服务器获取自定义header

前端请求自定义header后端无法获取：

解决：改成首字母大写用 - 分割，例：Ap-Token: ****************

文档 RFC7504 明确指出Header的定义：

8.1.2.  HTTP Header Fields
 
   HTTP header fields carry information as a series of key-value pairs.
   For a listing of registered HTTP headers, see the "Message Header
   Field" registry maintained at <https://www.iana.org/assignments/
   message-headers>.
 
   Just as in HTTP/1.x, header field names are strings of ASCII
   characters that are compared in a case-insensitive fashion.  However,
   header field names MUST be converted to lowercase prior to their
   encoding in HTTP/2.  A request or response containing uppercase
   header field names MUST be treated as malformed (Section 8.1.2.6).

服务端 Nginx 开启了 HTTP/2，HTTP/2 和 HTTP/1.x 同样使用 ASCII 字符集，但 HTTP/2 头部必须使用小写，而不像 HTTP/1.x 大小写均可。