PHP真的很新。我有一个指向索引页面的登录页面。在索引页面上有一个注销按钮。因此，当我单击注销时，它将重定向到登录页面，并在我单击后退按钮时取消设置$ _SESSION。但它并没有破坏会议。它仍然将我重定向到索引页面。但是已经有了未设定的值。看起来像session_destroy（）;不管用。如果有人可以帮助我，那真的会很棒。谢谢！
这是我的login.php
<?php
require('session.php');
?>
<html>
<head>
<!-- CSS -->
<link rel="stylesheet" href="css/style-login.css">
<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.3.1/css/bootstrap.min.css" integrity="sha384-ggOyR0iXCbMQv3Xipma34MD+dH/1fQ784/j6cY/iJTQUOhcWr7x9JvoRxT2MZw1T" crossorigin="anonymous">
</head>
<body>
<div class="header">
<img src = "img/usc_logo.png">
</div>
<div class="box">
<form id="loginform" class="form-horizontal" role="form" action = "" method = "POST">
<div style="margin-bottom: 25px" class="input-group">
<span class="input-group-addon"><i class="glyphicon glyphicon-user"></i></span>
<input type="text" class="form-control" name="username" value="" placeholder="ID Number" required/>
</div>
<div style="margin-bottom: 25px" class="input-group">
<span class="input-group-addon"><i class="glyphicon glyphicon-lock"></i></span>
<input type="password" class="form-control" name="password" placeholder="Password" required>
</div>
<div style="margin-top:10px" class="form-group">
<!-- Button -->
<div class="col-sm-12 controls">
<input class="submit-1" type = "submit" value = " Log in " name= "submit"/><br/><br/>
Not a member yet?
<a href="register.php" class="button">Register</a><br/><br/>
<center>
<span style='color:#e60000; font-size:15px;'><b><?php echo $error; ?></b></span>
</center>
</div>
</div>
</form>
</div>
<!-- JS -->
<script src="https://code.jquery.com/jquery-3.3.1.slim.min.js" integrity="sha384-q8i/X+965DzO0rT7abK41JStQIAqVgRVzpbzo5smXKp4YfRvH+8abtTE1Pi6jizo" crossorigin="anonymous"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.7/umd/popper.min.js" integrity="sha384-UO2eT0CpHqdSJQ6hJty5KVphtPhzWj9WO1clHTMGa3JDZwrnQq4sF86dIHNDz0W1" crossorigin="anonymous"></script>
<script src="https://stackpath.bootstrapcdn.com/bootstrap/4.3.1/js/bootstrap.min.js" integrity="sha384-JjSmVgyd0p3pXB1rRibZUAYoIIy6OrQ6VrjIEaFf/nJGzIxFDsf4x0xIM+B07jRM" crossorigin="anonymous"></script>
</body>
</html>
这是我的index-admin.php
<?php
require('session.php');
?>
<html lang="en">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
<meta name="description" content="">
<meta name="author" content="Mark Otto, Jacob Thornton, and Bootstrap contributors">
<meta name="generator" content="Jekyll v3.8.5">
<title>Admin DCIS</title>
<link rel="canonical" href="https://getbootstrap.com/docs/4.3/examples/album/">
<!-- Bootstrap core CSS -->
<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.3.1/css/bootstrap.min.css" integrity="sha384-ggOyR0iXCbMQv3Xipma34MD+dH/1fQ784/j6cY/iJTQUOhcWr7x9JvoRxT2MZw1T" crossorigin="anonymous">
<style>
.bd-placeholder-img {
font-size: 1.125rem;
text-anchor: middle;
-webkit-user-select: none;
-moz-user-select: none;
-ms-user-select: none;
user-select: none;
}
@media (min-width: 768px) {
.bd-placeholder-img-lg {
font-size: 3.5rem;
}
}
</style>
<!-- Custom styles for this template -->
<link href="album.css" rel="stylesheet">
</head>
<body>
<header>
<div class="collapse bg-dark" id="navbarHeader">
<div class="container">
</div>
</div>
<div class="navbar navbar-dark bg-dark shadow-sm">
<div class="container d-flex justify-content-between">
<a href="#" class="navbar-brand d-flex align-items-center">
<strong>Hello, <?php echo $_SESSION['user_role'] ?></strong>
</a>
<a href="logout.php" class="btn btn-danger">Logout</a>
</div>
</div>
</header>
<main role="main">
<section class="jumbotron text-center">
<div class="container">
<h1 class="jumbotron-heading">Name of Requestee</h1>
<button href="#" class="btn btn-primary my-2">Accept</button>
<button href="#" class="btn btn-secondary my-2">Reject</button>
</p>
</div>
</section>
<script src="https://code.jquery.com/jquery-3.3.1.slim.min.js" integrity="sha384-q8i/X+965DzO0rT7abK41JStQIAqVgRVzpbzo5smXKp4YfRvH+8abtTE1Pi6jizo" crossorigin="anonymous"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.7/umd/popper.min.js" integrity="sha384-UO2eT0CpHqdSJQ6hJty5KVphtPhzWj9WO1clHTMGa3JDZwrnQq4sF86dIHNDz0W1" crossorigin="anonymous"></script>
<script src="https://stackpath.bootstrapcdn.com/bootstrap/4.3.1/js/bootstrap.min.js" integrity="sha384-JjSmVgyd0p3pXB1rRibZUAYoIIy6OrQ6VrjIEaFf/nJGzIxFDsf4x0xIM+B07jRM" crossorigin="anonymous"></script>
</body>
</html>
这是logout.php
<?php
session_start();
session_unset();
session_destroy();
header('Location: login.php');
?>
如果需要，这是我的session.php
<?php
require("dbconnector.php");
$error="";
session_start();
if(isset($_POST['submit'])){
require ('dbconnector.php');
$query = "SELECT * FROM user WHERE username = '{$_POST['username']}' AND password = '{$_POST['password']}'";
$con = mysqli_query($conn, $query);
if ($con->num_rows == 1){
$row = mysqli_fetch_assoc($con);
$_SESSION['user_role'] = $row['user_role'];
mysqli_close($conn);
if ($_SESSION['user_role'] == 'Admin'){
header('Location: index-admin.php');
}
elseif($_SESSION['user_role'] == 'Student') {
header('Location: index.php');
}
}
else{
$error = "ID Number or Password is Invalid";
header("refresh: 5");
}
}
?>
您需要在客户端正确销毁会话和会话的cookie。我建议不要在登录页面上写这个，而是在logout.php这个重定向到login.html的特定页面上写。
<?php
session_start(); // Start by calling the session.
$_SESSION = array(); // Reset the session's variables.
$params = session_get_cookie_params();
setcookie(session_name(), '', time() - 42000, $params["path"], $params["domain"], $params["secure"], $params["httponly"]); //Invalids session's cookie.
session_destroy(); //Finally destroy it.
//If you want to redirect
header("Location: <URL>");
?>