Facebook PHP SDK 中的访问令牌是什么?

What is the access token in Facebook PHP SDK?

对 PHP 很陌生,我正在尝试使用 Facebook PHP SDK 编写程序,现在我正在尝试让以下教程发挥作用,https://developers.facebook.com/docs/php/howto/example_retrieve_user_profile,但我不断收到错误。我认为这可能与访问令牌有关。我不知道我是否应该在那里放别的东西。如果我是,我如何获得我的访问令牌?现在我只是按照教程中的方式保留它。但是错误是说第 2 行有问题,所以问题可能就在那里。不太确定。所以任何帮助将不胜感激!

错误信息

[north@oreo ~/Facebook]$ php Practice_2.php

Fatal error: Uncaught Error: Class 'Facebook\Facebook' not found in /usr/home/north/Facebook/Practice_2.php:2
Stack trace:
#0 {main}
  thrown in /usr/home/north/Facebook/Practice_2.php on line 2

Practice_2.php

<?php
$fb = new Facebook\Facebook([
  'app_id' => '{}',
  'app_secret' => '{}',
  'default_graph_version' => 'v3.3',
  ]);

try {
  // Returns a `Facebook\FacebookResponse` object
  $response = $fb->get('/me?fields=id,name', '{access-token}');
} catch(Facebook\Exceptions\FacebookResponseException $e) {
  echo 'Graph returned an error: ' . $e->getMessage();
  exit;
} catch(Facebook\Exceptions\FacebookSDKException $e) {
  echo 'Facebook SDK returned an error: ' . $e->getMessage();
  exit;
}

$user = $response->getGraphUser();

echo 'Name: ' . $user['name'];
// OR
// echo 'Name: ' . $user->getName();

来自docs

When someone connects with an app using Facebook Login and approves the request for permissions, the app obtains an access token that provides temporary, secure access to Facebook APIs.