如何验证访问令牌并在无效时获取新的访问令牌？

Question

我的应用程序工作正常，一切正常，但是当用户注销或两小时后返回或更改密码或删除应用程序然后尝试再次添加它时，我会收到如下错误，其中包含每个错误的原因：

Fatal error: Uncaught OAuthException: Error validating access token: The session is invalid because the user logged out. thrown in /home/user/public_html/new_fb_app/src/base_facebook.php on line 1028

另外，如果我在出现此错误后尝试刷新，该应用程序将正常工作。所以我想这与应用程序尝试使用最后一个访问令牌（无效）有关。

这是我的代码：

<?php
$user = null; //facebook user uid
try{
include_once "src/facebook.php";
}
catch(Exception $o){
echo '<pre>';
print_r($o);
echo '</pre>';
    }
// Create our Application instance (replace this with your appId and secret).
$facebook = new Facebook(array(
  'appId'       => 'my appId',
  'secret'      => 'my app secret',
  'fileUpload'  => true
));

// Get User ID
$user       = $facebook->getUser();
$loginUrl   = $facebook->getLoginUrl(
    array(
    'scope' => 'read_stream, publish_stream, photo_upload, user_photos'
    )
);

if ($user) {
try {
// Proceed knowing you have a logged in user who's authenticated.
$access_token = $facebook->getAccessToken();
} catch (FacebookApiException $e) {
//you should use error_log($e); instead of printing the info on browser
d($e);  // d is a debug function defined at the end of this file
$user = null;
}
}
if (!$user) {
echo "<script type='text/javascript'>top.location.href = '$loginUrl';</script>";
exit;
    }
function d($d){
echo '<pre>';
print_r($d);
echo '</pre>';
}
?>

Answer 1

用户注销时清空 cookie 或会话？