添加System.runtime.serialization.dll引用

public static class JsonSerializer
    {
        private static ITracing _tracing = TracingManager.GetTracing(typeof(JsonSerializer));


        /// <summary>
        /// 将指定对象序列化为 JavaScript 对象表示法 (JSON) 数据，并将生成的 JSON 写入流中。
        /// </summary>
        /// <typeparam name="T">对象类型</typeparam>
        /// <param name="stream">流对象</param>
        /// <param name="obj">序列化对象</param>
        public static void Serialize<T>(Stream stream, T obj)
        {
            JsonSerializeProxy<T>.Default.Serialize(stream, obj);
        }


        /// <summary>
        /// 将指定对象序列化为 JavaScript 对象表示法 (JSON) 数据，并返回对应的字符串。
        /// </summary>
        /// <typeparam name="T">对象类型</typeparam>
        /// <param name="obj">序列化对象</param>
        /// <returns>JavaScript 对象表示法 (JSON) 字符串</returns>
        public static string Serialize<T>(T obj)
        {
            using (MemoryStream ms = new MemoryStream())
            {
                JsonSerializeProxy<T>.Default.Serialize(ms, obj);


                string jsonStr = Encoding.UTF8.GetString(ms.ToArray());


                _tracing.InfoFmt("{0} json serialize result: {1}", typeof(T).ToString(), jsonStr);


                return jsonStr;
            }
        }


        public static T DeSerialize<T>(string jsonStr)
        {
            return JsonSerializeProxy<T>.Default.DeSerialize(jsonStr);
        }
    }


    public class JsonSerializeProxy<T>
    {
        private static readonly JsonSerializeProxy<T> _default = new JsonSerializeProxy<T>();
        private DataContractJsonSerializer _serializer;


        public static JsonSerializeProxy<T> Default
        {
            get
            {
                return _default;
            }
        }


        private JsonSerializeProxy()
        {
            _serializer = new DataContractJsonSerializer(typeof(T));
        }


        public void Serialize(Stream stream, T obj)
        {
            _serializer.WriteObject(stream, obj);
        }


        /// <summary>
        /// 将JSON字符串反序列化为对象
        /// </summary>
        /// <param name="jsonStr">json字符串</param>
        /// <returns></returns>
        public T DeSerialize(string jsonStr)
        {
            MemoryStream ms = new MemoryStream(Encoding.UTF8.GetBytes(jsonStr));
            T obj = (T)_serializer.ReadObject(ms);
            return obj;
        }


    }