我最终自己解决了这个问题，但得到了@Bainternet的帮助（检查帖子内容中是否存在短代码）。

我所做的是在我的类中创建一个变量，名为facebook, 我在这里存储PHP SDK类。我用了wp 钩子来启动Facebook类如果一些事情设置正确，这个钩子允许我使用global $post 这样我就可以抓住元值。

require \'facebook.php\';
$urgent = JW_Urgent::getInstance();

class JW_Urgent {

    private static $instance;
    public $facebook;

    // Construct the class\' data
    private function __construct() {

        $this->facebook = null;

        add_action( \'wp\', array( &$this, \'define_facebook\' ) );
        add_shortcode( \'jw-connect\', array( &$this, \'fb_connect_shortcode\' ) );

    }

    public static function getInstance() {
        if ( is_null( self::$instance ) )
            self::$instance = new JW_Urgent();

        return self::$instance;
    }


    public function define_facebook() {
        global $post;

        $app_id = get_post_meta( $post->ID, $this->meta_prefix . \'AppID\', true );
        $app_secret = get_post_meta( $post->ID, $this->meta_prefix . \'AppSecret\', true );

        if( !is_null( $post ) && ( $app_id !== \'\' && $app_secret !== \'\' ) && $post->post_type == $this->post_type ) {

            if( strpos( $post->post_content, \'[jw-connect\' ) !== false ) {

                $this->facebook = new Facebook( array(
                    \'appId\' => $app_id,
                    \'secret\' => $app_secret
                ) );

            }

        }

    }

    public function fb_connect_shortcode( $atts, $content = null ) {
        extract( shortcode_atts( array( ), $atts ) ); /**/ global $post;
        $app_id = get_post_meta( $post->ID, $this->meta_prefix . \'AppID\', true );
        $app_secret = get_post_meta( $post->ID, $this->meta_prefix . \'AppSecret\', true );

        if( $app_id !== \'\' && $app_secret !== \'\' && !is_null( $this->facebook ) ) {

            // See if there is a user from a cookie
            $user = $this->facebook->getUser();

            if( $user ) {
                try {
                    // Proceed knowing you have a logged in user who\'s authenticated.
                    $user_profile = $this->facebook->api( \'/me\' );
                    $app_id = $this->facebook->getAppId();
                } catch( FacebookApiException $e ) {
                    echo \'<pre>\' . htmlspecialchars( print_r( $e, true ) ) . \'</pre>\';
                    $user = null;
                }
            }

            wp_enqueue_script( \'jw-fbsdk\', plugins_url( \'jw-fbsdk.js\', __FILE__ ), array(), \'3.3.1\', true );
            wp_localize_script( \'jw-fbsdk\', \'jwuc\', array(
                \'appId\' => $app_id,
                \'channelUrl\' => plugins_url( \'channel.php\', __FILE__ )
            ) );

            if( is_null( $content ) )
                $content = \'Connect with Facebook\';

            if( isset( $user_profile ) && $user_profile ) {
                return $user_profile[\'name\'];
            } else {
                return \'<div class="fb-login-button" data-scope="email,publish_stream,read_stream,status_update">\' . $content . \'</div>\';
            }

        } else {

            return "You forgot to add your App ID and/or App Secret! Facebook needs these. :)";

        }

    }

}