艾斯伊の筆記

● JSON格式

1.在Global.asax.cs的Application_Start中加入

GlobalConfiguration .Configuration.Formatters.XmlFormatter.SupportedMediaTypes.Clear();

 

---

● JSONP格式

1.在NuGet中加入WebApiContrib.Formatting.Jsonp

2.在App_Start中加入JsonpFormatter.cs

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

// 請替換掉<Your Namespace>
namespace <Your Namespace>
{
    /// <summary>    
    /// Handles JsonP requests when requests are fired with text/javascript    
    /// </summary>    
    public class JsonpFormatter : JsonMediaTypeFormatter
    {

        public JsonpFormatter()
        {
            SupportedMediaTypes.Add(new MediaTypeHeaderValue("application/json"));
            SupportedMediaTypes.Add(new MediaTypeHeaderValue("text/javascript"));

            JsonpParameterName = "callback";
        }

        /// <summary>    
        ///  Name of the query string parameter to look for    
        ///  the jsonp function name    
        /// </summary>    
        public string JsonpParameterName { get; set; }

        /// <summary>    
        /// Captured name of the Jsonp function that the JSON call    
        /// is wrapped in. Set in GetPerRequestFormatter Instance    
        /// </summary>    
        private string JsonpCallbackFunction;


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

        /// <summary>    
        /// Override this method to capture the Request object    
        /// </summary>    
        /// <param name="type"></param>    
        /// <param name="request"></param>    
        /// <param name="mediaType"></param>    
        /// <returns></returns>    
        public override MediaTypeFormatter GetPerRequestFormatterInstance(Type type, HttpRequestMessage request, MediaTypeHeaderValue mediaType)
        {
            var formatter = new JsonpFormatter()
            {
                JsonpCallbackFunction = GetJsonCallbackFunction(request)
            };

            // this doesn't work unfortunately    
            //formatter.SerializerSettings = GlobalConfiguration.Configuration.Formatters.JsonFormatter.SerializerSettings;    

            // You have to reapply any JSON.NET default serializer Customizations here        
            formatter.SerializerSettings.Converters.Add(new StringEnumConverter());
            formatter.SerializerSettings.Formatting = Newtonsoft.Json.Formatting.Indented;

            return formatter;
        }


        public override Task WriteToStreamAsync(Type type, object value,
                                        Stream stream,
                                        HttpContent content,
                                        TransportContext transportContext)
        {
            if (string.IsNullOrEmpty(JsonpCallbackFunction))
                return base.WriteToStreamAsync(type, value, stream, content, transportContext);

            StreamWriter writer = null;

            // write the pre-amble    
            try
            {
                writer = new StreamWriter(stream);
                writer.Write(JsonpCallbackFunction + "(");
                writer.Flush();
            }
            catch (Exception ex)
            {
                try
                {
                    if (writer != null)
                        writer.Dispose();
                }
                catch { }

                var tcs = new TaskCompletionSource<object>();
                tcs.SetException(ex);
                return tcs.Task;
            }

            return base.WriteToStreamAsync(type, value, stream, content, transportContext)
                       .ContinueWith(innerTask =>
                       {
                           if (innerTask.Status == TaskStatus.RanToCompletion)
                           {
                               writer.Write(")");
                               writer.Flush();
                           }
                           writer.Dispose();
                           return innerTask;
                       }, TaskContinuationOptions.ExecuteSynchronously)
                            .Unwrap();
        }

        /// <summary>    
        /// Retrieves the Jsonp Callback function    
        /// from the query string    
        /// </summary>    
        /// <returns></returns>    
        private string GetJsonCallbackFunction(HttpRequestMessage request)
        {
            if (request.Method != HttpMethod.Get)
                return null;

            var query = HttpUtility.ParseQueryString(request.RequestUri.Query);
            var queryVal = query[this.JsonpParameterName];

            if (string.IsNullOrEmpty(queryVal))
                return null;

            return queryVal;
        }
    }
}

3.在Global.asax.cs中加入

GlobalConfiguration.Configuration.Formatters.Clear();
GlobalConfiguration.Configuration.Formatters.Add(new JsonpMediaTypeFormatter(new JsonMediaTypeFormatter()));
GlobalConfiguration.Configuration.Formatters.Insert(0, new App_Start.JsonpFormatter());

 

---

參考網站：

http://blog.miniasp.com/post/2012/10/12/ASPNET-Web-API-Force-return-JSON-format-instead-of-XML-for-Google-Chrome-Firefox-Safari.aspx
http://www.cnblogs.com/broxten/archive/2013/06/06/3395811.html