如何用 PHP 获取目录大小

function GetDirectorySize($path){
    $bytestotal = 0;
    $path = realpath($path);
    if($path!==false && $path!='' && file_exists($path)){
        foreach(new RecursiveIteratorIterator(new RecursiveDirectoryIterator($path, FilesystemIterator::SKIP_DOTS)) as $object){
            $bytestotal += $object->getSize();
        }
    }
    return $bytestotal;
}