如果您使用IIS，我建议尝试IIS CORS模块。 它易于配置，适用于所有类型的控制器。

下面是一个配置示例:

    <system.webServer>
        <cors enabled="true" failUnlistedOrigins="true">
            <add origin="*" />
            <add origin="https://*.microsoft.com"
                 allowCredentials="true"
                 maxAge="120"> 
                <allowHeaders allowAllRequestedHeaders="true">
                    <add header="header1" />
                    <add header="header2" />
                </allowHeaders>
                <allowMethods>
                     <add method="DELETE" />
                </allowMethods>
                <exposeHeaders>
                    <add header="header1" />
                    <add header="header2" />
                </exposeHeaders>
            </add>
            <add origin="http://*" allowed="false" />
        </cors>
    </system.webServer>

After struggling for a whole evening I finally got this to work. After some debugging I found the problem I was walking into was that my client was sending a so called preflight Options request to check if the application was allowed to send a post request with the origin, methods and headers provided. I didn't want to use Owin or an APIController, so I started digging and came up with the following solution with just an ActionFilterAttribute. Especially the "Access-Control-Allow-Headers" part is very important, as the headers mentioned there do have to match the headers your request will send.

using System.Linq;
using System.Web;
using System.Web.Mvc;

namespace MyNamespace
{
    public class AllowCrossSiteJsonAttribute : ActionFilterAttribute
    {
        public override void OnActionExecuting(ActionExecutingContext filterContext)
        {
            HttpRequest request = HttpContext.Current.Request;
            HttpResponse response = HttpContext.Current.Response;

            // check for preflight request
            if (request.Headers.AllKeys.Contains("Origin") && request.HttpMethod == "OPTIONS")
            {
                response.AppendHeader("Access-Control-Allow-Origin", "*");
                response.AppendHeader("Access-Control-Allow-Credentials", "true");
                response.AppendHeader("Access-Control-Allow-Methods", "GET, PUT, POST, DELETE");
                response.AppendHeader("Access-Control-Allow-Headers", "Origin, X-Requested-With, X-RequestDigest, Cache-Control, Content-Type, Accept, Access-Control-Allow-Origin, Session, odata-version");
                response.End();
            }
            else
            {
                HttpContext.Current.Response.Cache.SetCacheability(HttpCacheability.NoCache);
                HttpContext.Current.Response.Cache.SetNoStore();

                response.AppendHeader("Access-Control-Allow-Origin", "*");
                response.AppendHeader("Access-Control-Allow-Credentials", "true");
                if (request.HttpMethod == "POST")
                {
                    response.AppendHeader("Access-Control-Allow-Methods", "GET, PUT, POST, DELETE");
                    response.AppendHeader("Access-Control-Allow-Headers", "Origin, X-Requested-With, X-RequestDigest, Cache-Control, Content-Type, Accept, Access-Control-Allow-Origin, Session, odata-version");
                }

                base.OnActionExecuting(filterContext);
            }
        }
    }
}

最后，我的MVC动作方法看起来像这样。这里重要的是还要提到Options HttpVerbs，否则preflight请求将失败。

[AcceptVerbs(HttpVerbs.Post | HttpVerbs.Options)]
[AllowCrossSiteJson]
public async Task<ActionResult> Create(MyModel model)
{
    return Json(await DoSomething(model));
}

对于普通ASP。NET MVC控制器

创建一个新属性

public class AllowCrossSiteJsonAttribute : ActionFilterAttribute
{
    public override void OnActionExecuting(ActionExecutingContext filterContext)
    {
        filterContext.RequestContext.HttpContext.Response.AddHeader("Access-Control-Allow-Origin", "*");
        base.OnActionExecuting(filterContext);
    }
}

标记你的行动:

[AllowCrossSiteJson]
public ActionResult YourMethod()
{
    return Json("Works better?");
}

ASP。NET Web API

using System;
using System.Web.Http.Filters;

public class AllowCrossSiteJsonAttribute : ActionFilterAttribute
{
    public override void OnActionExecuted(HttpActionExecutedContext actionExecutedContext)
    {
        if (actionExecutedContext.Response != null)
            actionExecutedContext.Response.Headers.Add("Access-Control-Allow-Origin", "*");

        base.OnActionExecuted(actionExecutedContext);
    }
}

标记整个API控制器:

[AllowCrossSiteJson]
public class ValuesController : ApiController
{

或者单独的API调用:

[AllowCrossSiteJson]
public IEnumerable<PartViewModel> Get()
{
    ...
}

对于Internet Explorer <= v9

IE <= 9不支持CORS。我已经写了一个javascript，将自动路由这些请求通过代理。这一切都是100%透明的(你只需要包括我的代理和脚本)。

使用nuget corsproxy下载它，并遵循附带的说明。

博客文章|源代码

如果您正在使用IIS 7+，您可以放置一个web。配置文件到根文件夹与此在系统中。网络服务器:

<httpProtocol>
   <customHeaders>
      <clear />
      <add name="Access-Control-Allow-Origin" value="*" />
   </customHeaders>
</httpProtocol>

参见:http://msdn.microsoft.com/en-us/library/ms178685.aspx 和http://enable-cors.org/ # how-iis7

如果您正在使用API，请将这一行添加到您的方法中。

HttpContext.Current.Response.AddHeader("Access-Control-Allow-Origin", "*"); 

WebAPI 2现在有一个CORS包，可以使用以下方法安装: 安装- package Microsoft.AspNet.WebApi.Cors -pre -project webservice

安装完成后，代码如下所示:http://www.asp.net/web-api/overview/security/enabling-cross-origin-requests-in-web-api