FACEBOOK SDK 4.0.0 FOR PHP: A WORKING SAMPLE TO GET STARTED

fb_sdk_4_Login_and_GetUserName.php

<?php
    session_start();
     
    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/FacebookAuthorizationException.php' );
    require_once( 'Facebook/GraphObject.php' );
     
    use Facebook\FacebookSession;
    use Facebook\FacebookRedirectLoginHelper;
    use Facebook\FacebookRequest;
    use Facebook\FacebookResponse;
    use Facebook\FacebookSDKException;
    use Facebook\FacebookRequestException;
    use Facebook\FacebookAuthorizationException;
    use Facebook\GraphObject;
     
    // init app with app id (APPID) and secret (SECRET)
    FacebookSession::setDefaultApplication('APPID','SECRET');
     
    // login helper with redirect_uri
    $helper = new FacebookRedirectLoginHelper( 'http://localhost/fb4/pic.php' );
     
    try {
     	$session = $helper->getSessionFromRedirect();
    } catch( FacebookRequestException $ex ) {
      	// When Facebook returns an error
    } catch( Exception $ex ) {
      	// When validation fails or other local issues
    }
     
    // see if we have a session
    if (isset($session)) {
      	// graph api request for user data
      	$request = new FacebookRequest( $session, 'GET', '/me' );
      	$response = $request->execute();
      	// get response
      	$graphObject = $response->getGraphObject();
       
      	// print data
      	echo  print_r( $graphObject, 1 );
    } else {
      	// show login url
      	echo '<a href="' . $helper->getLoginUrl() . '">Login</a>';
    }





?>