ASP.net MVC返回JSONP

Question

我希望跨域返回一些JSON,我知道这样做的方法是通过JSONP而不是纯JSON.我正在使用ASP.net MVC所以我正在考虑只是扩展JSONResult类型然后extendig Controller,以便它还实现了一个Jsonp方法.这是最好的解决方法,还是内置的ActionResult可能会更好？

编辑:我继续前进并做到了.仅供参考,我添加了一个新结果:

public class JsonpResult : System.Web.Mvc.JsonResult
    {
        public override void ExecuteResult(ControllerContext context)
        {
            if (context == null)
            {
                throw new ArgumentNullException("context");
            }

            HttpResponseBase response = context.HttpContext.Response;

            if (!String.IsNullOrEmpty(ContentType))
            {
                response.ContentType = ContentType;
            }
            else
            {
                response.ContentType = "application/javascript";
            }
            if (ContentEncoding != null)
            {
                response.ContentEncoding = ContentEncoding;
            }
            if (Data != null)
            {
                // The JavaScriptSerializer type was marked as obsolete prior to .NET Framework 3.5 SP1
#pragma warning disable 0618
                HttpRequestBase request = context.HttpContext.Request;

                JavaScriptSerializer serializer = new JavaScriptSerializer();
                response.Write(request.Params["jsoncallback"] + "(" + serializer.Serialize(Data) + ")");
#pragma warning restore 0618
            }
        }
    }

以及我所有控制器的超类的几种方法:

protected internal JsonpResult Jsonp(object data)
        {
            return Jsonp(data, null /* contentType */);
        }

        protected internal JsonpResult Jsonp(object data, string contentType)
        {
            return Jsonp(data, contentType, null);
        }

        protected internal virtual JsonpResult Jsonp(object data, string contentType, Encoding contentEncoding)
        {
            return new JsonpResult
            {
                Data = data,
                ContentType = contentType,
                ContentEncoding = contentEncoding
            };
        }

奇迹般有效.

Answer 1

如果您不想定义动作过滤器,这是一个简单的解决方案

使用jQuery的客户端代码:

  $.ajax("http://www.myserver.com/Home/JsonpCall", { dataType: "jsonp" }).done(function (result) {});

MVC控制器动作.返回内容结果,JavaScript代码执行随查询字符串提供的回调函数.还为响应设置JavaScript MIME类型.

 public ContentResult JsonpCall(string callback)
 {
      return Content(String.Format("{0}({1});",
          callback, 
          new JavaScriptSerializer().Serialize(new { a = 1 })),    
          "application/javascript");
 }

Answer 2

我没有使用Jsonp()方法对我的控制器进行子类化,而是使用了扩展方法路径,因为它让我感觉更干净.关于JsonpResult的好处是你可以像测试JsonResult一样测试它.

我做了:

public static class JsonResultExtensions
{
    public static JsonpResult ToJsonp(this JsonResult json)
    {
        return new JsonpResult { ContentEncoding = json.ContentEncoding, ContentType = json.ContentType, Data = json.Data, JsonRequestBehavior = json.JsonRequestBehavior};
    }
}

这样您就不必担心创建所有不同的Jsonp()重载,只需将JsonResult转换为Jsonp.

Answer 3

Ranju的博客文章(又名"我发现的这篇博文")非常好,阅读它将允许您进一步解决下面的解决方案,以便您的控制器可以在同一控制器操作中优雅地处理同域JSON和跨域JSONP请求附加代码[在行动中].

无论如何,对于"给我代码"类型,这里是,如果博客再次消失.

在您的控制器中(此代码段是新的/非博客代码):

[AllowCrossSiteJson]
public ActionResult JsonpTime(string callback)
{
    string msg = DateTime.UtcNow.ToString("o");
    return new JsonpResult
    {
        Data = (new
        {
            time = msg
        })
    };
}

JsonpResult在这篇优秀的博文中发现 :

/// <summary>
/// Renders result as JSON and also wraps the JSON in a call
/// to the callback function specified in "JsonpResult.Callback".
/// http://blogorama.nerdworks.in/entry-EnablingJSONPcallsonASPNETMVC.aspx
/// </summary>
public class JsonpResult : JsonResult
{
    /// <summary>
    /// Gets or sets the javascript callback function that is
    /// to be invoked in the resulting script output.
    /// </summary>
    /// <value>The callback function name.</value>
    public string Callback { get; set; }

    /// <summary>
    /// Enables processing of the result of an action method by a
    /// custom type that inherits from <see cref="T:System.Web.Mvc.ActionResult"/>.
    /// </summary>
    /// <param name="context">The context within which the
    /// result is executed.</param>
    public override void ExecuteResult(ControllerContext context)
    {
        if (context == null)
            throw new ArgumentNullException("context");

        HttpResponseBase response = context.HttpContext.Response;
        if (!String.IsNullOrEmpty(ContentType))
            response.ContentType = ContentType;
        else
            response.ContentType = "application/javascript";

        if (ContentEncoding != null)
            response.ContentEncoding = ContentEncoding;

        if (Callback == null || Callback.Length == 0)
            Callback = context.HttpContext.Request.QueryString["callback"];

        if (Data != null)
        {
            // The JavaScriptSerializer type was marked as obsolete
            // prior to .NET Framework 3.5 SP1 
#pragma warning disable 0618
            JavaScriptSerializer serializer = new JavaScriptSerializer();
            string ser = serializer.Serialize(Data);
            response.Write(Callback + "(" + ser + ");");
#pragma warning restore 0618
        }
    }
}

注意:跟随@Ranju和其他人对OP的评论,我认为值得将Ranju的博客文章中的"最低限度"功能代码作为社区维基发布.虽然可以说Ranju在他的博客上添加了上述和其他代码以便自由使用,但我不打算在这里复制他的话.