重定向后保留会话

如果我在调用重定向函数之前var_dump我的会话变量，它看起来没有问题。然而，在重定向到外部clickabank的支付页面后，我不再能够在支付后访问页面上的会话变量。

我使用下面的函数重定向:

public function redirect($url) {
if(!headers_sent()) {
    //If headers not sent yet... then do php redirect
    header('Location: '.$url);
    exit();
} else {
    //If headers are sent... do javascript redirect... if javascript disabled, do html redirect.
    echo '<script type="text/javascript">';
    echo 'window.location.href="'.$url.'";';
    echo '</script>';
    echo '<noscript>';
    echo '<meta http-equiv="refresh" content="0;url='.$url.'" />';
    echo '</noscript>';
    exit();
}
exit();
}

我在使用会话的所有脚本上使用session_start。

下面的页面是使重定向

<?php 
if(!session_id())  session_start();
require_once("core.php");
$core = new coreOptions();
$options = $core->getChosenOptions();
$numOptions = count($options);

$url = "";

switch($numOptions) {
case 1:
$url = $core->url1Options;
break;
case 2:
$url = $core->url2Options;
break;
case 3:
$url = $core->url3Options;
break;
case 4:
$url = $core->url4Options;
break;
case 5:
$url = $core->url5Options;
break;
case 6:
$url = $core->url6Options;
break;
case 7:
$url = $core->url7Options;
break;
case 8:
$url = $core->url8Options;
break;
case 9:
$url = $core->url9Options;
break;
default:
$url = $core->urldefaultOptions;
break;
}

$core->redirect($url);
exit();
?>

下面是core.php

.....
// get options
public function getChosenOptions(){
if (isset($_SESSION["chosenOptions"])) return $_SESSION["chosenOptions"];
return false;
}
// set options
public function setChosenOptions($c) {
$_SESSION["chosenOptions"] = $c;
}
 .....
 // function to redirect to given page
public function redirect($url) {
if(!headers_sent()) {
    //If headers not sent yet... then do php redirect
    header('Location: '.$url);
    exit();
} else {
    //If headers are sent... do javascript redirect... if javascript disabled, do html redirect.
    echo '<script type="text/javascript">';
    echo 'window.location.href="'.$url.'";';
    echo '</script>';
    echo '<noscript>';
    echo '<meta http-equiv="refresh" content="0;url='.$url.'" />';
    echo '</noscript>';
    exit();
}
exit();
}
.....

下面的页面是我想访问$_SESSION["chosenOptions"]的页面。为什么下面的页面无法访问会话变量，尽管在进行重定向的页面中正确设置了会话变量?:

 <?php if(!session_id())  session_start();

require_once("core.php");
$core = new coreOptions();
$uid = $core->uid();
$options = $core->getChosenOptions();
var_dump($options); // this line shows NULL. Why ?
if (empty($options)) exit("Options Is Empty");
if (count((array)$options)>0) {
try {
    $conn = new PDO() // stripped conn data
    $conn->exec("SET CHARACTER SET utf8");      // Sets encoding UTF-8
    $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    $sql = "INSERT INTO availablecommands (for_whom, oname, is_available) VALUES (:fw, :on, :ia)";
    $statement = $conn->prepare($sql);
    foreach($options as $o) {
    $statement->bindValue(":fw", $uid);
    $statement->bindValue(":on", $o);
    $statement->bindValue(":ia", 1);
    $count = $statement->execute();
    $conn = null;       // Disconnect
    }
    }
    catch(PDOException $e) {
        echo $e->getMessage();
    }

}

$core->redirect("dashboard.php");

?>