Facebook SDK V4获得名称

Question

For example, I want to retrieve my name using Facebook PHP SDK 4. For that I use this code

<?php

require_once( 'Facebook/HttpClients/FacebookHttpable.php' );
require_once( 'Facebook/HttpClients/FacebookCurl.php' );
require_once( 'Facebook/HttpClients/FacebookCurlHttpClient.php' );

require_once( 'Facebook/Entities/AccessToken.php' );
require_once( 'Facebook/Entities/SignedRequest.php' );

require_once( 'Facebook/FacebookSession.php' );
require_once( 'Facebook/FacebookRedirectLoginHelper.php' );
require_once( 'Facebook/FacebookRequest.php' );
require_once( 'Facebook/FacebookResponse.php' );
require_once( 'Facebook/FacebookSDKException.php' );
require_once( 'Facebook/FacebookRequestException.php' );
require_once( 'Facebook/FacebookOtherException.php' );
require_once( 'Facebook/FacebookAuthorizationException.php' );
require_once( 'Facebook/GraphObject.php' );
require_once( 'Facebook/GraphSessionInfo.php' );

use Facebook\HttpClients\FacebookHttpable;
use Facebook\HttpClients\FacebookCurl;
use Facebook\HttpClients\FacebookCurlHttpClient;

use Facebook\Entities\AccessToken;
use Facebook\Entities\SignedRequest;

use Facebook\FacebookSession;
use Facebook\FacebookRedirectLoginHelper;
use Facebook\FacebookRequest;
use Facebook\FacebookResponse;
use Facebook\FacebookSDKException;
use Facebook\FacebookRequestException;
use Facebook\FacebookOtherException;
use Facebook\FacebookAuthorizationException;
use Facebook\GraphObject;
use Facebook\GraphSessionInfo;

FacebookSession::setDefaultApplication('app_id', 'app_secret');

// If you already have a valid access token:
$session = new FacebookSession('access token'); 


// To validate the session:
try {
  $session->validate();
} catch (FacebookRequestException $ex) {
  // Session not valid, Graph API returned an exception with the reason.
  echo $ex->getMessage();
} catch (\Exception $ex) {
  // Graph API returned info, but it may mismatch the current app or have expired.
  echo $ex->getMessage();
}


try {
  $response = (new FacebookRequest($session, 'GET', '/me'))->execute();
  $object = $response->getGraphObject();
  echo $object->getProperty('name');
} catch (FacebookRequestException $ex) {
  echo $ex->getMessage();
} catch (\Exception $ex) {
  echo $ex->getMessage();
}

?>

I get my access token from this link :

https://graph.facebook.com/oauth/access_token?client_id={app-id} &client_secret={app-secret}&grant_type=client_credentials

When I execute the code I get this error :

An active access token must be used to query information about the current user.

What i'm doing wrong ? Thanks