.net webapi cors跨域

Question

webapi的接口项目，引用了Microsoft.AspNet.WebApi.Cors进行跨域
WebConfig和WebApiConfig都已经配置了

现在POST的请求没有问题

但是GET的请求，查看返回的请求头，没有任何跨域的标记，导致报跨域错误。

Web.config中的handlers

<handlers>
      <remove name="ExtensionlessUrlHandler-ISAPI-4.0_32bit" />
      <remove name="ExtensionlessUrlHandler-ISAPI-4.0_64bit" />
      <remove name="ExtensionlessUrlHandler-Integrated-4.0" />
      <add name="ExtensionlessUrlHandler-ISAPI-4.0_32bit" path="*." verb="GET,HEAD,POST,DEBUG,PUT,DELETE,PATCH,OPTIONS" modules="IsapiModule" scriptProcessor="%windir%\Microsoft.NET\Framework\v4.0.30319\aspnet_isapi.dll" preCondition="classicMode,runtimeVersionv4.0,bitness32" responseBufferLimit="0" />
      <add name="ExtensionlessUrlHandler-ISAPI-4.0_64bit" path="*." verb="GET,HEAD,POST,DEBUG,PUT,DELETE,PATCH,OPTIONS" modules="IsapiModule" scriptProcessor="%windir%\Microsoft.NET\Framework64\v4.0.30319\aspnet_isapi.dll" preCondition="classicMode,runtimeVersionv4.0,bitness64" responseBufferLimit="0" />
      <add name="ExtensionlessUrlHandler-Integrated-4.0" path="*." verb="GET,HEAD,POST,DEBUG,PUT,DELETE,PATCH,OPTIONS" type="System.Web.Handlers.TransferRequestHandler" preCondition="integratedMode,runtimeVersionv4.0" />
      <remove name="OPTIONSVerbHandler" />
      <remove name="TRACEVerbHandler" />
    </handlers>

WebApiConfig中的配置

 //跨域设置
 config.EnableCors(new System.Web.Http.Cors.EnableCorsAttribute("*", "*", "*"));

POST返回的请求头

HTTP/1.1 200 OK
Cache-Control: no-cache
Pragma: no-cache
Content-Type: application/json; charset=utf-8
Expires: -1
Server: Microsoft-IIS/10.0
Access-Control-Allow-Origin: *
X-AspNet-Version: 4.0.30319
X-Powered-By: ASP.NET
Date: Wed, 17 Apr 2019 15:20:23 GMT
Content-Length: 407

GET返回的请求头

HTTP/1.1 200 OK
Cache-Control: private
Transfer-Encoding: chunked
Content-Type: application/json; charset=utf-8
Server: Microsoft-IIS/10.0
X-AspNet-Version: 4.0.30319
X-Powered-By: ASP.NET
Date: Wed, 17 Apr 2019 15:17:53 GMT

Answer 1

引用错了，通过NUGET 引用Microsoft.Owin.Cors.dll
public partial class Startup
{

    // 有关配置身份验证的详细信息，请访问 https://go.microsoft.com/fwlink/?LinkId=301864
    public void ConfigureAuth(IAppBuilder app)
    {
                    //跨域
        app.UseCors(Microsoft.Owin.Cors.CorsOptions.AllowAll);