thinkphp 判断登录

<?php
namespace app\index\controller;

use think\Controller;
use think\Request;

class Login extends Controller
{
    public function index()
    {
        return $this->fetch();
    }

    public function doLogin(Request $request)
    {
        $username = $request->param('username');
        $password = $request->param('password');

        // 假设这里是验证用户名和密码的逻辑
        if ($username === 'admin' && $password === '123456') {
            // 设置 Session
            session('user_id', 1);
            session('username', $username);
            return json(['code' => 200, 'msg' => '登录成功']);
        } else {
            return json(['code' => 400, 'msg' => '用户名或密码错误']);
        }
    }

    public function checkLogin()
    {
        if (session('?user_id')) {
            return json(['code' => 200, 'msg' => '已登录', 'user_id' => session('user_id')]);
        } else {
            return json(['code' => 400, 'msg' => '未登录']);
        }
    }
}