可能是一个愚蠢的问题，但我正在尝试为我的webapi应用添加jsonp支持。我将此行添加到我的webapiconfig.cs中，但它失败了，因为jsonpmediatypeformatter构造函数需要2个参数：
public static void Register(HttpConfiguration configuration)
{
configuration.Routes.MapHttpRoute("API Default", "api/v1/{controller}/{id}",
new { id = RouteParameter.Optional });
var appXmlType = configuration.Formatters.XmlFormatter.SupportedMediaTypes.FirstOrDefault(t => t.MediaType == "application/xml");
configuration.Formatters.XmlFormatter.SupportedMediaTypes.Remove(appXmlType);
**configuration.Formatters.Insert(0, new JsonpMediaTypeFormatter();**
}
第一个似乎是mediatypeformatter类型，这对我来说没有多大意义。我试过了：
configuration.Formatters.Insert(0, new JsonpMediaTypeFormatter(new JsonMediaTypeFormatter(),"jsonp"));
可以正确地将响应包装在一个名为jsonp的函数中，但也会破坏标准的json响应。
有什么想法吗？
答案 0 :(得分：2)
我花了很长时间才开始工作。此代码基于https://gist.github.com/ninnemana/3715076 - 这对我不起作用，因为HttpContext.Current在4.5版本的.NET框架中返回null。
这是班级：
public class JsonpMediaTypeFormatter : JsonMediaTypeFormatter
{
private string _callbackQueryParamter;
private HttpRequestMessage HttpRequest;
public JsonpMediaTypeFormatter()
{
SupportedMediaTypes.Add(DefaultMediaType);
SupportedMediaTypes.Add(new MediaTypeWithQualityHeaderValue("text/javascript"));
MediaTypeMappings.Add(new UriPathExtensionMapping("jsonp", DefaultMediaType));
}
public string CallbackQueryParameter
{
get { return _callbackQueryParamter ?? "callback"; }
set { _callbackQueryParamter = value; }
}
public override MediaTypeFormatter GetPerRequestFormatterInstance(Type type,
HttpRequestMessage request, MediaTypeHeaderValue mediaType)
{
HttpRequest = request;
return base.GetPerRequestFormatterInstance(type, request, mediaType);
}
public override System.Threading.Tasks.Task WriteToStreamAsync(Type type, object value, System.IO.Stream writeStream, System.Net.Http.HttpContent content, System.Net.TransportContext transportContext)
{
string callback;
if (IsJsonpRequest(out callback))
{
return Task.Factory.StartNew(() =>
{
var writer = new StreamWriter(writeStream);
writer.Write(callback + "(");
writer.Flush();
base.WriteToStreamAsync(type, value, writeStream, content, transportContext).Wait();
writer.Write(")");
writer.Flush();
});
}
return base.WriteToStreamAsync(type, value, writeStream, content, transportContext);
}
private bool IsJsonpRequest(out string callback)
{
var query = HttpUtility.ParseQueryString(HttpRequest.RequestUri.Query);
callback = query[CallbackQueryParameter];
return !string.IsNullOrEmpty(callback);
}
}
这需要添加到你的创业公司：
public class Startup
{
// This code configures Web API. The Startup class is specified as a type
// parameter in the WebApp.Start method.
public void Configuration(IAppBuilder appBuilder)
{
// Configure Web API for self-host.
