HTTP参考手册

状态 | Status

HTTP 428 Precondition Required响应状态码指示服务器要求有条件的请求。

通常，这意味着所需的先决条件头，如If-Match，缺少。

当前提条件头与服务器端状态不匹配时，响应应该是412 Precondition Failed。

428 Precondition Required

规范	标题
RFC 6585，第3节：428先决条件要求	其他HTTP状态码

1.100 Continue
2.101 Switching Protocols
3.200 OK
4.201 Created
5.202 Accepted
6.203 Non-Authoritative Information
7.204 No Content
8.205 Reset Content
9.206 Partial Content
10.300 Multiple Choices
11.301 Moved Permanently
12.302 Found
13.303 See Other
14.304 Not Modified
15.307 Temporary Redirect
16.308 Permanent Redirect
17.400 Bad Request
18.401 Unauthorized
19.403 Forbidden
20.404 Not Found
21.405 Method Not Allowed
22.406 Not Acceptable
23.407 Proxy Authentication Required
24.408 Request Timeout
25.409 Conflict
26.410 Gone
27.411 Length Required
28.412 Precondition Failed
29.413 Payload Too Large
30.414 URI Too Long
31.415 Unsupported Media Type
32.416 Range Not Satisfiable
33.417 Expectation Failed
34.426 Upgrade Required
35.429 Too Many Requests
36.431 Request Header Fields Too Large
37.451 Unavailable For Legal Reasons
38.500 Internal Server Error
39.501 Not Implemented
40.502 Bad Gateway
41.503 Service Unavailable
42.504 Gateway Timeout
43.505 HTTP Version Not Supported
44.511 Network Authentication Required
45.Status

HTTP

超文本传输协议（ HTTP，HyperText Transfer Protocol ) 是互联网上应用最为广泛的一种网络协议。所有的 WWW 文件都必须遵守这个标准。

1.指南 \| Guides
2.指南：基础 \| Guides: Basics
3.CSP
4.标题 \| Headers
5.方法 \| Methods
6.RFC 2616: HTTP/1.1
7.RFC 4918: WebDAV
8.RFC 5023: The Atom Publishing Protocol
9.RFC 7230: Message Syntax and Routing
10.RFC 7231: Semantics and Content
11.RFC 7232: Conditional Requests
12.RFC 7233: Range Requests
13.RFC 7234: Caching
14.RFC 7235: Authentication
15.状态 \| Status
16.HTTP 请求方法
17.HTTP状态码
18.HTTP 响应头信息
19.HTTP 教程