Detailed explanation of session time setting in php

In most forums, you can choose the expiration time when logging in, such as saving for one week, saving for one month, etc. At this time, you can set the login expiration time through Cookie. There are mainly the following methods to set the session expiration time:

1. The client does not prohibit cookies

(1) Use session_set_cookie_params()Set Session expiration time. This function is Session combined with Cookie to set expiration time. If you want the Session to expire after one minute, the code example is as follows:

<?php
 $time = 1*60;                   //设置session失效时间
 session_set_cookie_params($time);      // 使用函数
 session_start();                 //初始化  session
 $_SESSION["username"] = &#39;tom&#39;;
?>

Note: session_set_cookie_params() must be called before session_start().

Note: This function is not recommended and may cause problems on some browsers. Therefore, the expiration time is generally set manually.

(2) Use the setcookie() function to set the expiration time for the Session. To make the Session expire after one minute, the code example is as follows:

<?php
 session_start();
 // session失效时间
 $time = 1*60;                    
 // 使用 setcookie 手动设置 session失效时间      
 setcookie(session_name(),session_id(),time()+$time.&#39;/&#39;);    
 $_SESSION["username"] = &#39;tom&#39;;
?>

Note: In the setcookie() function of the above example code, session_name is the name of the Session, and session_id is the identification of the client user. Because session_id is a randomly generated unique name, the Session is relatively safe. The expiration time is the same as that of Cookie. The last parameter is optional and is the path where the Cookie is placed.

2. Disable Cookies on the client

When the client disables Cookies, the transfer between Session pages will fail. You can disable Cookies on the client. Imagine a large supermarket chain. If you apply for a membership card in one of the supermarkets, but there is no Internet connection between the supermarkets, the membership card can only be used in that supermarket. There are several ways to solve this problem:

(1) Remind users that they must turn on cookies before logging in. This is the practice of many forums.

(2) Set session.use_trans_sid =1 in the php.ini file, or turn on the -enable-trans-sid option when compiling to let PHP automatically pass session_id across pages.

(3) Pass the session_id in the hidden form through the GET method.

(4) Use a file or database to store session_id, and call it manually during transfer between pages.

The second method above will not be introduced in detail because users cannot modify the php.ini file in the server. In the third method, we cannot use Cookie to set the expiration time, but the login status does not change. The fourth and most important one can be used if you encounter

session files that slow down the server when developing enterprise-level websites. Here we introduce the third method of transmission using the GET method. The sample code is as follows. The code for receiving the page header:

<?php
  $session_name = session_name();        //取得 session 名称
  $session_id = $_GET[$session_name];    // 取得 session_id GET方式
  session_id($session_id);               // 关键步骤
  session_start();
  $_SESSION[&#39;admin&#39;] = &#39;soft&#39;;
?>

Description: Session is generated after requesting the page. A session_id. If Cookie is disabled at this time, the session_id cannot be passed. When requesting the next page, a session_id will be regenerated, which will cause the session to fail to be passed between pages.

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