HttpConfiguration config = new HttpConfiguration();
// Remove the XML formatter (only want JSON) see http://www.asp.net/web-api/overview/formats-and-model-binding/json-and-xml-serialization
config.Formatters.Remove(config.Formatters.XmlFormatter);
// add jsonp formatter as the one with the highest prio
config.Formatters.Insert(0, new JsonpMediaTypeFormatter());
// routes
config.Routes.MapHttpRoute(
name: "DefaultApi",
routeTemplate: "api/{controller}/{arg1}/{arg2}",
defaults: new { arg1 = RouteParameter.Optional, arg2 = RouteParameter.Optional }
);
appBuilder.UseWebApi(config);
}
}
答案 1 :(得分：1)
所以，我已经阅读了大量关于向WebAPI添加JSONP支持的内容。我试过了所有这些。
然后，我花时间阅读我一直在使用的常规Json格式化程序......嘿，它也支持Jsonp。
这是班级：
public class JsonNetFormatter : MediaTypeFormatter
{
private readonly JsonSerializerSettings _jsonSerializerSettings;
private string _callbackQueryParameter;
public JsonNetFormatter(JsonSerializerSettings jsonSerializerSettings)
{
_jsonSerializerSettings = jsonSerializerSettings ?? new JsonSerializerSettings();
// Fill out the mediatype and encoding we support
SupportedMediaTypes.Add(new MediaTypeHeaderValue("application/json"));
SupportedEncodings.Add(new UTF8Encoding(false, true));
//we also support jsonp.
SupportedMediaTypes.Add(new MediaTypeHeaderValue("text/javascript"));
}
private Encoding Encoding
{
get { return SupportedEncodings[0]; }
}
public string CallbackQueryParameter
{
get { return _callbackQueryParameter ?? "callback"; }
set { _callbackQueryParameter = value; }
}
public override bool CanReadType(Type type)
{
return true;
}
public override bool CanWriteType(Type type)
{
return true;
}
public override MediaTypeFormatter GetPerRequestFormatterInstance(Type type,
HttpRequestMessage request,
MediaTypeHeaderValue mediaType)
{
var formatter = new JsonNetFormatter(_jsonSerializerSettings)
{
JsonpCallbackFunction = GetJsonCallbackFunction(request)
};
return formatter;
}
private string GetJsonCallbackFunction(HttpRequestMessage request)
{
if (request.Method != HttpMethod.Get)
return null;
var query = HttpUtility.ParseQueryString(request.RequestUri.Query);
var queryVal = query[CallbackQueryParameter];
if (string.IsNullOrEmpty(queryVal))
return null;
return queryVal;
}
private string JsonpCallbackFunction { get; set; }
public override Task<object> ReadFromStreamAsync(Type type, Stream readStream, HttpContent content, IFormatterLogger formatterLogger)
{
// Create a serializer
JsonSerializer serializer = JsonSerializer.Create(_jsonSerializerSettings);
// Create task reading the content
return Task.Factory.StartNew(() =>
{
using (var streamReader = new StreamReader(readStream, SupportedEncodings[0]))
{
using (var jsonTextReader = new JsonTextReader(streamReader))
{
return serializer.Deserialize(jsonTextReader, type);
}
}
});
}
public override Task WriteToStreamAsync(Type type, object value, Stream writeStream, HttpContent content, TransportContext transportContext)
{
var isJsonp = JsonpCallbackFunction != null;
// Create a serializer
JsonSerializer serializer = JsonSerializer.Create(_jsonSerializerSettings);
// Create task writing the serialized content
return Task.Factory.StartNew(() =>
{
using (var jsonTextWriter = new JsonTextWriter(new StreamWriter(writeStream, Encoding)) { CloseOutput = false })
{
if (isJsonp)
{
jsonTextWriter.WriteRaw(JsonpCallbackFunction + "(");
jsonTextWriter.Flush();
}
serializer.Serialize(jsonTextWriter, value);
jsonTextWriter.Flush();
if (isJsonp)
{
jsonTextWriter.WriteRaw(")");
jsonTextWriter.Flush();
}
}
});
}
}
然后，在你的global.asax.cs中添加这个小美女：
private static void AddJsonFormatterAndSetDefault()
{
var serializerSettings = new JsonSerializerSettings();
serializerSettings.Converters.Add(new IsoDateTimeConverter());
var jsonFormatter = new JsonNetFormatter(serializerSettings);
jsonFormatter.SupportedMediaTypes.Add(new MediaTypeHeaderValue("text/html"));
GlobalConfiguration.Configuration.Formatters.Insert(0, jsonFormatter);
}
从Application_Start
调用它这适用于我支持json和jsonp。