首先获取微信公众号的appID和secret

点击先获取code，用code去拿access_token

然后在用access_token去获取用户信息

在存用户信息到数据库

这里拿需要检测一下用户是否关注公众号

PHP

public function index(){
//        $id = $this->request->param('id');
        $appid = 'wxc8cdb6991cff2fca';
        $secret = '3d0e67625628d5d75f9dfd3f7ffcad81';

        if(!session('?userinfo')){
            if (!isset($_GET['code'])){//没有code，去微信接口获取code码
                $request = request();
                $callback = $request->url(true);//微信服务器回调url，这里是本页url
//                $this->get_code($callback);
                $redirect_uri=urlencode($callback);
                $url='https://open.weixin.qq.com/connect/oauth2/authorize?appid='.$appid.'&redirect_uri='.$redirect_uri.'&response_type=code&scope=snsapi_userinfo&state=1#wechat_redirect';
                header("location:$url");exit();


            } else {//获取code后跳转回来到这里了
                $code = $_GET['code'];
                $data = $this->get_access_token($code);//获取网页授权access_token和用户openid
                $data_all = $this->get_user_info($data['access_token'],$data['openid']);//获取微信用户信息
                session('userinfo',$data_all);
                $this->checkuser($data_all['openid'],$data_all);
//                return json($data_all);
                $user_id = Db::name('user')->where('openid',$data_all['openid'])->find();
                    if($user_id){
                        Session::set('user_id',$user_id['id']);
                        $this->redirect('index/index/user');
                    }else{
                        echo'';
                    }

            }
        }else{
            $ret=session('userinfo');
//            var_dump($ret);die();
            return json($ret);             //返回的获取到的微信用户信息
        }
    }

    /**
     * 3、使用code换取access_token
     * @param string 用于换取access_token的code，微信提供
     * @return array access_token和用户openid数组
     */
    private function get_access_token($code){
//        $appid = config('appid');
//        $appsecret = config('secret');
//        $appid = 'wx65ac021e2de709df';
//        $appsecret = '806e5a9f22135c58d69975336e801a88';
        $appid = 'wxc8cdb6991cff2fca';
        $appsecret = '3d0e67625628d5d75f9dfd3f7ffcad81';

        $url = 'https://api.weixin.qq.com/sns/oauth2/access_token?appid=' . $appid . '&secret=' . $appsecret . '&code=' . $code . '&grant_type=authorization_code';
//        var_dump($url);die();
        $user = json_decode(file_get_contents($url));
        if (isset($user->errcode)) {
            echo 'error:' . $user->errcode.'
msg  :' . $user->errmsg;exit;
        }
        $data = json_decode(json_encode($user),true);//返回的json数组转换成array数组
        return $data;
    }

    /**
     * 4、使用access_token获取用户信息
     * @param string access_token
     * @param string 用户的openid
     * @return array 用户信息数组
     */
    private function get_user_info($access_token,$openid){
        $url = 'https://api.weixin.qq.com/sns/userinfo?access_token=' . $access_token . '&openid=' . $openid . '&lang=zh_CN';
        $user = json_decode(file_get_contents($url));
        if (isset($user->errcode)) {
            echo 'error:' . $user->errcode.'
msg  :' . $user->errmsg;exit;
        }
        $data = json_decode(json_encode($user),true);//返回的json数组转换成array数组
        return $data;
    }

    /**
     * 检查用户信息
     * TODO 在这个地方如果在用户表加一个时间字段，就可以每隔多少次对数据库进行一次操作，而不是一直更新操作。
     */
    public function checkuser($openid,$data){
        $check=Db::name('user')->where(array('openid'=>$openid))->find();
        if($check){
            /*更新用户信息*/
            $updata=array();
            $updata['image']=$data['headimgurl'];
            $updata['create_time']=time();
            $updata['username']=$data['nickname'];
            Db::name('user')->where('openid',$openid)->update($updata);

