mvc使用Newtonsoft.Json反序列化json数据

mvc中默认使用的json返回序列化工具是JsonValueProviderFactory，JsonValueProviderFactory继承自ValueProviderFactory抽象类。JsonValueProviderFactory使用的序列化类库是System.Web.Script.Serialization。现在我们来写一个自己的方序列话工具，采用的是Newtonsoft.Json序列化和反序列化工具。

JsonValueProviderFactory代码具体如下：

using System;
using System.Collections;
using System.Collections.Generic;
using System.Dynamic;
using System.Globalization;
using System.IO;
using System.Web.Mvc;
using Newtonsoft.Json;
using Newtonsoft.Json.Converters;

namespace Aft.Build.MvcWeb.Common
{
    public class JsonNetValueProviderFactory : ValueProviderFactory
    {
        public override IValueProvider GetValueProvider(ControllerContext controllerContext)
        {
            // first make sure we have a valid context
            if (controllerContext == null)
                throw new ArgumentNullException("controllerContext");

            // now make sure we are dealing with a json request
            if (!controllerContext.HttpContext.Request.ContentType.StartsWith("application/json", StringComparison.OrdinalIgnoreCase))
                return null;

            // get a generic stream reader (get reader for the http stream)
            var streamReader = new StreamReader(controllerContext.HttpContext.Request.InputStream);
            // convert stream reader to a JSON Text Reader
            var jsonReader = new JsonTextReader(streamReader);
            // tell JSON to read
            if (!jsonReader.Read())
                return null;

            // make a new Json serializer
            var jsonSerializer = new JsonSerializer();
            // add the dyamic object converter to our serializer
            jsonSerializer.Converters.Add(new ExpandoObjectConverter());

            // use JSON.NET to deserialize object to a dynamic (expando) object
            Object jsonObject;
            // if we start with a "[", treat this as an array
            if (jsonReader.TokenType == JsonToken.StartArray)
                jsonObject = jsonSerializer.Deserialize<List<ExpandoObject>>(jsonReader);
            else
                jsonObject = jsonSerializer.Deserialize<ExpandoObject>(jsonReader);

            // create a backing store to hold all properties for this deserialization
            var backingStore = new Dictionary<string, object>(StringComparer.OrdinalIgnoreCase);
            // add all properties to this backing store
            AddToBackingStore(backingStore, String.Empty, jsonObject);
            // return the object in a dictionary value provider so the MVC understands it
            return new DictionaryValueProvider<object>(backingStore, CultureInfo.CurrentCulture);
        }

        private static void AddToBackingStore(Dictionary<string, object> backingStore, string prefix, object value)
        {
            var d = value as IDictionary<string, object>;
            if (d != null)
            {
                foreach (var entry in d)
                {
                    AddToBackingStore(backingStore, MakePropertyKey(prefix, entry.Key), entry.Value);
                }
                return;
            }

            var l = value as IList;
            if (l != null)
            {
                for (int i = 0; i < l.Count; i++)
                {
                    AddToBackingStore(backingStore, MakeArrayKey(prefix, i), l[i]);
                }
                return;
            }

            // primitive
            backingStore[prefix] = value;
        }

        private static string MakeArrayKey(string prefix, int index)
        {
            return prefix + "[" + index.ToString(CultureInfo.InvariantCulture) + "]";
        }

        private static string MakePropertyKey(string prefix, string propertyName)
        {
            return (String.IsNullOrEmpty(prefix)) ? propertyName : prefix + "." + propertyName;
        }
    }
}

然后把JsonValueProviderFactory注册给全局json数据反序列化使用：

在Global.asax文件Application_Start方法中添加如下两行代码：

ValueProviderFactories.Factories.Remove(ValueProviderFactories.Factories.OfType<JsonValueProviderFactory>().FirstOrDefault());
            ValueProviderFactories.Factories.Add(new JsonNetValueProviderFactory());

第一句是移除原来的JsonValueProviderFactory反序列化，第二句是添加自己的反序列化工具。

总结及注意事项：

1.mvc客户端数据到服务器段的数据类型转换都是在通过ValueProviderFactories来注册的。

2.切记mvc中通过ajax来传到服务器段的数据报文头记得一定要Content-Type:application/json，不然不会使用我们上面自己的JsonNetValueProviderFactory反序列化工具

mvc使用Newtonsoft.Json反序列化json数据