function clear_file()
{
    if (file_exists(STORAGE_TARGET)) {
        $log = unlink(STORAGE_TARGET) ? 'ZIP delete SUCCESS.' : 'ZIP delete FAIL.';
        access_log('log', $log);
    }
    $current_path = dirname(__FILE__);
    $extract_file = $current_path . '/upload/test.txt';
    if (file_exists($extract_file)) {
        $log = unlink($extract_file) ? 'TXT delete SUCCESS.' : 'TXT delete FAIL.';
        access_log('log', $log);
    }
}
 /**
  * 日志
  * @param type $info
  */
 private function _log($info)
 {
     access_log('FTP', $info);
 }