HTTP status codes and corresponding strings

HTTP Request Message

L HTTP command: // Method Field, indicating that the get method is used

L URI: // URL field, which sends a request to the server that saves the website.

L HTTP Version: // HTTP Protocol version field, which is HTTP/1.1

L accept: // indicates the list of media types that can be responded to by an accepted request.

L accept-language: // limits the preferred language in the Request Response to simplified Chinese. Otherwise, the default value is used.

L accept-encoding: // limits the acceptable content encoding values in the response, indicating that the additional content is decoded using gzip and deflate.

L User-Agent: // defines the user proxy, that is, the browser type for sending the request is Mozilla/4.0

L HOST: Host IP // defines the target host

L connection: keep-alive \ r \ N // tell the server to use persistent connection

HTTP Response Message

L HTTP Version: HTTP/1.1 // The server uses HTTP/1.1

L HTTP status: 200 // The request is successful. The information can be read and contained in the response message.

L date: // The time when the server retrieves the object from the file system, inserts it into the response message, and sends the Response Message.

L server: // indicates that the engraved packet is generated by an Apache/2.0.52 server.

L x-powered-by: // indicates a dynamic webpage using PHP (version ).

L set-COOKIE ://

L vary ://

L Content-Length: // indicates the object length.

L connection: // tell the client to keep the connection after the packet is sent

L Content-Type: // indicates that the object in the object is an HTML document.

L binary data: // binary data

Note: In the Response Request from the server, we can view the access information from the status code. The status code indicates the response type, which is commonly used as follows:

L 1 × Reserved

L 2 × indicates that the request is successfully received

L 3×× further refine the request to complete the request

L 4×× customer Error

L 5×× Server Error
Status Code
Status information
Description

100
Continue
The initial request has been accepted, and the customer should continue to send the rest of the request. (New HTTP 1.1)

101
Switching protocols
The server converts a client-compliant request to another protocol (New in HTTP 1.1)

200
OK
Everything works normally. The response documents for get and post requests follow.

201
Created
The server has created a document and the location header provides its URL.

202
Accepted
The request has been accepted, but the processing has not been completed.

203
Non-authoritative information
The document has been returned normally, but some response headers may be incorrect because the document is copied (New in HTTP 1.1 ).

204
NO content
If no new document exists, the browser should continue to display the original document. This status code is useful if the user regularly refreshes the page 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 the content it shows. Used to force the browser to clear the input content of the form (New in HTTP 1.1 ).

206
Partial content
The client sends a GET request with a range header, and the server completes the request (New in HTTP 1.1 ).

300
Multiple Choices
Documents requested by the customer can be found in multiple locations, which are listed in the returned documents. If the server needs to give priority, it should be specified in the location response header.

301
Moved permanently
The document requested by the customer is elsewhere. The new URL is provided in the location header, and the browser should automatically access the new URL.

302
Found
Similar to 301, but the new URL should be treated as a temporary alternative, rather than permanent. Note that the corresponding status information in http1.0 is "Moved temporatily ".

When this status code appears, the browser can automatically access the new URL, so it is a very useful status code.

Note that this status code can be replaced with 301 sometimes. For example, if the browser mistakenly requests http: // host /~ If the user (with a slash 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 redirection target document specified by the location header should be extracted through get (New in HTTP 1.1 ).

304
Not modified
The client has a buffered document and sends a conditional request (generally, the IF-modified-since header is provided to indicate that the customer only wants to update the document on a specified date ). The server tells the customer that the original buffer documentation can still be used.

305
Use proxy
The document requested by the customer should be extracted by the proxy server specified by the location header (New in HTTP 1.1 ).

307
Temporary redirect
It is the same as 302 (found. Many browsers mistakenly respond to the 302 response for redirection. Even if the original request is post, it can only be redirected when the POST request actually responds to 303. For this reason, HTTP 1.1 adds 307 to clear the region code in several states: When a 303 response occurs, the browser can follow the redirected get and post requests; if a 307 response occurs, the browser can only follow the redirection to get requests. (New HTTP 1.1)

400
Bad request
The request has a syntax error.

401
Unauthorized
The customer attempted to access the password-protected page without authorization. The response contains a WWW-Authenticate header. the browser displays the username/password dialog box accordingly, and then sends a request again after entering the appropriate authorization header.

403
Forbidden
Resource unavailable. The server understands the customer's request, but rejects the request. This is usually caused by permission settings for files or directories on the server.

404
Not found
The resource at the specified location cannot be found. This is also a common response.

405
Method not allowed
Request methods (get, post, Head, delete, put, Trace, etc.) are not applicable to specified resources. (New HTTP 1.1)

406
Not acceptable
The specified resource has been found, but its MIME type is incompatible with the one specified by the customer in the accpet header (New in HTTP 1.1 ).

407
Proxy authentication required
Similar to 401, the customer must first be authorized by the proxy server. (New HTTP 1.1)

408
Request timeout
The customer has not issued any request within the waiting time of the server license. The customer can repeat the same request later. (New HTTP 1.1)

409
Conflict
It is usually related to put requests. The request cannot be successful because the request conflicts with the current status of the resource. (New HTTP 1.1)

410
Gone
The requested document is no longer available and the server does not know which address to redirect. It differs from 404 in that if 407 is returned, the document permanently leaves the specified position, and 404 indicates that the document is unavailable for unknown reasons. (New HTTP 1.1)

411
Length required
The server cannot process the request unless the client sends a Content-Length header. (New HTTP 1.1)

412
Precondition failed
Some preconditions specified in the request header fail (HTTP 1.1 is new ).

413
Request Entity too large
The size of the target document exceeds the size that the server is willing to process. If the server thinks it can process the request later, it should provide a retry-after header (New in HTTP 1.1 ).

414
Request URI Too Long
The URI is too long (New in HTTP 1.1 ).

416
Requested range not satisfiable
The server cannot meet the range header specified by the customer in the request. (New HTTP 1.1)

500
Internal Server Error
The server encounters unexpected circumstances and cannot complete the customer's request.

501
Not Implemented
The server does not support the functions required to implement the request. For example, the customer sends a put request not supported by the server.

502
Bad Gateway
When the server acts as a gateway or proxy, in order to complete the request to access the next server, but the server returns an invalid response.

503
Service unavailable
The server fails to respond due to maintenance or heavy load. For example, Servlet may return 503 when the database connection pool is full. When the server returns 503, A retry-after header can be provided.

504
Gateway timeout
Used by a proxy or gateway server, it indicates that the remote server cannot receive a response in a timely manner. (New HTTP 1.1)

505
HTTP Version Not Supported
The server does not support the HTTP Version specified in the request. (New HTTP 1.1)