The initial request has been accepted and the customer should continue to send the rest of the request. (HTTP 1.1 new)
101 Switching Protocols
The server will switch to another protocol in accordance with the client's request (HTTP 1.1 new)
Everything is ok, and the answer to the GET and POST requests is followed.
The server has created the document and the Location header gives its URL.
The request has been accepted, but the processing has not been completed.
203 Non-Authoritative Information
The document has returned normally, but some of the response headers may be incorrect because a copy of the document is used (HTTP 1.1 new).
204 No Content
Without a new document, the browser should continue to display the original document. This status code is useful if the user refreshes the page periodically and the servlet can determine that the user document is new enough.
205 Reset Content
There is no new content, but the browser should reset what it displays. Used to force the browser to clear the form input (HTTP 1.1 new).
206 Partial Content
The client sent a GET request with a Range header and the server completed it (HTTP 1.1 new).
300 Multiple Choices
The documents requested by the customer can be found in multiple locations, which are already listed in the returned document. If the server wants to make a preference, it should be indicated in the Location response header.
301 Moved Permanently
The document requested by the client is elsewhere, the new URL is given in the Location header, and the browser should automatically access the new URL.
Similar to 301, but the new URL should be considered a temporary replacement, not permanent. Note that the corresponding status information in HTTP 1.0 is "Moved Temporatily". When the status code appears, the browser can automatically access the new URL, so it is a useful status code. Note that this status code can sometimes be used in conjunction with 301. For example, if the browser incorrectly requests http://host/~user (the trailing slash is missing), some servers return 301, and some return 302. Strictly speaking, we can only assume that the browser will automatically redirect only when the original request is GET. See 307.
303 See Other
Similar to 301/302, the difference is that if the original request is POST, the redirect target document specified by the Location header should be extracted via GET (HTTP 1.1 new).
304 Not Modified
The client has a buffered document and issues a conditional request (generally an If-Modified-Since header is provided to indicate that the client only wants to update the document than the specified date). The server tells the customer that the originally buffered document can continue to be used.
305 Use Proxy
The document requested by the client should be extracted by the proxy server specified by the Location header (HTTP 1.1 new).
307 Temporary Redirect
Same as 302 (Found). Many browsers will respond incorrectly to the 302 response for redirection, even if the original request is POST, even though it can only be redirected when the response to the POST request is 303. For this reason, HTTP 1.1 adds 307 to more clearly distinguish between several status codes: when a 303 response occurs, the browser can follow the redirected GET and POST requests; if it is a 307 response, the browser can only follow Redirection of GET requests. (HTTP 1.1 new)
400 Bad Request
The request has a syntax error.
The client tried to gain unauthorized access to the password-protected page. The response will contain a WWW-Authenticate header, which will display the User Name/Password dialog box and then issue the request again after filling in the appropriate Authorization header.
Resources are not available. The server understands the client's request but refuses to process it. Usually caused by permission settings for files or directories on the server.
404 Not Found
Unable to find resource for the specified location. This is also a common response.
405 Method Not Allowed
The request method (GET, POST, HEAD, DELETE, PUT, TRACE, etc.) does not apply to the specified resource. (HTTP 1.1 new)
406 Not Acceptable
The specified resource has been found, but its MIME type is not compatible with the client specified in the Accpet header (HTTP 1.1 new).
407 Proxy Authentication Required
Similar to 401, indicating that the client must first be authorized by the proxy server. (HTTP 1.1 new)
408 Request Timeout
The customer has not issued any requests during the waiting time of the server license. Customers can repeat the same request later. (HTTP 1.1 new)
Usually related to PUT requests. The request could not be successful because the request and the current state of the resource conflict. (HTTP 1.1 new)
The requested document is no longer available, and the server does not know which address to redirect to. It differs from 404 in that a return of 407 indicates that the document has permanently left the specified location, and a 404 indicates that the document is not available for unknown reasons. (HTTP 1.1 new)
411 Length Required
The server cannot process the request unless the client sends a Content-Length header. (HTTP 1.1 new)
412 Precondition Failed
Some of the prerequisites specified in the request header failed (HTTP 1.1 new).
413 Request Entity Too Large
The size of the target document exceeds the size that the server is currently willing to process. If the server thinks it can handle the request later, it should provide a Retry-After header (HTTP 1.1 new).
414 Request URI Too Long
The URI is too long (new in HTTP 1.1).
416 Requested Range Not Satisfiable
The server cannot satisfy the Range header specified by the client in the request. (HTTP 1.1 new)
500 Internal Server Error
The server encountered an unexpected situation and could not complete the client's request.
501 Not Implemented
The server does not support the functionality required to implement the request. For example, the client issues a PUT request that is not supported by the server.
502 Bad Gateway
When the server acts as a gateway or proxy, it accesses the next server in order to complete the request, but the server returns an illegal response.
503 Service Unavailable
The server failed to respond due to maintenance or heavy load. For example, a servlet might return 503 if the database connection pool is full. A Retry-After header can be provided when the server returns to 503.
504 Gateway Timeout
Used by a server acting as a proxy or gateway, indicating that a response cannot be obtained from a remote server in a timely manner. (HTTP 1.1 new)
505 HTTP Version Not Supported
The server does not support the HTTP version specified in the request. (HTTP 1.1 new)
The above is a variety of website status codes, I hope everyone can remember!