php 实现文件下载，兼容IE、Firefox、Chrome等浏览器

　　　　 Header("Content-type: application/octet-stream");
        $ua = $_SERVER["HTTP_USER_AGENT"];
        $encoded_filename = rawurlencode($filename);
        if (preg_match("/MSIE/", $ua)) {
            header(‘Content-Disposition: attachment; filename="‘ . $encoded_filename . ‘"‘);
        } else if (preg_match("/Firefox/", $ua)) {
            header("Content-Disposition: attachment; filename*=\"utf8‘‘" . $filename . ‘"‘);
        } else {
            header(‘Content-Disposition: attachment; filename="‘ . $filename . ‘"‘);
        }
        $file = ‘xxxx.pdf‘;
        header("Content-Length: ". filesize("{$file}"));

　　　　 ...
        $objWriter = PHPExcel_IOFactory::createWriter($objPHPExcel, ‘Excel5‘);
        header(‘Content-Type: application/vnd.ms-excel‘);
        $ua = $_SERVER["HTTP_USER_AGENT"];
        $encoded_filename = rawurlencode($filename);
        if (preg_match("/MSIE/", $ua)) {
            header(‘Content-Disposition: attachment; filename="‘ . $encoded_filename . ‘"‘);
        } else if (preg_match("/Firefox/", $ua)) {
            header("Content-Disposition: attachment; filename*=\"utf8‘‘" . $filename . ‘"‘);
        } else {
            header(‘Content-Disposition: attachment; filename="‘ . $filename . ‘"‘);
        }
        header(‘Cache-Control: max-age=0‘);
        $objWriter->save(‘php://output‘);