HTTP Status Code大全
HTTP status code
前言：注意这里的status code大部分是ietf统一的，但是也有草案（draft）和服务器（nginx，IIS）相关，还有和服务器供应商（Twitter、Microsoft）有关。
但总体来说，这些统一的status code归ietf维护的是不会有错的
wiki见这里：http://en.wikipedia.org/wiki/List_of_HTTP_status_codes
这里有个检测http response code的网站，大家可以看下。http://savanttools.com/test-http-status-codes
1XX：Informational
这个是服务器端返回值，如果你不是做服务器开发，估计你根本看不到这些值。这些值得含义和作用已经在Server和Client端实现，我们看到是的结果，这个1XX状态码是中间状态。
100:Client should continue with request Explanation：Server已经收到client的request headers，Client应该继续发送request body，如典型的POST请求，中间POST Header发送之后的响应对我们来说是透明的。 101:Server is switching protocols Explanation：This means the requester has asked the server to switch protocols and the server is acknowledging that it will do so 102:Server has received and is processing the request （WebDAV rfc2518） Explanation：As a WebDAV request may contain many sub-requests involving file operations, it may take a long time to complete the request. This code indicates that the server has received and is processing the request, but no response is available yet.[3] This prevents the client from timing out and assuming the request was lost. 最后一句比较关键。 103:resume aborted PUT or POST requests Explanation：This code is used in the Resumable HTTP Requests Proposal to resume aborted PUT or POST requests 122:URI is longer than a maximum of 2083 characters Explanation：This is a non-standard IE7-only code which means the URI is longer than a maximum of 2083 characters
2XX：Success
2XX的状态表示服务器响应返回OK，只是返回给client的状态和内容不一样来区分。你只要看到2XX的响应就明白你发出的请求服务器已经正确响应了。
200:standard response for successful HTTP requests Explanation：Standard response for successful HTTP requests，这个最为常见，不多做解释。 201:request has been fulfilled; new resource created Explanation：The request has been fulfilled and resulted in a new resource being created 202:request accepted, processing pending Explanation：The request has been accepted for processing, but the processing has not been completed. The request might or might not eventually be acted upon, as it might be disallowed when processing actually takes place 203:request processed, information may be from another source HTTP/1.1支持 Explanation：The server successfully processed the request, but is returning information that may be from another source 204:request processed, no content returned Explanation：The server successfully processed the request, but is not returning any content 205:request processed, no content returned, reset document view Explanation：The server successfully processed the request, but is not returning any content. Unlike a 204 response, this response requires that the requester reset the document view 206:partial resource return due to request header Explanation：The server is delivering only part of the resource due to a range header sent by the client. The range header is used by tools like wget to enable resuming of interrupted downloads, or split a download into multiple simultaneous streams 207:XMLl, can contain multiple separate responses Explanation：The message body that follows is an XML message and can contain a number of separate response codes, depending on how many sub-requests were made 208:results previously returned Explanation：The members of a DAV binding have already been enumerated in a previous reply to this request, and are not being included again 226:request fulfilled, reponse is instance-manipulations Explanation：The server has fulfilled a GET request for the resource, and the response is a representation of the result of one or more instance-manipulations applied to the current instance
3XX：Redirection
这个是Server端的Redirection操作，有服务器内部跳转的，也有支持客户端重新跳转的，当然也包括资源的跳转。
300:multiple options for the resource delivered Indicates multiple options for the resource that the client may follow. It, for instance, could be used to present different format options for video, list files with different extensions, or word sense disambiguation 301:this and all future requests directed to the given URI This and all future requests should be directed to the given URI 302:response to request found via alternative URI This is an example of industrial practice contradicting the standard. HTTP/1.0 specification (RFC 1945) required the client to perform a temporary redirect (the original describing phrase was "Moved Temporarily"), but popular browsers implemented 302 with the functionality of a 303 See Other. Therefore, HTTP/1.1 added status codes 303 and 307 to distinguish between the two behaviours. However, some Web applications and frameworks use the 302 status code as if it were the 303 303:response to request found via alternative URI The response to the request can be found under another URI using a GET method. When received in response to a POST (or PUT/DELETE), it should be assumed that the server has received the data and the redirect should be issued with a separate GET message 304:resource has not been modified since last requested Indicates the resource has not been modified since last requested. Typically, the HTTP client provides a header like the If-Modified-Since header to provide a time against which to