其他扩展方法详见：https://www.cnblogs.com/zhuanjiao/p/12060937.html

主要是是对日期格式的处理

using Newtonsoft.Json;
using Newtonsoft.Json.Converters;
using Newtonsoft.Json.Serialization;
using System;
using System.Collections.Generic;
using System.Reflection;

namespace CoSubject.Common.JsonNet
{
public static class NewtonsoftJsonSerializer
{
public static JsonSerializerSettings Settings { get; private set; }

    static NewtonsoftJsonSerializer()  
    {  
        Settings = new JsonSerializerSettings  
        {  
            Converters = new List<JsonConverter> { new IsoDateTimeConverter() },  
            ContractResolver = new CustomContractResolver(),  
            ConstructorHandling = ConstructorHandling.AllowNonPublicDefaultConstructor  
        };  
    }

    /// <summary>  
    /// Serialize an object to json string.  
    /// </summary>  
    /// <param name="obj"></param>  
    /// <returns></returns>  
    public static string Serialize(this object obj)  
    {  
        return obj == null ? null : JsonConvert.SerializeObject(obj, Settings);  
    }

    /// <summary>  
    /// Serialize an object to json string.  
    /// </summary>  
    /// <param name="obj"></param>  
    /// <param name="joinChar"></param>  
    /// <returns></returns>  
    public static string SerializeObjectTime(this object obj, string joinChar = "/")  
    {  
        Settings = new JsonSerializerSettings  
        {  
            Converters =  
                new List<JsonConverter>  
                {  
                    new IsoDateTimeConverter()  
                    {  
                        DateTimeFormat =  
                            string.Format( "yyyy{0}MM{0}dd HH:mm:ss",joinChar)  
                    }  
                },  
            ContractResolver = new CustomContractResolver(),  
            ConstructorHandling = ConstructorHandling.AllowNonPublicDefaultConstructor  
        };  
        return obj == null ? null : JsonConvert.SerializeObject(obj, Settings);  
    }

    public static string SerializeObjectTimeNoSecond(this object obj, string joinChar = "/")  
    {  
        Settings = new JsonSerializerSettings  
        {  
            Converters =  
                new List<JsonConverter>  
                {  
                    new IsoDateTimeConverter()  
                    {  
                        DateTimeFormat = string.Format( "yyyy{0}MM{0}dd HH:mm", joinChar)  
                    }  
                },  
            ContractResolver = new CustomContractResolver(),  
            ConstructorHandling = ConstructorHandling.AllowNonPublicDefaultConstructor  
        };  
        return obj == null ? null : JsonConvert.SerializeObject(obj, Settings);  
    }

    public static string SerializeObjectDate(this object obj, string joinChar = "/")  
    {  
        Settings = new JsonSerializerSettings  
        {  
            Converters =  
                new List<JsonConverter>  
                {  
                    new IsoDateTimeConverter()  
                    {  
                        DateTimeFormat = string.Format( "yyyy{0}MM{0}dd", joinChar)  
                    }  
                },  
            ContractResolver = new CustomContractResolver(),  
            ConstructorHandling = ConstructorHandling.AllowNonPublicDefaultConstructor  
        };  
        return obj == null ? null : JsonConvert.SerializeObject(obj, Settings);  
    }

    /// <summary>  
    /// Deserialize a json string to an object.  
    /// </summary>  
    /// <param name="value"></param>  
    /// <param name="type"></param>  
    /// <returns></returns>  
    public static object Deserialize(this string value, Type type)  
    {  
        return JsonConvert.DeserializeObject(value, type, Settings);  
    }

    /// <summary>  
    /// Deserialize a json string to a strong type object.  
    /// </summary>  
    /// <typeparam name="T"></typeparam>  
    /// <param name="value"></param>  
    /// <param name="joinChar"></param>  
    /// <returns></returns>  
    public static T Deserialize<T>(this string value, string joinChar = "/") where T : class  
    {  
        Settings = new JsonSerializerSettings  
        {  
            Converters = new List<JsonConverter> { new IsoDateTimeConverter() { DateTimeFormat = string.Format("yyyy{0}MM{0}dd", joinChar) } },  
            DateTimeZoneHandling = DateTimeZoneHandling.Utc  
        };  
        return JsonConvert.DeserializeObject<T>(value, Settings);  
    }

    /// <summary>  
    /// Deserialize a json string to a strong type object.  
    /// </summary>  
    /// <typeparam name="T"></typeparam>  
    /// <param name="value"></param>  
    /// <param name="joinChar"></param>  
    /// <returns></returns>  
    public static T DeserializeNoSecond<T>(this string value, string joinChar = "/") where T : class  
    {  
        Settings = new JsonSerializerSettings  
        {  
            Converters = new List<JsonConverter> { new IsoDateTimeConverter() { DateTimeFormat = string.Format("yyyy{0}MM{0}dd HH:mm", joinChar) } },  
            DateTimeZoneHandling = DateTimeZoneHandling.Utc  
        };  
        return JsonConvert.DeserializeObject<T>(value, Settings);  
    }

    class CustomContractResolver : DefaultContractResolver  
    {  
        protected override JsonProperty CreateProperty(MemberInfo member, MemberSerialization memberSerialization)  
        {  
            var jsonProperty = base.CreateProperty(member, memberSerialization);  
            if (jsonProperty.Writable) return jsonProperty;  
            var property = member as PropertyInfo;  
            if (property == null) return jsonProperty;  
            var hasPrivateSetter = property.GetSetMethod(true) != null;  
            jsonProperty.Writable = hasPrivateSetter;  
            return jsonProperty;  
        }  
    }  
}  

}