020.CI4框架CodeIgniter, 关于session的创建，删除和读取

01.在BaseController.php中添加一下代码，如图所示

$this->session = \Config\Services::session();

02.在Home.php文件中，写入session的创建如下代码：

<?php namespace App\Controllers;

class Home extends BaseController
{

    function __construct()
    {

    }

    // http://127.0.0.1/CI4/public/index.php/home/getsession
    //设置session
    public function setsession()
    {
        //设置session
        $data = array(
            'username' => '田攀',
            'password' => '青青子衿悠悠我心',
        );
        $this->session->set($data);

        // 有效性只有5秒
        $this->session->setTempdata('user', '张三', 5);
    }

    //删除session
    public function removesession()
    {
        //输出session
        $this->session->remove('username');
    }

    //取session子
    public function getsession()
    {
        //输出session
        ShowMessage($this->session->username);
        //输出session
        ShowMessage($this->session->getTempdata('user'));
        //输出没有的session
        ShowMessage($this->session->user);
        //判断是否有session
        ShowMessage($this->session->has('user'));
        //判断是否有session
        ShowMessage($this->session->has('username'));
    }
}