            /*获取最新用户信息并存入缓存*/
            $newinfo=Db::name('user')->where(array('id'=>$check['id']))->find();
            session('userinfo',$newinfo);

        }else{
            /*新增用户信息*/
            $intdata=array();
            $intdata = ['username' =>$data['nickname'], 'image' => $data['headimgurl'],'create_time'=>time(),'openid' => $data['openid'],'sex' => $data['sex'],'city' => $data['city'],'province' => $data['province'],'county' => $data['country']];
            Db::name('user')->insert($intdata);
            $userId = Db::name('user')->getLastInsID();
            /*获取最新用户信息并存入缓存*/
            if(!session('?userinfo')){
                $newinfo=Db::name('user')->where(array('id'=>$userId))->find();
//                $newinfo=Db::name('wxuser')->where('id',$userId)->find();array('openid'=>$openid,'delstatus'=>1)
                session('userinfo',$newinfo);
            }
        }
    }

检测是否关注公众号

/*↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓*/
    /*检测是否关注公众号*/
    /*subscribe    用户是否订阅该公众号标识，值为0时，代表此用户没有关注该公众号，拉取不到其余信息。*/
    /*https://www.cnblogs.com/mracale/p/9318349.html*/
    public function checkisgz(){
        $request = request();
        $callback = $request->url(true);//微信服务器回调url，这里是本页url

//        $appid = 'wxd25f887839ae5f30';
//        $secret = '71961adca3a8013a2791dc044fbf9439';
        $appid = 'wxc8cdb6991cff2fca';
        $secret = '3d0e67625628d5d75f9dfd3f7ffcad81';

        //微信网页授权获取openid
        $web_url=$callback;

        if (!isset($_GET['code'])) {
            $redirect_uri=urlencode($web_url);
            $url='https://open.weixin.qq.com/connect/oauth2/authorize?appid='.$appid.'&redirect_uri='.$redirect_uri.'&response_type=code&scope=snsapi_base&state=1#wechat_redirect';
            header("location:$url");exit();
        }
        $code=trim($_GET['code']);
        $url='https://api.weixin.qq.com/sns/oauth2/access_token?appid='.$appid.'&secret='.$secret.'&code='.$code.'&grant_type=authorization_code';
        $access=file_get_contents($url);
        $data=json_decode($access,true);
        $access_token=$data['access_token'];
        $url='https://api.weixin.qq.com/sns/userinfo?access_token='.$access_token.'&openid=OPENID&lang=zh_CN';
        $user=file_get_contents($url);
        $arr=json_decode($user,true);
        //获取用户的openid
        $openid=$arr['openid'];

        $url="https://api.weixin.qq.com/cgi-bin/token?grant_type=client_credential&appid=".$appid."&secret=".$secret;
        $access=file_get_contents($url);
        $access_arr=json_decode($access,true);
        //非网页的access_token
        $access_token=$access_arr['access_token'];

        $url="https://api.weixin.qq.com/cgi-bin/user/info?access_token=".$access_token."&openid=".$openid."&lang=zh_CN";
        $res=file_get_contents($url);
//                var_dump($res);die();
        return $res['subscribe'];
    }

HTML

点击去指向index方法获取code

<script>
    layui.use(['layer','upload', 'element'],function() {
        var form = layui.form;
        var layer = layui.layer;

        $('#SubmitAdd').click(function(){
            var index=layer.load();
            // var phone = $('#phone').val();
            // var password = $('#password').val();
            var id= 1;
            $.ajax({
                url:"{:url('index/Wxgetuserinfo/index')}",
                type:'get',
                data:{id:id},
                dataType:'json',
                success:function(res) {
                    layer.close(index);
                    console.log(res);
                    if ( res.code == 1 ) {
                        layer.msg(''+res.msg+'');
                        setTimeout(function(){
                            location.href=res.url;
                        },2000)
                    }else{
                        layer.msg(''+res.msg+'');
                    }
                }
            });
            return false;
        });


    })

script>

中间参数正确，待用户同意授权的，存用户信息，存Session

进行其他操作