对象转JSON

        /// <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;
            }
        }