PHP递归删除目录及目录下的文件

public function del_cache( $dirName=RUNTIME_PATH ){
//$dirName =RUNTIME_PATH ;//runtime目录
if($handle = opendir($dirName)){
while ($item = readdir( $handle )) {
# 去..及.
if($item != '.' && $item != '..'){
if(is_dir($dirName.$item)){
//是目录
// print_r($dirName.$item);
$this->del_cache($dirName.$item.DS);
}else{

$result = unlink($dirName.$item);
}
}

}
}
echo "清理缓存成功!"."<br />";

}