跨域请求，浏览器提示
Access to XMLHttpRequest at 'xxx1' from origin 'xxx2 has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource.
解决方法为：
添加header
Access-Control-Allow-Origin:
*
跨域请求，浏览器提示
Access to XMLHttpRequest at 'xxx1' from origin 'xxx2 has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource.
解决方法为：
添加header