if (!function_exists('output_for_download')) {    /**     * 下载文件到浏览器     *     * @param string $filename 文件路径     * @param array  $title    输出的文件名     * @return void     */    function output_for_download($filename, $title)    {        $file  =  fopen($filename, "rb");        Header( "Content-type:  application/octet-stream ");        Header( "Accept-Ranges:  bytes ");        Header( "Content-Disposition:  attachment;  filename= $title");        while (!feof($file)) {            echo fread($file, 8192);            ob_flush();            flush();        }        fclose($file);    }}复制代码