php - 如何查看某人是否在线？

Question

所以我在 php 中做了一个简单的登录系统，我如何继续在 php 上创建一个函数来检查某人是否在线也可以在php

登录系统

<?php
if (empty($_POST) === false) {
$username = $_POST['username'];
$password = $_POST['password'];

if (empty($username) === true || empty($password) === true) {
   $errors[] = 'Please Enter a username and password';
   } else if (user_exists($username) === false) {
   $errors[] ='Sorry but the user you entered dose not exist';
  } else if (user_active($username) === false) {
   $errors[] ='You have not activated your account please check your email to activate your account';
  } else {
if (strlen($password) > 32){
$errors[] ='Passwords to long !';
}
 $login = login($username, $password);
 if ($login === false) {
 $errors[] ='incorrect username or password';
 } else {
$_SESSION['user_id'] = $login;
 header('Location: index.php');
 exit();
       }
    }
  } else {
  $errors[] = 'No information received';
}
echo output_errors($errors);
?>

Answer 1

您可以使用 session 来实现此目的:

http://php.net/manual/en/book.session.php

session 的简单使用:

// Start the session
if(!session_id())
    session_start();

$_SESSION["the_user"] = true;

// To check if the session is alive
if(!empty($_SESSION["the_user"]))
    echo "User is online !";
else
    echo "User isn't online!";

// Delete the session
unset($_SESSION["the_user"]);

请注意，这只是 session 的一个简单用法，即使用户离开该站点， session 也会保持事件状态。但这会持续几分钟。 ( session 的过期时间)