HTTP头的Expires与Cache-control
1.概念 Cache-control 用于控制HTTP缓存(在HTTP/1.0中可能部分没实现,仅仅实现了Pragma: no-cache) 数据包中的格式: Cache-Control: cache-directive cache-directive可以为以下: request时用到: | "no-cache" | "no-store" | "max-age" "=" delta-seconds | "max-stale" [ "=" delta-seconds ] | "min-fresh" "=" delta-seconds | "no-transform" | "only-if-cached" | "cache-extension" response时用到: | "public" | "private" [ "=" <"> field-name <"> ] | "no-cache" [ "=" <"> field-name <"> ] | "no-store" | "no-transform" | "must-revalidate" | "proxy-revalidate" | "max-age" "=" delta-seconds | "s-maxage" "=" delta-seconds | "cache-extension" 部分说明: 根据是否可缓存分为