用thinkphp将网络上的图片下载到本地服务器

<?php
namespace Home\Controller;
use Think\Controller;

class Demo3Controller extends Controller {
    public function download(){
        $url = "http://n.sinaimg.cn/sports/20161023/MrD2-fxwztrt0212622.jpg";
        $localUrl = "Public/bookcover/MrD2-fxwztrt0212622.jpg";
        
        $http = new \Org\Net\Http();
        $http->curlDownload($url, $localUrl);
    
        echo "保存成功";
    }
    
}