已经登录后如何防止用户访问登录页面？

Question

I want to prevent user to access login page when its already logged in. In header page I've checked session so that user can't access any admin page without logging in. What code do I have to write in header page and session page to prevent user access login page while already logged in?

Here's my session class

public static function init(){
    session_start();
}
public static function set($key, $val){
    $_SESSION[$key]=$val;
}
public static function get($key){
    if (isset($_SESSION[$key])) {
        return $_SESSION[$key];
    } else {
        return false;
    }
}
public static function checkSession(){
    self::init();
    if (self::get("login")==false) {
        self::destroy();
        header("Location:login.php");
    }  
}

public static function destroy(){
    session_destroy();

Answer 1

And this code avoid the user back to the page after log out

if(!isset($_SESSION['login_user'])){
  header("location:login.php");
  location.reload();
 }

This code is to avoid repeated login from the user

if(isset($_SESSION['login_account_id'])){
      header('location: /index.php');
  }

Answer 2

检查登录页面上的会话变量值（如果存在），然后重定向或仪表板或主页（如果不存在），则在登录页面上重定向会话变量值。

Answer 3

Write your login page like this:

<?php
   session_start();
   if(isset($_SESSION['key'])){
      header('home.php');
   } else {
      //Paste login page code here
   }
?>

Answer 4

<?php
// Initialize the session
session_start();

// If user is already logged in, redirect to index
if($_SESSION["loggedin"] == true){
    header("location: index.php");
}

?>