Bri*_*ord 136 jquery jsonp asp.net-mvc-4 asp.net-web-api
我正在使用Web API在ASP.MVC MVC 4中创建一组新服务.到目前为止,这很棒.我已经创建了该服务并使其工作,现在我正在尝试使用JQuery来使用它.我可以使用Fiddler取回JSON字符串,它似乎没问题,但是因为该服务存在于一个单独的站点上,所以尝试使用"不允许"的JQuery错误调用它.所以,这显然是我需要使用JSONP的情况.
我知道Web API是新的,但我希望有人可以帮助我.
如何使用JSONP调用Web API方法？
Bri*_*ord 131
在提出这个问题之后,我终于找到了我需要的东西,所以我正在回答它.
我遇到了这个JsonpMediaTypeFormatter.Application_Start通过执行以下操作将其添加到global.asax中:
var config = GlobalConfiguration.Configuration;
config.Formatters.Insert(0, new JsonpMediaTypeFormatter());
你很高兴看到这样的JQuery AJAX调用:
$.ajax({
url: 'http://myurl.com',
type: 'GET',
dataType: 'jsonp',
success: function (data) {
alert(data.MyProperty);
}
})
它似乎工作得很好.
Pet*_*erg 52
以下是与WebAPI RC一起使用的JsonpMediaTypeFormatter的更新版本:
public class JsonpMediaTypeFormatter : JsonMediaTypeFormatter
{
private string callbackQueryParameter;
public JsonpMediaTypeFormatter()
{
SupportedMediaTypes.Add(DefaultMediaType);
SupportedMediaTypes.Add(new MediaTypeHeaderValue("text/javascript"));
MediaTypeMappings.Add(new UriPathExtensionMapping("jsonp", DefaultMediaType));
}
public string CallbackQueryParameter
{
get { return callbackQueryParameter ?? "callback"; }
set { callbackQueryParameter = value; }
}
public override Task WriteToStreamAsync(Type type, object value, Stream stream, HttpContent content, TransportContext transportContext)
{
string callback;
if (IsJsonpRequest(out callback))
{
return Task.Factory.StartNew(() =>
{
var writer = new StreamWriter(stream);
writer.Write(callback + "(");
writer.Flush();
base.WriteToStreamAsync(type, value, stream, content, transportContext).Wait();
writer.Write(")");
writer.Flush();
});
}
else
{
return base.WriteToStreamAsync(type, value, stream, content, transportContext);
}
}
private bool IsJsonpRequest(out string callback)
{
callback = null;
if (HttpContext.Current.Request.HttpMethod != "GET")
return false;
callback = HttpContext.Current.Request.QueryString[CallbackQueryParameter];
return !string.IsNullOrEmpty(callback);
}
}
小智 21
您可以像这样使用ActionFilterAttribute:
public class JsonCallbackAttribute : ActionFilterAttribute
{
private const string CallbackQueryParameter = "callback";
public override void OnActionExecuted(HttpActionExecutedContext context)
{
var callback = string.Empty;
if (IsJsonp(out callback))
{
var jsonBuilder = new StringBuilder(callback);
jsonBuilder.AppendFormat("({0})", context.Response.Content.ReadAsStringAsync().Result);
context.Response.Content = new StringContent(jsonBuilder.ToString());
}
base.OnActionExecuted(context);
}
private bool IsJsonp(out string callback)
{
callback = HttpContext.Current.Request.QueryString[CallbackQueryParameter];
return !string.IsNullOrEmpty(callback);
}
}
然后把它放在你的行动上:
[JsonCallback]
public IEnumerable<User> User()
{
return _user;
}
Jus*_*tin 11
当然Brian的答案是正确的,但如果您已经使用了Json.Net格式化程序,它为您提供了相当快的json日期和更快的序列化,那么您不能只为jsonp添加第二个格式化程序,您必须将两者结合起来.无论如何最好使用它,正如Scott Hanselman所说,ASP.NET Web API的发布默认会使用Json.Net序列化程序.
public class JsonNetFormatter : MediaTypeFormatter
{
private 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"));
Encoding = new UTF8Encoding(false, true);
//we also support jsonp.
SupportedMediaTypes.Add(new MediaTypeHeaderValue("text/javascript"));
MediaTypeMappings.Add(new UriPathExtensionMapping("jsonp", "application/json"));
}
public string CallbackQueryParameter
{
get { return callbackQueryParameter ?? "jsoncallback"; }
set { callbackQueryParameter = value; }
}
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)
{
string callback;
var isJsonp = IsJsonpRequest(formatterContext.Response.RequestMessage, out callback);
// Create a serializer
JsonSerializer serializer = JsonSerializer.Create(_jsonSerializerSettings);
// Create task writing the serialized content
return Task.Factory.StartNew(() =>
{
using (JsonTextWriter jsonTextWriter = new JsonTextWriter(new StreamWriter(stream, Encoding)) { CloseOutput = false })
{
if (isJsonp)
{
jsonTextWriter.WriteRaw(callback + "(");
jsonTextWriter.Flush();
}
serializer.Serialize(jsonTextWriter, value);
jsonTextWriter.Flush();
if (isJsonp)
{
jsonTextWriter.WriteRaw(")");
jsonTextWriter.Flush();
}
}
});
}
private bool IsJsonpRequest(HttpRequestMessage request, out string callback)
{
callback = null;
if (request.Method != HttpMethod.Get)
return false;
var query = HttpUtility.ParseQueryString(request.RequestUri.Query);
callback = query[CallbackQueryParameter];
return !string.IsNullOrEmpty(callback);
}
}
小智 5
更新
public class JsonpMediaTypeFormatter : JsonMediaTypeFormatter
{
private string callbackQueryParameter;
public JsonpMediaTypeFormatter()
{
SupportedMediaTypes.Add(DefaultMediaType);
SupportedMediaTypes.Add(new MediaTypeHeaderValue("text/javascript"));
MediaTypeMappings.Add(new UriPathExtensionMapping("jsonp", DefaultMediaType));
}
public string CallbackQueryParameter
{
get { return callbackQueryParameter ?? "callback"; }
set { callbackQueryParameter = value; }
}
public override Task WriteToStreamAsync(Type type, object value, Stream writeStream, HttpContent content, 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();
});
}
else
{
return base.WriteToStreamAsync(type, value, writeStream, content, transportContext);
}
}
private bool IsJsonpRequest(out string callback)
{
callback = null;
if (HttpContext.Current.Request.HttpMethod != "GET")
return false;
callback = HttpContext.Current.Request.QueryString[CallbackQueryParameter];
return !string.IsNullOrEmpty(callback);
}
}
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