PHP code example to realize that member account can only log in uniquely

The content of this article is about the code example of PHP realizing that member accounts can only be logged in uniquely. It has certain reference value. Friends in need can refer to it. I hope it will be helpful to you.

Reappearance

The same member account is restricted to single sign-in on the same device (computer, mobile phone, Ipad, etc.). After repeated login, the original login page will jump directly to the login page. page and need to log in again to access it normally.

Principle Analysis

After account A logs in on computer A, account A logs in again using computer B. When computer A requests the page, it prompts the message "Re-login" and Jump to the login page

Idea analysis:

After account A logs in on computer A, write the SESSION ID into the TXT file, and perform a verification every time the page is accessed (compare txt file is the same as the value of the currently logged in session_id)

Example

1. Entry and verification (index.php)

<?php
session_start();
$uid = 10;
if(is_login($uid)){
 header(&#39;location:loginSuccess.php&#39;);
}else{  $
getLogSessionId = file_get_contents(&#39;session_log/&#39;.$uid.&#39;.txt&#39;);  
if($getLogSessionId){    
echo "已在其他地方登录，请重新登录";    
echo "<br>";   
 echo "5秒后跳转到登录页面!";
    header("refresh:5;url=login.php");
  }else{    
  echo &#39;第一次登录...&#39;;    
  echo "<br>";    
  echo "3秒钟后跳转到登录页面!";
    header("refresh:3;url=login.php");
  }
}
/**
* 通过登录时写入文件session_id和当前登录设备后生成的session_id进行比较，相同则是同一台设备登录，不同则在别的地方登录
*/
function is_login($uid){
  $getLogSessionId = file_get_contents(&#39;session_log/&#39;.$uid.&#39;.txt&#39;);  
  if($getLogSessionId == session_id()){    
  return true;
  }else{   
   return false;
  }
}

2. Login .php)

<?php
session_start();
echo "登录中....";echo &#39;<br>&#39;;
$uid = 10;
file_put_contents(&#39;session_log/&#39;.$uid.&#39;.txt&#39;,session_id());
echo "登录完成";

3. Log in successfully (loginSuccess.php)

<?phpecho "我登录成功了!";

4. Save the sessionId folder (session_log) and test the code. You need to create one manually or give permission to automatically generate the file.

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