我有一个页面(index.php)，它有一个登录表单。当用户登录时，它检查凭据，如果正确，则创建会话，设置两个变量，auth为yes, user为username，并通过回显javascript window.location.href命令重定向到另一个页面(pihome.php)。这就是问题开始的地方。在此页上，如果我运行session_start()，它曾经说会话已经创建，忽略，但我能够从前一页访问变量。现在使用session_status()的if条件，如果session_start()工作。我在这个页面上有一个登出按钮，可以转到另一个页面(Logout.php)。在该页上，当我尝试运行session_destroy()时，它说会话尚未启动，当我尝试echo变量时，它说它们尚未定义。
在浏览解决方案时，我看到某些解决方案适用于未被转移的变量，但我可以在pihome.php页面上访问它们，但logout.php不让我访问它们或执行session_destroy()。我想知道我是否正确使用会话，如果我应该将session_start()放在每一页的开头，以及如何正确访问变量。谢谢!
index . php
<!DOCTYPE html>
<html>
<head>
<title>PiHome Login</title>
<meta name="viewport" content="width=device-width, initial-scale=1">
<link rel="stylesheet" href="http://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/css/bootstrap.min.css">
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.3/jquery.min.js"> </script>
<script src="http://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/js/bootstrap.min.js"> </script>
<link rel="stylesheet" href="standardstyle.css">
</head>
<body id="override-background">
<?php
session_start();
?>
<?php
if(isset($_SESSION["Auth"])){
if($_SESSION["Auth"] == "yes"){
echo '<script type="text/javascript">
window.location.href = "pihome.php";
</script>';
}
else{
}}
else{
}
?>
<div class="jumbotron">
<h1 class="text-center">PiHome<br/><small>v1.0.0</small></h1>
</div>
<div class="container-fluid">
<div class="well col-3">
<img src="piHome.png" alt="piHome_logo" class="img-rounded" style="display:block;"></img>
<h3 class="text-center">Login</h3>
<form role="form" action="index.php" method="post">
<div class="form-group">
<label for="user">Username</label>
<input type="text" class="form-control" id="email" name="user">
</div>
<div class="form-group">
<label for="pwd">Password:</label>
<input type="password" class="form-control" id="pwd" name="pass">
</div>
<div class="checkbox">
<label><input type="checkbox" name="remember"> Remember me</label>
</div>
<input type="submit" class="btn btn-primary btn-block" value="Login">
<form>
</div>
</div>
<?php
$server = "localhost";
$user = "root";
$pass = "";
$db = "pihome_users";
//Database Connection
$conn = mysqli_connect($server, $user, $pass, $db);
//Check Connection
if($conn->error){
die("Connection Failed: "+ $conn.error);
}
if(isset($_POST['user'])){
//echo "Set<br>";
//User Authentication
$inputuser = $conn->escape_string($_POST['user']);
$inputpass = $conn->escape_string($_POST['pass']);
//echo $inputuser."<br>";
//echo $inputpass."<br>";
$sql = 'SELECT * FROM users WHERE username="'.$inputuser.'"';
//echo $sql;
//Execute
$result = $conn->query($sql);
if($conn->error){
echo "Load Error";
}
if ($result->num_rows > 0) {
$row = $result->fetch_assoc();
if($inputpass == $row["password"]){
echo '<div class="alert alert-success fade in">
<a href="#" class="close" data-dismiss="alert" aria- label="close">x</a>
Your credentials are correct
</div>';
echo '<script type="text/javascript">
window.location.href = "pihome.php";
</script>';
$_SESSION["Auth"] = "yes";
$_SESSION["User"] = $inputuser;
}else{
echo '<div class="container-fluid"><div class="alert alert-danger fade in">
<a href="#" class="close" data-dismiss="alert" aria- label="close">x</a>
Your username or password is incorrect!
</div></div>';
$_SESSION["Auth"] =false;
//echo "Success";
}
} else {
//echo "Failed";
}
}
else{
//echo "Not Set";
}
?>
</body>
</html>
pihome.php
<!DOCTYPE html>
<html>
<head>
<title>PiHome</title>
<meta name="viewport" content="width=device-width, initial-scale=1">
<link rel="stylesheet" href="http://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/css/bootstrap.min.css">
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.3/jquery.min.js"> </script>
<script src="http://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/js/bootstrap.min.js"> </script>
<link rel="stylesheet" href="standardstyle.css">
</head>
<body>
<?php
$sessionstate = session_status();
if($sessionstate == 1){
session_start();
echo "Started";
}
?>
<?php
if(isset($_SESSION["Auth"])){
if($_SESSION["Auth"] != "yes"){
echo '<script type="text/javascript">
window.location.href = "index.php";
</script>';
echo "You are logged in as: ".$_SESSION["User"];
}else{
echo "Auth Passed";
$_SESSION["Auth"] = "yes";
}
}else{
echo '<script type="text/javascript">
window.location.href = "index.php";
</script>';
}
?>
<div class="jumbotron">
<h1 class="text-center">PiHome<br/><small>v1.0.0</small></h1>
</div>
<div class="container-fluid">
<div class="well col-3">
<h3 class="text-center">Status</h3>
<div id="status">
</div>
</div>
<script>
function AJAX_JSON_Req( url )
{
var AJAX_req = new XMLHttpRequest();
AJAX_req.open( "GET", url, true );
AJAX_req.setRequestHeader("Content-type", "application/json");
AJAX_req.onreadystatechange = function()
{
if( AJAX_req.readyState == 4 && AJAX_req.status == 200 )
{
var response = JSON.parse( AJAX_req.responseText );
//document.write( response.controls[0].type );
document.getElementById("status").innerHTML = response.controls[0].type + " " + response.controls[0].state;
}
}
AJAX_req.send();
}
AJAX_JSON_Req( 'status.json' );
</script>
<a href="logout.php">Logout</a>
</div>
</body>
<html>
logout.php
<?php
$sessionstate = session_status();
if($sessionstate == 1){
session_start();
echo "Started";
session_unset();
}
else if($sessionstate == 2){
session_destroy();
echo "destroyed";
}
/*echo '<script type="text/javascript">
window.location.href = "index.php";
</script>';*/
?>
我通过在任何输出之前使用session_start()解决了这个问题，包括上面评论中rjdown建议的<!DOCTYPE html>。