TP5怎么生成XML地图

    public function xml()
    {
        $request = Request::instance();
        $url = $request->domain();//获取当前请求域名
        $res = Db::name('data')->order('id desc')->select();
        $html = '';
        $html .= '<urlset>';
        foreach ($res as $key => $value) {
            $create_time=date('Y-m-s',$value['create_time']);
            $html .= '<url>';
            $html .= '<loc>'.$url.'/'. $value['id'] . '.html</loc>';
            $html .= ' <lastmod>' . $create_time. '</lastmod>';
            $html .= ' <changefreq>Always</changefreq>';
            $html .= '  <priority>0.8</priority>';
            $html .= '</url>';
        }
        $html .= '</urlset>';
        return xml([$html,200,[],['root_node'=>'xml']]);
    }