compare. Using this saves bandwidth and reprocessing on both the server and client, as only the header data must be sent and received in comparison to the entirety of the page being re-processed by the server, then sent again using more bandwidth of the server and client 305:content located elsewhere, retrieve from there Many HTTP clients (such as Mozilla and Internet Explorer) do not correctly handle responses with this status code, primarily for security reasons 306:subsequent requests should use the specified proxy No longer used. Originally meant "Subsequent requests should use the specified proxy 307:connect again to different uri as provided In this occasion, the request should be repeated with another URI, but future requests can still use the original URI. In contrast to 303, the request method should not be changed when reissuing the original request. For instance, a POST request must be repeated using another POST request 308:resumable HTTP Requests This code is used in the Resumable HTTP Requests Proposal to resume aborted PUT or POST requests
4XX：Client Error
4XX的响应一般是指Client的请求URL有问题，有可能是语法、资源路径、路径无法支持或者定位；这种4XX错误一般应该检查路径的正确性，我们最熟悉的就是404了。
400：request cannot be fulfilled due to bad syntax The request cannot be fulfilled due to bad syntax 401：authentication is possible but has failed Similar to 403 Forbidden, but specifically for use when authentication is possible but has failed or not yet been provided. The response must include a WWW-Authenticate header field containing a challenge applicable to the requested resource. See Basic access authentication and Digest access authentication 402：payment required, reserved for future use Reserved for future use. 403：server refuses to respond to request The request was a legal request, but the server is refusing to respond to it. Unlike a 401 Unauthorized response, authenticating will make no difference 404：requested resource could not be found The requested resource could not be found but may be available again in the future. Subsequent requests by the client are permissible 405：request method not supported by that resource A request was made of a resource using a request method not supported by that resource; for example, using GET on a form which requires data to be presented via POST, or using PUT on a read-only resource 406：content not acceptable according to the Accept headers The requested resource is only capable of generating content not acceptable according to the Accept headers sent in the request 407：client must first authenticate itself with the proxy The client must first authenticate itself with the proxy 408：server timed out waiting for the request The server timed out waiting for the request. According to W3 HTTP specifications: "The client did not produce a request within the time that the server was prepared to wait. The client MAY repeat the request without modifications at any later time 409：request could not be processed because of conflict Indicates that the request could not be processed because of conflict in the request, such as an edit conflict 410；resource is no longer available and will not be available again Indicates that the resource requested is no longer available and will not be available again. This should be used when a resource has been intentionally removed and the resource should be purged. Upon receiving a 410 status code, the client should not request the resource again in the future. Clients such as search engines should remove the resource from their indices. Most use cases do not require clients and search engines to purge the resource, and a "404 Not Found" may be used instead 411：request did not specify the length of its content The request did not specify the length of its content, which is required by the requested resource 412：server does not meet request preconditions The server does not meet one of the preconditions that the requester put on the request 413：request is larger than the server is willing or able to process The request is larger than the server is willing or able to process 414：URI provided was too long for the server to process The URI provided was too long for the server to process 415：server does not support media type The request entity has a media type which the server or resource does not support. For example, the client uploads an image as image/svg+xml, but the server requires that images use a different format 416：client has asked for unprovidable portion of the file The client has asked for a portion of the file, but the server cannot supply that portion. For example, if the client asked for a part of the file that lies beyond the end of the file 417：server cannot meet requirements of Expect request-header field The server cannot meet the requirements of the Expect request-header field 418：I'm a teapot This code was defined in 1998 as one of the traditional IETF April Fools' jokes, in RFC 2324, Hyper Text Coffee Pot Control Protocol, and is not expected to be implemented by actual HTTP servers. However, known implementations do exist. An Nginx HTTP server uses this code to simulate goto-like behaviour in its configuration 420：Twitter rate limiting Returned by the Twitter Search and Trends API when the client is being rate limited 422：request unable to be followed due to semantic errors （WebDAV） The request was well-formed but was unable to be followed due to semantic errors 423：resource that is being accessed is locked The resource that is being accessed is locked 424：request failed due to failure of a previous request The request failed due to failure of a previous request (e.g. a PROPPATCH). 