Warning
Warning一般 HTTP 标头包含有关该消息的状态可能出现的问题的信息。Warning响应中可能会出现多个标题。
Warning 标题字段通常可以应用于任何消息，但某些警告代码是特定于高速缓存的，只能应用于响应消息。
Header type | General header |
|---|---|
Forbidden header name | no |
句法
Warning: <warn-code> <warn-agent> <warn-text> [<warn-date>]
指令
<警告码>一个三位警告号码。第一位数字表示是否Warning需要在验证后从存储的响应中删除。
1xx警告代码描述响应的新鲜度或验证状态，并在删除后由缓存删除。
2xx警告代码描述了未通过验证纠正的表示的某些方面，并且验证后不会被缓存删除，除非发送完整的响应。
<warn-agent>
添加Warning标题的服务器或软件的名称或假名（代理未知时可能为“ - ”）。
<warn-text> 描述错误的建议文本 <warn-date> 可选。如果Warning发送多个标题，请包含与Date标题匹配的日期。
警告代码
iana.org 上的 HTTP 警告代码注册表定义了警告代码的命名空间。
Code | Text | Description |
|---|---|---|
110 | Response is Stale | A response provided by a cache is stale (the expiration time set for it has passed). |
111 | Revalidation Failed | An attempt to validate the response failed, due to an inability to reach the server. |
112 | Disconnected Operation | The cache is disconnected from the rest of the network. |
113 | Heuristic Expiration | Sent If a cache heuristically chose a freshness lifetime greater than 24 hours and the response's age is greater than 24 hours. |
199 | Miscellaneous Warning | Arbitrary, non-specific warning |
214 | Transformation Applied | Added by a proxy if it applies any transformation to the representation, such as changing the content-coding, media-type or the like. |
299 | Miscellaneous Warning | Same as 199, but indicating a persistent warning |
例子
Warning: 110 anderson/1.3.37 "Response is stale"Date: Wed, 21 Oct 2015 07:28:00 GMT Warning: 112 - "cache down" "Wed, 21 Oct 2015 07:28:00 GMT"
产品规格
Specification | Title |
|---|---|
RFC 7234, section 5.5: Warning | Hypertext Transfer Protocol (HTTP/1.1): Caching |
浏览器兼容性
Feature | Chrome | Edge | Firefox | Internet Explorer | Opera | Safari |
|---|---|---|---|---|---|---|
Basic Support | (Yes) | (Yes) | (Yes) | (Yes) | (Yes) | (Yes) |
Feature | Android | Chrome for Android | Edge mobile | Firefox for Android | IE mobile | Opera Android | iOS Safari |
|---|---|---|---|---|---|---|---|
Basic Support | (Yes) | (Yes) | (Yes) | (Yes) | (Yes) | (Yes) | (Yes) |