在第一篇文章中使用的json方法。能够依照须要仅仅处理须要的属性，但却要求属性不能是复杂的类型，比如泛型，数组。其它用户自己定义的类等，限制太多，于是自己看看能不能改进，想不到Newtonsoft.Json提供有相关的接口，仅仅须要实现就能够了。

仅仅须要继承DefaultContractResolver，并改写一个方法就能够了。

核心代码：

 /// <summary>
        /// 对象转为json，全部属性都输出
        /// </summary>
        /// <typeparam name="ObjType"></typeparam>
        /// <param name="obj"></param>
        /// <returns></returns>
        public static string ObjToJsonString<ObjType>(ObjType obj) where ObjType : class
        {
            string s = JsonConvert.SerializeObject(obj);
            return s;
        }
        /// <summary>
        /// 对象转为json，仅仅输出部分属性
        /// </summary>
        /// <typeparam name="T">对象类型</typeparam>
        /// <param name="t">对象类型值</param>
        /// <param name="propertyInfos">须要json处理的属性名称。以逗号分隔</param>
        /// <returns></returns>
        public static string ObjToJsonString<T>(T t, string propertyInfos) where T : class
        {
             string[] cols = propertyInfos.Split(new char[] { ‘,‘ }, StringSplitOptions.RemoveEmptyEntries);
             List<string> _propertyNames = new List<string>();
             foreach (string col in cols)
             {  
                 string   colTemp = col.ToLower().Trim();
                 if (!_propertyNames.Contains(colTemp))
                 {
                     _propertyNames.Add(colTemp);
                 }
             }
             string s = JsonConvert.SerializeObject(t, Formatting.Indented, new JsonSerializerSettings { ContractResolver = new DynamicContractResolver(_propertyNames) });
            return s;
        }
        /// <summary>
        /// json转为对象
        /// </summary>
        /// <typeparam name="ObjType"></typeparam>
        /// <param name="JsonString"></param>
        /// <returns></returns>
        public static ObjType JsonStringToObj<ObjType>(string JsonString) where ObjType : class
        {          
            ObjType s = JsonConvert.DeserializeObject<ObjType>(JsonString);
            return s;
        }
        class DynamicContractResolver : DefaultContractResolver
        {

            private readonly List<string> _propertyNames;
            public DynamicContractResolver(List<string> propertyNames)
            {
                _propertyNames = propertyNames;
            }
            /// <summary>
            /// 假设属性是对象。须要把这个对象的属性也传给propertyNames，
            /// 否则处理这个对象属性时，就不包括相应的属性值
            /// </summary>
            /// <param name="type"></param>
            /// <param name="memberSerialization"></param>
            /// <returns></returns>
            protected override IList<JsonProperty> CreateProperties(Type type, MemberSerialization memberSerialization)
            {
                IList<JsonProperty> properties = base.CreateProperties(type, memberSerialization);
                IList<JsonProperty> propertiesReturn = new List<JsonProperty>();//须要json处理的属性
                foreach (JsonProperty item in properties)
                { 
                    
                     string PropertyNameTemp = item.PropertyName.ToLower().Trim();
                    if (_propertyNames.Contains(PropertyNameTemp))
                    {
                        propertiesReturn.Add(item);                   
                    }
                }

                return propertiesReturn;
            }
        }