缓存策略问题

[why168]

ETag →0f47f5cd1b7dee9f

Access-Control-Allow-Origin →*
Cache-Control →no-store, no-cache, must-revalidate, post-check=0, pre-check=0
Connection →keep-alive
Content-Type →application/json
Date →Wed, 30 May 2018 09:30:49 GMT
ETag →0f47f5cd1b7dee9f
Expires →Thu, 19 Nov 1981 08:52:00 GMT
Pragma →no-cache
Server →nginx
Transfer-Encoding →chunked

通过对ETag判断是否变化来更新