Status code interpretation and corresponding error handling methods in PHP language development

In web development, HTTP status codes are often involved, and PHP, as a commonly used web programming language, also needs to process and interpret status codes. The status code reflects the processing result of the request. Correctly handling status codes and error messages can help developers better debug code and improve user experience.

This article will introduce the status codes that often appear in PHP language development and the corresponding error handling methods.

1. 1xx (message status code)

100 (Continue): Indicates that the client should continue its request.

101 (switch protocol): Indicates that the server will comply with the client's request and switch to another protocol. For example, change to websocket protocol.

These status codes usually do not require additional processing and are handled automatically.

2. 2xx (success status code)

200 (success): Indicates that the request has been successfully processed, commonly used for GET/POST requests.

201 (Created): Indicates that the request has been successfully processed and a new resource has been created.

202 (Accepted): Indicates that the server has accepted the request but has not completed processing. For example, generating time-consuming report files.

204 (no content): Indicates that the request has been successfully processed, but no content was returned. For example, after deleting a resource, a 204 status code is returned.

This type of status code usually indicates successful processing results and no additional error handling is required.

3. 3xx (Redirect status code)

301 (Permanently moved): Indicates that the requested resource has been permanently moved to a new location. Usually used for website revision, domain name change and other operations.

302 (Temporary Move): Indicates that the requested resource has been temporarily moved to a new location. Usually used for operations such as temporary page jumps.

304 (Unmodified): Indicates that the requested resource has not been modified and can be obtained from the browser cache. Typically used for static resources.

Handling these status codes usually requires redirecting to a new URL, or checking the cache, etc.

4. 4xx (Client error status code)

400 (Bad request): Indicates an error in the request, usually due to incorrect, missing, incorrect format, etc. parameters.

401 (Unauthorized): Indicates that the user is not authorized or the authorization has expired. Usually used for operations that require login.

403 (Forbidden): Indicates that the user does not have permission to access the resource. Usually used for operations such as authentication failure and unauthorized processing.

404 (Not Found): Indicates that the requested resource does not exist. Usually used for operations such as accessing non-existent pages and files.

422 (Unable to process entity): Indicates that the request cannot be processed by the server, usually because the requested entity data format is incorrect.

The processing of these status codes usually requires outputting error messages that can be understood by users, such as displaying "no access rights" and other prompts.

5. 5xx (server error status code)

500 (server error): Indicates an internal error in the server and the request cannot be completed.

502 (Bad Gateway): Indicates that the application server cannot respond, usually occurs in load balancing. It needs to be checked on application servers such as nginx.

504 (Gateway Timeout): Indicates that the application server is unresponsive, usually appearing in load balancing. The performance of the application server needs to be checked.

These status codes usually require operations such as error logging and troubleshooting server performance issues.

Based on the above status code description, we need to customize the error handling method according to the status code during development to make the error message more friendly and improve the user experience. Usually we can customize error handling by setting the configuration of htaccess or nginx.

For example, we can make the following settings in .htaccess:

ErrorDocument 404 /404.html

ErrorDocument 500 /500.html

When a 404 or 500 status code occurs, the user will be redirected to the defined custom error page.

At the same time, we can also use the try...catch operation to capture exceptions when the PHP program is running, and output or log the exception information.

Summary:

Status code is an important part of web development. Correct interpretation and processing of status codes is conducive to optimizing user experience and code debugging. Developers need to pay attention to the uses and processing methods of different status codes, and handle status codes carefully during development.

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