WebAPi 用Newtonsoft.Json替换Syetem.json

WebApi原本的System存在一些对象Serializer不了的问题，可以用 用Newtonsoft.Json替换Syetem.json

using System;
using System.IO;
using System.Net;
using System.Net.Http.Formatting;
using System.Net.Http.Headers;
using System.Text;
using System.Threading.Tasks;
using Newtonsoft.Json;

namespace JsonNetSample.Formatters
{
    public class JsonNetFormatter : MediaTypeFormatter
    {
        private JsonSerializerSettings _jsonSerializerSettings;

        public JsonNetFormatter(JsonSerializerSettings jsonSerializerSettings)
        {
            _jsonSerializerSettings = jsonSerializerSettings ?? new JsonSerializerSettings();

            // Fill out the mediatype and encoding we support
            SupportedMediaTypes.Add(new MediaTypeHeaderValue("application/json"));
            Encoding = new UTF8Encoding(false, true);
        }

        protected override bool CanReadType(Type type)
        {
            if (type == typeof(IKeyValueModel))
            {
                return false;
            }

            return true;
        }

        protected override bool CanWriteType(Type type)
        {
            return true;
        }

        protected override Task<object> OnReadFromStreamAsync(Type type, Stream stream, HttpContentHeaders contentHeaders, FormatterContext formatterContext)
        {
            // Create a serializer
            JsonSerializer serializer = JsonSerializer.Create(_jsonSerializerSettings);

            // Create task reading the content
            return Task.Factory.StartNew(() =>
            {
                using (StreamReader streamReader = new StreamReader(stream, Encoding))
                {
                    using (JsonTextReader jsonTextReader = new JsonTextReader(streamReader))
                    {
                        return serializer.Deserialize(jsonTextReader, type);
                    }
                }
            });
        }

        protected override Task OnWriteToStreamAsync(Type type, object value, Stream stream, HttpContentHeaders contentHeaders, FormatterContext formatterContext, TransportContext transportContext)
        {
            // Create a serializer
            JsonSerializer serializer = JsonSerializer.Create(_jsonSerializerSettings);

            // Create task writing the serialized content
            return Task.Factory.StartNew(() =>
            {
                using (StreamWriter streamWriter = new StreamWriter(stream, Encoding))
                {
                    using (JsonTextWriter jsonTextWriter = new JsonTextWriter(streamWriter))
                    {
                        serializer.Serialize(jsonTextWriter, value);
                    }
                }
            });
        }
    }
}

protected void Application_Start(object sender, EventArgs e)
{

    // Action based routing (used for RPC calls)
    RouteTable.Routes.MapHttpRoute(
        name: "StockApi",
        routeTemplate: "stocks/{action}/{symbol}",
        defaults: new
        {
            symbol = RouteParameter.Optional,
            controller = "StockApi"
        }
    );
    // WebApi Configuration to hook up formatters and message handlers
    // optional
    RegisterApis(GlobalConfiguration.Configuration);
}

public static void RegisterApis(HttpConfiguration config)
{
    // Add JavaScriptSerializer  formatter instead - add at top to make default
    //config.Formatters.Insert(0, new JavaScriptSerializerFormatter());
    
    // Add Json.net formatter - add at the top so it fires first!
    // This leaves the old one in place so JsonValue/JsonObject/JsonArray still are handled
    config.Formatters.Insert(0, new JsonNetFormatter());
}

这样启动网站就OK了