Failed to load http://localhost:8090/order/createorder: No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'null' is therefore not allowed access. The response had HTTP status code 404.

浏览器报错是跨域问题，可我OrderController和getItem.html两边都设置了跨域的那句代码，这是怎么回事？和jquery版本有关系吗,我用的是3.3.1