Two implementation methods of php page rollback

Method 1, use the Header method to set the message header Cache-control

header('Cache-control: private, must-revalidate'); //支持页面回跳

Method 2, use session_cache_limiter method

//必须写在session_start方法之前，否则报错。
session_cache_limiter('private, must-revalidate');

Attached, Cache-Control message header field description Cache-Control specifies the caching mechanism that requests and responses follow. Setting Cache-Control in a request message or response message does not modify the caching process during the processing of another message. The cache instructions during the request include no-cache, no-store, max-age, max-stale, min-fresh, only-if-cached, and the instructions in the response message include public, private, no-cache, no-store, no-transform, must-revalidate, proxy-revalidate, max-age.

The meaning of each message command: 1. Public indicates that the response can be cached by any cache area. 2. Private indicates that all or part of the response message for a single user cannot be processed by the shared cache. This allows the server to only describe a partial response from a user that is not valid for other users' requests. 3. no-cache indicates that the request or response message cannot be cached 4. no-store is used to prevent important information from being released unintentionally. Sending it in the request message will cause both the request and response messages to use caching. 5. max-age indicates that the client can receive responses with a lifetime no greater than the specified time (in seconds). 6. min-fresh indicates that the client can receive a response with a response time less than the current time plus the specified time. 7. max-stale indicates that the client can receive response messages beyond the timeout period. If you specify a value for max-stale messages, the client can receive response messages that exceed the specified value of the timeout period. For more detailed information about cache-control, please refer to: php file header information detailed explanation .

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