missing - cors javascript

¿Cómo se configuran los encabezados CORS en las respuestas de error internas del servidor?

Question

Tengo un servidor de aplicaciones Java con una interfaz REST proporcionada por resteasy y tengo el filtro CORS abajo

@Provider
public class CORSFilter implements ContainerResponseFilter {
public void filter(ContainerRequestContext cReq, ContainerResponseContext cResp) {
cResp.getHeaders().add("Access-Control-Allow-Origin", "*");
cResp.getHeaders().add("Access-Control-Allow-Headers", "origin, content-type, accept, authorization, auth-token");
cResp.getHeaders().add("Access-Control-Allow-Credentials", "true");
cResp.getHeaders().add("Access-Control-Allow-Methods", "GET, POST, PUT, DELETE, OPTIONS, HEAD");
cResp.getHeaders().add("Access-Control-Max-Age", "1209600");
}
}

Todas las solicitudes vuelven con los encabezados CORS:

OPTIONS 200 OK
Access-Control-Allow-Credentials:"true"
Access-Control-Allow-Headers:"origin, content-type, accept, authorization, auth-token"
Access-Control-Allow-Methods:"GET, POST, PUT, DELETE, OPTIONS, HEAD"
Access-Control-Allow-Origin:"*"
Access-Control-Max-Age:"1209600"
Allow:"HEAD, GET, OPTIONS"
Connection:"keep-alive"
Content-Length:"18"
Content-Type:"text/plain"
Date:"Thu, 15 Jan 2015 15:23:01 GMT"
Server:"WildFly/8"

excepto cuando tengo una excepción interna que devuelve el código de error 500:

GET 500 Internal Server Error
Connection:"keep-alive"
Content-Length:"8228"
Content-Type:"text/html; charset=UTF-8"
Date:"Thu, 15 Jan 2015 15:23:01 GMT"

¿Cómo puedo hacer que 500 respuestas contengan esos encabezados?

Answer 1

Use un ExceptionMapper :

@Provider
public class CorsExceptionMapper implements ExceptionMapper<Exception> {
@Override
public Response toResponse(Exception ex) {
ResponseBuilder responseBuilder = Response.serverError();
responseBuilder.header("Access-Control-Allow-Origin", "*");
responseBuilder.header("Access-Control-Allow-Headers", "origin, content-type, accept, authorization, auth-token");
responseBuilder.header("Access-Control-Allow-Credentials", "true");
responseBuilder.header("Access-Control-Allow-Methods", "GET, POST, PUT, DELETE, OPTIONS, HEAD");
responseBuilder.header("Access-Control-Max-Age", "1209600");
return responseBuilder.build();
}
}

Para evitar la duplicación de encabezados, debe usar:

cResp.getHeaders().putSingle() 

En el ContainerResponseFilter .