angularjs – CORS标题“Access-Control-Allow-Headers”中的缺省令牌“access-control-allow-headers”来自CORS预检通道

我有两个VS项目：一个暴露MVC5控制器,另一个是角度客户端.我希望角度客户端能够查询控制器.
我读了很多线程,尝试了以下内容：

>我在服务器的web配置中添加了这个：

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

>我创建并使用以下过滤器对控制器的操作：

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

>在角度客户端中,我创建了以下拦截器：

app.factory("CORSInterceptor",[
    function()
    {
        return {
            request: function(config)
            {
                 config.headers["Access-Control-Allow-Origin"] = "*";
                 config.headers["Access-Control-Allow-Methods"] = "GET,POST,OPTIONS";
                 config.headers["Access-Control-Allow-Headers"] = "Content-Type";
                 config.headers["Access-Control-Request-Headers"] = "X-Requested-With,accept,content-type";
                 return config;
            }
     };
}
]);

app.config(["$httpProvider",function ($httpProvider) {
    $httpProvider.interceptors.push("CORSInterceptor");
}]);

据Firebug说,这样做有以下的要求：

OPTIONS //Login/Connect HTTP/1.1
Host: localhost:49815
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:40.0) Gecko/20100101 Firefox/40.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip,deflate
Origin: http://localhost:50739
Access-Control-Request-Method: POST
Access-Control-Request-Headers: access-control-allow-headers,access-control-allow-origin,content-type
Connection: keep-alive
Pragma: no-cache
Cache-Control: no-cache

并有以下回应：

HTTP/1.1 200 OK
Allow: OPTIONS,TRACE,GET,HEAD,POST
Server: Microsoft-IIS/10.0
Public: OPTIONS,POST
X-SourceFiles: =?UTF-8?B?RDpcVEZTXElVV2vixEdhcE5ldFNlcnZlclxBU1BTZXJ2aWNlc1xMb2dpblxDb25uZWN0?=
Access-Control-Allow-Origin: *
Access-Control-Allow-Methods: GET,OPTIONS
Access-Control-Allow-Headers: *
Access-Control-Request-Headers: X-Requested-With,content-type
Date: Tue,01 Sep 2015 13:05:23 GMT
Content-Length: 0

而且,Firefox仍然会使用以下消息阻止该请求：

Cross-Origin Request Blocked: The Same Origin Policy disallows reading the remote resource at http://localhost:49815//Login/Connect. (Reason: missing token 'access-control-allow-headers' in CORS header 'Access-Control-Allow-Headers' from CORS preflight channel).

通常,我读到的线程提示了几个不必要的配置步骤,造成混乱.其实很简单

为了发送跨站点请求,从角度客户端到ASP控制器的简单目的：

>不需要角度拦截器.
>服务器端不需要自定义过滤器.
>唯一的强制修改是将它添加到服务器的web.config中

<system.webServer>
      <httpProtocol>
          <customHeaders>
              <clear />
              <add name="Access-Control-Allow-Origin" value="*" />
              <add name="Access-Control-Allow-Headers" value="Content-Type"/>
          </customHeaders>
     </httpProtocol>
</system.webServer>