如何让 Safari 发送 if-modified-since 标头？
当我生成一个页面时
HTTP/1.1 200 OK
Cache-Control: private
Content-Type: text/html; charset=utf-8
Last-Modified: Mon, 04 Apr 2011 20:08:33 GMT
Vary: Accept-Encoding
Date: Mon, 11 Apr 2011 01:36:21 GMT
Content-Length: 3019
，我会发送标头，当我尝试再次获取此页面时，所有浏览器都会发送正确的请求并获得 304 答案，除了 Safari - 它从不发送 if-modified-since。它总是重新加载整个页面，即使它没有被更改
Safari 的这种行为是否已知以及如何使 Safari 以正确的方式工作？
When I generate a page I send headers
HTTP/1.1 200 OK
Cache-Control: private
Content-Type: text/html; charset=utf-8
Last-Modified: Mon, 04 Apr 2011 20:08:33 GMT
Vary: Accept-Encoding
Date: Mon, 11 Apr 2011 01:36:21 GMT
Content-Length: 3019
then, when I try to get this page again all browsers send correct request and get 304 answer except Safari - it never sends if-modified-since. It always reloads whole page even it havnt been changed
Does this behavior of Safari known and what to do to make Safari work in right way?
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Bart Lateur 写了一篇文章 关于这一点，有一段关于 Safari 的说明：
Bart Lateur wrote a post about this, with a paragraph stating about Safari:
我在 Safari 8.0 中遇到了这个问题。尽管向 Safari 提供了 Last-Modified 标头，但它不会在后续请求中提供 If-Modified-Since 标头。我的解决方案是另外将
Expires标头设置为与Last-Modified标头相同的 html-date。以下是成功交换的示例：
初始请求
来自 Safari 的标准首次请求。
初始响应
我将
Expires和Last-Modified标头指定为相同的有效 html-date。我没有尝试过，但我怀疑 Safari 是否会遵守设置为-1的Expires标头。后续请求
最后，Safari 提供了所需的
If-Modified-Since标头。后续响应
我可以满意地返回 304。
I ran into this with Safari 8.0. Despite providing the
Last-Modifiedheader to Safari it would not provide theIf-Modified-Sinceheader on subsequent requests. The fix in my case was to additionally set theExpiresheader to the same html-date as theLast-Modifiedheader.Here's an example of what the successful exchange looks like:
Initial Request
Standard first request from Safari.
Initial Response
I specify both the
ExpiresandLast-Modifiedheaders as the same valid html-date. I have not tried but I doubt Safari will honor anExpiresheader set to-1.Subsequent Request
At last Safari provides the needed
If-Modified-Sinceheader.Subsequent Response
I can satisfyingly return a 304.
Safari 只是部分免费软件。除了屏住呼吸等待 Apple 将整个 Safari 作为免费软件发布之外，作为 Safari 用户，您还可以使用缓存代理并将其配置为违反规范并忽略 Safari 发送的 Cache-Control 标头。
Squid 有 refresh_pattern 指令，我确信其他代理也有类似的功能。
然后，您可以将 Safari 配置为使用代理，或者您可以本着 颠倒互联网。
Safari is only partly free software. Other than holding your breath until Apple releases the whole of Safari as free software, as a Safari user you could use a caching proxy and configure it to break the spec and ignore the Cache-Control headers Safari sends.
Squid has the refresh_pattern directive, and I'm sure other proxies have similar functionality.
You can then configure Safari to use the proxy, or you can do it transparently in the spirit of upside-down-ternet.
在我的测试中，Safari 需要“Expires”或“Cache-Control”标头以及“Last-Modified”标头。
或者，
注意：Safari 需要“max-age”来尊重“Last-Modified”
In my testing, Safari is expecting either an "Expires" or "Cache-Control" header along with "Last-Modified".
Or,
NOTE: "max-age" was required for Safari to honor the "Last-Modified"