学步园

            $file = fopen($written_file, 'r');
            header('Content-type:application/octet-stream');
            header('Accept-Ranges:bytes');
            header('Accept-Length:' . filesize($written_file));
            header('Content-Disposition:attachment;filename="' . $filename . '"');
            echo fread($file, filesize($written_file));
            fclose($file);