被CORS政策屏蔽怎么办？“对预检请求的响应未通过访问控制检查”

我已经创建了Trip服务器。它工作得很好，我们可以发出Insomnia方面的请求，但当我们在前端发出AXIOS请求时，它则会发送一个错误：

has been blocked by CORS policy: Response to preflight request doesn’t pass access control check: It does not have HTTP ok status.

我们对AXOS的请求：

let config = {
headers: {
  "Content-Type": "application/json",
  'Access-Control-Allow-Origin': '*',
  }
}

let data = {
  "id": 4
 }

 axios.post('http://196.121.147.69:9777/twirp/route.FRoute/GetLists', data, config)
   .then((res) => {
      console.log(res)
     })
    .catch((err) => {
      console.log(err)
   });
} 

我的 Go 文件显示：

func setupResponse(w *http.ResponseWriter, req *http.Request) {
    (*w).Header().Set("Access-Control-Allow-Origin", "*")
    (*w).Header().Set("Access-Control-Allow-Methods", "POST,GET,OPTIONS, PUT, DELETE")

    (*w).Header().Set("Access-Control-Allow-Headers", "Accept, Content-Type, Content-Length, Accept-Encoding, X-CSRF-Token, Authorization")
}


func WithUserAgent(base http.Handler) http.Handler {
    return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {

    ctx := r.Context()
    ua := r.Header.Get("Jwt")
    ctx = context.WithValue(ctx, "jwt", ua)

    r = r.WithContext(ctx)

    setupResponse(&w, r)
     base.ServeHTTP(w, r)
  })
}

const (
    host     = "localhost"
    port     = 5432
    user     = "postgres"
    password = "postgres"
    dbname   = "postgres"
)

func main() {

    psqlInfo := fmt.Sprintf("host=%s port=%d user=%s "+
           "password=%s dbname=%s sslmode=disable",
               host, port, user, password, dbname)

    server := &s.Server{psqlInfo}

    twirpHandler := p.NewFinanceServiceServer(server, nil)

    wrap := WithUserAgent(twirpHandler)
      log.Fatalln(http.ListenAndServe(":9707", wrap))
}

I believe this is the simplest example:

header := w.Header()
header.Add("Access-Control-Allow-Origin", "*")
header.Add("Access-Control-Allow-Methods", "DELETE, POST, GET, OPTIONS")
header.Add("Access-Control-Allow-Headers", "Content-Type, Access-Control-Allow-Headers, Authorization, X-Requested-With")

You can also add a header for Access-Control-Max-Age and of course you can allow any headers and methods that you wish.

Finally you want to respond to the initial request:

if r.Method == "OPTIONS" {
    w.WriteHeader(http.StatusOK)
    return
}

Edit (June 2019): We now use gorilla for this. Their stuff is more actively maintained and they have been doing this for a really long time. Leaving the link to the old one, just in case.

Old Middleware Recommendation below: Of course it would probably be easier to just use middleware for this. I don't think I've used it, but this one seems to come highly recommended.

Enable cross-origin requests in ASP.NET Web API click for more info

Enable CORS in the WebService app. First, add the CORS NuGet package. In Visual Studio, from the Tools menu, select NuGet Package Manager, then select Package Manager Console. In the Package Manager Console window, type the following command:

Install-Package Microsoft.AspNet.WebApi.Cors

This command installs the latest package and updates all dependencies, including the core Web API libraries. Use the -Version flag to target a specific version. The CORS package requires Web API 2.0 or later.

Open the file App_Start/WebApiConfig.cs. Add the following code to the WebApiConfig.Register method:

using System.Web.Http;
namespace WebService
{
    public static class WebApiConfig
    {
        public static void Register(HttpConfiguration config)
        {
            // New code
            config.EnableCors();

            config.Routes.MapHttpRoute(
                name: "DefaultApi",
                routeTemplate: "api/{controller}/{id}",
                defaults: new { id = RouteParameter.Optional }
            );
        }
    }
}

Next, add the [EnableCors] attribute to your controller/ controller methods

using System.Net.Http;
using System.Web.Http;
using System.Web.Http.Cors;

namespace WebService.Controllers
{
    [EnableCors(origins: "http://mywebclient.azurewebsites.net", headers: "*", methods: "*")]
    public class TestController : ApiController
    {
        // Controller methods not shown...
    }
}

Enable Cross-Origin Requests (CORS) in ASP.NET Core

The provided solution here is correct. However, the same error can also occur from a user error, where your endpoint request method is matching the method your using when making the request.

For example, the server endpoint is defined with "RequestMethod.PUT" while you are requesting the method as POST.