https://www.cnblogs.com/chenqf/p/6386163.html
1.http缓存:
强制缓存:Cache-Control:public/private/no-cache/no-store/max-age=xxx
Expires过期时间,绝对时间服务器时间有本地时间不一致会导致缓存失效
协商缓存: Etag <----> If-None-Match
Last-modify<----->If-Modify-since
优先级:Cache-Control>Expires>Etag>Last-modify
2.浏览器的缓存:webStorage(localStorage、sessionStorage)
cookie