426：client should switch to a different protocol The client should switch to a different protocol such as TLS/1.0. 428：origin server requires the request to be conditional The origin server requires the request to be conditional. Intended to prevent "the 'lost update' problem, where a client GETs a resource's state, modifies it, and PUTs it back to the server, when meanwhile a third party has modified the state on the server, leading to a conflict." Proposed in an Internet-Draft 429：user has sent too many requests in a given amount of time The user has sent too many requests in a given amount of time. Intended for use with rate limiting schemes. Proposed in an Internet-Draft 431：server is unwilling to process the request The server is unwilling to process the request because either an individual header field, or all the header fields collectively, are too large. Proposed in an Internet-Draft 444：server returns no information and closes the connection An nginx HTTP server extension. The server returns no information to the client and closes the connection (useful as a deterrent for malware). 449：request should be retried after performing action A Microsoft extension. The request should be retried after performing the appropriate action 450：Windows Parental Controls blocking access to webpage A Microsoft extension. This error is given when Windows Parental Controls are turned on and are blocking access to the given webpage 451：The server cannot reach the client's mailbox. If the client is attempting to connect to the wrong server (that is, a server that cannot access the user's mailbox), or if there is a more efficient server to use to reach the user's mailbox, then a 451 Redirect error is returned 499：connection closed by client while HTTP server is processing An Nginx HTTP server extension. This code is introduced to log the case when the connection is closed by client while HTTP server is processing its request, making server unable to send the HTTP header back
5XX：Server Error
5XX是指服务器错误，有可能是Server暂时无法提供服务、或者Server挂掉了，或者Server不支持连接的协议，也有可能是代理的原因。最熟悉的就是503了。
500：generic error message A generic error message, given when no more specific message is suitable 501：server does not recognise method or lacks ability to fulfill The server either does not recognise the request method, or it lacks the ability to fulfill the request 502：server received an invalid response from upstream server The server was acting as a gateway or proxy and received an invalid response from the upstream server 503：server is currently unavailable The server is currently unavailable (because it is overloaded or down for maintenance).[2] Generally, this is a temporary state 504：gateway did not receive response from upstream server The server was acting as a gateway or proxy and did not receive a timely response from the upstream server 505：server does not support the HTTP protocol version The server does not support the HTTP protocol version used in the request 506：content negotiation for the request results in a circular Transparent content negotiation for the request results in a circular reference 507：server is unable to store the representation The server is unable to store the representation needed to complete the request 508：server detected an infinite loop while processing the request The server detected an infinite loop while processing the request (sent in lieu of 208). 509：bandwidth limit exceeded This status code, while used by many servers, is not specified in any RFCs 510：further extensions to the request are required Further extensions to the request are required for the server to fulfill it 511：client needs to authenticate to gain network access The client needs to authenticate to gain network access. Intended for use by intercepting proxies used to control access to the network (e.g. "captive portals" used to require agreement to Terms of Service before granting full Internet access via a Wi-Fi hotspot). Proposed in an Internet-Draft 598：network read timeout behind the proxy This status code is not specified in any RFCs, but is used by some HTTP proxies to signal a network read timeout behind the proxy to a client in front of the proxy 599：network connect timeout behind the proxy This status code is not specified in any RFCs, but is used by some HTTP proxies to signal a network connect timeout behind the proxy to a client in front of the proxy
这个算是最全的HTTP status code了，好吧，我承认这个最全有哗众取宠的含义。不过如果你遇到的HTTP返回码在这里面没有的话，麻烦告诉我，我给添加上去。
其实HTTP返回码的含义比较容易理解，遇到之后看到服务器的返回就明白什么意思了，不过如果你还想了解返回码的含义及其详细信息，上面这些内容就是一个参考；如果你想进一步了解，ietf官网会是你最好的去处。