使用Newtonsoft.Json这是一个开源的Json.Net库。

下载地址：。当前版本为 Release 8

从下载到的源代码中获取Newtonsoft.Json.Net20.dll,添加到自己的工程中。

using Newtonsoft.Json;

定义类:

 public class Message

    {

        public string Address { get; set; }

        [JsonProperty(TypeNameHandling = TypeNameHandling.All)]

        public object Body { get; set; }

    }

    public class SearchDetails

    {

        public string Query { get; set; }

        public string Language { get; set; }

    }

测试:

           Message message = new Message

            {

                Address = "",

                Body = new SearchDetails { Query = "Json.Net", Language = "en-us" }

            };

            string jsonMsg = JsonConvert.SerializeObject(message, Formatting.Indented);//Indented表示以缩进形式显示结果

            System.Diagnostics.Debug.Write(jsonMsg);

            Message deserialized = JsonConvert.DeserializeObject<Message>(jsonMsg);

            SearchDetails searchDetails = (SearchDetails)deserialized.Body;

            Response.Write(searchDetails.Query + "," + searchDetails.Language + "<br/>");

Debug输出结果格式：

{

  "Address": "",

  "Body": {

    "$type": "TestJsonSerialization.SearchDetails, TestJsonSerialization",

    "Query": "Json.Net",

    "Language": "en-us"

  }

}

注：1.JsonProperty标记字段或属性，用来控制它作为一个Json对象的属性序列化。

       2.TypeNameHandling 用来为Json序列化指定类型名。它有几个枚举值：

Member	Description
None	Do not include the .NET type name when serializing types.
Objects	Include the .NET type name when serializing into a JSON object structure.
Arrays	Include the .NET type name when serializing into a JSON array structure.
Auto	Include the .NET type name when the type of the object being serialized is not the same as its declared type.
All	Always include the .NET type name when serializing.