>  /// 把對象序列化 JSON 字符串   /// </summary>  /// <typeparam name="T">對象類型</typeparam>  /// <param name="obj">對象實體</param>  /// <returns>JSON字符串</returns>  public static string GetJson<T>(T obj)  {    //記住 添加引用 System.ServiceModel.Web     /**     * 如果不添加上面的引用,System.Runtime.Serialization.Json; Json是出不來的哦     * */    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字符串還原為對象  /// </summary>  /// <typeparam name="T">對象類型</typeparam>  /// <param name="szJson">JSON字符串</param>  /// <returns>對象實體</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);    }  }   }} 

實體類代碼： 

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; }  }} 

控制臺應用程序測試代碼： 

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)    {      //實體類轉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轉實體類     List<testData> tl = JsonHelp.ParseFormJson <List<testData>>(JsonHelp.GetJson<List<testData>>(tlist));     Console.WriteLine(tl.Count);     Console.WriteLine(tl[0].Name);     Console.ReadKey();    }  }}