第一步:引导用户打开如下链接 (详细介绍见OAuth2.0)

$url = urlencode('http://xxx.com/xxx');
$newurl = "https://open.weixin.qq.com/connect/oauth2/authorize?appid=wx9c807c944920c501&redirect_uri=$url&response_type=code&scope=snsapi_base&state=123#wechat_redirect";

注意这里需要去配置redirect_uri 回调URL的授权域名
如果用户同意授权，页面将跳转至 redirect_uri/?code=CODE&state=STATE。若用户禁止授权，则重定向后不会带上code参数，仅会带上state参数redirect_uri?state=STATE

点击修改

第二步:封装拉取用户信息类

public function Oauth($code='',$mode=0){
    $appid = $this->AppId ;  //公共账号 appid
    $secret = $this->AppSecret ;  //公众账号AppSecret 
    if($code=='') $code = $_REQUEST['code'] ; //接收参数
    if(!$code) return false ;
    $cul = 'https://api.weixin.qq.com/sns/oauth2/access_token?appid='.$appid.'&secret='.$secret.'&code='.$code.'&grant_type=authorization_code' ;
    $cx = file_get_contents($cul) ;
    $bx = json_decode($cx,true) ;
    if($bx['errcode']){
        //第一步 根据code获取refresh_token
        $this->restat = 0 ;
        $this->errmsg = $bx ;  return  ;
    }
    $rtoken = $bx['refresh_token'] ;
    $rurl = 'https://api.weixin.qq.com/sns/oauth2/refresh_token?appid='.$appid.'&grant_type=refresh_token&refresh_token='.$rtoken ;
    $rr = file_get_contents($rurl) ;
    $rr = json_decode($rr,true) ;
    if($rr['errcode']){
        //第二步 根据refresh_token获取的access_token和openid
        $this->restat = 0 ;
        $this->errmsg = $bx ;  return  ;
    }
    $acct = $rr['access_token'] ;
    //file_put_contents('abc.txt', $acct);
    $this->auth_access_token = $acct ; //存放认证的token

    $openid = $rr['openid'] ;
    if($mode == 0 ) return  ;
    //第三步拉取信息
    $purl = "https://api.weixin.qq.com/sns/userinfo?access_token=$acct&openid=$openid&lang=zh_CN" ;
    $xv = file_get_contents($purl) ;
    //file_put_contents('xv.txt', $xv);
    /*$xv返回数据格式
        {"openid":"XXX","nickname":"Mini_Ren","sex":1,"language":"zh_CN","city":"郑州","province":"河南","country":"中国","headimgurl":"","privilege":[]}
    */
    $xv = json_decode($xv,true) ;
    if($xv['errcode']){
        $this->restat = 0 ;
        $this->errmsg = $bx ;  return  ;
    }
    $this->res = $xv ;
    return $xv ; //带有用户信息数组
}

PS:微信Oauth认证类下载 Oauth认证下载