android - IOS UIWebView 和 Safari 不发送 If-None-Match 但 Android WebView 和 Chrome 发送

Question

我使用 ASP.NET 作为 IOS 和 Android 的服务器，它使用 ETag 和 If-None-Match header 返回 304 或 200。当我在 Chrome 开发工具和远程调试 Android WebView 上检查时，一切正常意味着他正在发送 If-None-Match 请求 header 。但是在 Safari 和远程调试 IOS UIWebView 中做同样的事情总是不发送 If-None-Match header 。 If-None-Match header 是否在 IOS 中不起作用。 Safari 中的结果相同

编辑:这是 Safari 中的响应 header ，

Cache-Control:private
Content-Encoding:gzip
Content-Length:448
Content-Type:text/html; charset=utf-8
Date:Wed, 19 Jun 2013 09:27:46 GMT
Etag:00amyWGct0y_ze4lIsj2Mw
Server:Microsoft-IIS/7.5
Vary:Accept-Encoding
X-AspNet-Version:4.0.30319
X-Powered-By:ASP.NET

Answer 1

来自 here ,

Caution A few years ago, ETags were used mostly by proxies and not as much by browsers. The value of ETags slowly grows because of the increasing support by browsers. Keep in mind that not all browsers support ETags, though. For example, Apple's Safari does not support them. You may consider providing Last-Modified headers as well and checking for If-Modified-Since headers in addition to using ETags if you expect a large number of of Safari users to visit your site