public function down()
    {
        $lang = strtolower(cookie(‘think_language‘));
        if ($lang == ‘en-us‘) {
            $filename = ‘1.pdf‘;
        } elseif ($lang == ‘es-us‘) {
//....
            $filename = ‘2.pdf‘;
        } else {
            $filename = ‘3.pdf‘;
}
        if (false === is_file($filename)) {
            exit(‘file does not exist‘);
        }
        // http headers
        header(‘Content-Type: application-x/force-download‘);
        header(‘Content-Disposition: attachment; filename="‘ . basename($filename) . ‘"‘);
        header(‘Content-length: ‘ . filesize($filename));
        // for IE6
        if (false === strpos($_SERVER[‘HTTP_USER_AGENT‘], ‘MSIE 6‘)) {
            header(‘Cache-Control: no-cache, must-revalidate‘);
        }
        header(‘Pragma: no-cache‘);
        // read file content and output
        return readfile($filename);
    }
原文:http://www.cnblogs.com/web21/p/6074635.html