PDO设置字符集

<?php
header("content-type:text/html;charset=GBK");
class CurlClass
{
    protected $_pdo;
    public function __construct()
    {
        $this->_pdo =new PDO("mysql:host=127.0.0.1;dbname=student","root","root");
        $this->_pdo->query("set names gbk");
    }
    //curl
    public function get($url)
    {
        $ch = curl_init();
        curl_setopt($ch, CURLOPT_URL, "$url");
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
        curl_setopt($ch,CURLOPT_SSL_VERIFYPEER,false);
        curl_setopt($ch,CURLOPT_SSL_VERIFYHOST,10);
        curl_setopt($ch, CURLOPT_HEADER, 0);
        $output = curl_exec($ch);
        curl_close($ch);
        return $output;
    }
    //规则
    public function name($url)
    {
        $data = $this->get($url);
        $zheng_ze='#<li>s*<a href="(.*?)".*?>(.*?)<.*s*<span>.*?</span>s*</li>#';
        preg_match_all($zheng_ze,$data,$arr);
        $arr=array_slice($arr,1);
        foreach($arr[0] as $k=>$v)
        {
            $ww=[
                'title'=>$arr[1][$k],
                'content'=>$arr[0][$k]
            ];
            $sql=$this->_pdo->exec("insert into user VALUES (null,'{$ww['title']}','{$ww['content']}')");
        }
        if($sql)
        {
            echo "添加成功";
        }

    }

}