public static function getAppPath()
 {
     if (!isset(self::$_app_path)) {
         $app = self::getApp();
         $path = self::getPath();
         if (count($path)) {
             self::$_app_path = '/' . $app . '/' . join('/', $path);
         } else {
             self::$_app_path = $app;
         }
     }
     return self::$_app_path;
 }