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方法
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常量

HTTP_IF_MODIFIED_SINCE = "HTTP_IF_MODIFIED_SINCE"
 
HTTP_IF_NONE_MATCH = "HTTP_IF_NONE_MATCH"
 

实例公共方法

etag_matches?(etag)

# File actionpack/lib/action_dispatch/http/cache.rb, line 32
def etag_matches?(etag)
  if etag
    validators = if_none_match_etags
    validators.include?(etag) || validators.include?("*")
  end
end

fresh?(response)

检查响应的新鲜度(Last-ModifiedETag)与请求的 If-Modified-SinceIf-None-Match 条件。如果同时提供这两个头信息,则根据配置,优先使用 ETag 或同时考虑这两个头信息。您可以使用 config.action_dispatch.strict_freshness 调整优先级。参考:tools.ietf.org/html/rfc7232#section-6

# File actionpack/lib/action_dispatch/http/cache.rb, line 45
def fresh?(response)
  if Request.strict_freshness
    if if_none_match
      etag_matches?(response.etag)
    elsif if_modified_since
      not_modified?(response.last_modified)
    else
      false
    end
  else
    last_modified = if_modified_since
    etag          = if_none_match

    return false unless last_modified || etag

    success = true
    success &&= not_modified?(response.last_modified) if last_modified
    success &&= etag_matches?(response.etag) if etag
    success
  end
end

if_modified_since()

# File actionpack/lib/action_dispatch/http/cache.rb, line 14
def if_modified_since
  if since = get_header(HTTP_IF_MODIFIED_SINCE)
    Time.rfc2822(since) rescue nil
  end
end

if_none_match()

# File actionpack/lib/action_dispatch/http/cache.rb, line 20
def if_none_match
  get_header HTTP_IF_NONE_MATCH
end

if_none_match_etags()

# File actionpack/lib/action_dispatch/http/cache.rb, line 24
def if_none_match_etags
  if_none_match ? if_none_match.split(",").each(&:strip!) : []
end

not_modified?(modified_at)

# File actionpack/lib/action_dispatch/http/cache.rb, line 28
def not_modified?(modified_at)
  if_modified_since && modified_at && if_modified_since >= modified_at
end