/** * Session类简单实现 * @author zhjx922 */class Session{    //当前sessionId    private $_sessionId;    //session的储存路径    private $_sessionPath = '/tmp/session';    /**     * 初始化sessionId     */    public function __construct()    {        if(isset($_COOKIE['PHPSESSID']) && $this->checkSession($_COOKIE['PHPSESSID'])) {            $this->_sessionId = $_COOKIE['PHPSESSID'];        } else {            $this->_sessionId = uniqid();            setcookie("PHPSESSID", $this->_sessionId);        }    }    /**     * 设置session     * @param string $key     * @param mixed $value     */    public function setSession($key, $value)    {        $sessionInfo = $this->getSessionInfo();        $sessionInfo[$key] = $value;        $sessionFile =  "{$this->_sessionPath}/{$this->_sessionId}";        file_put_contents($sessionFile, serialize($sessionInfo));    }    /**     * 获取session     * @param string $key     * @return mixed     */    public function getSession($key)    {        return $this->getSessionInfo()[$key];    }    /**     * 获取当前sessionId下的内容     * @return array     */    private function getSessionInfo()    {        if(!is_dir($this->_sessionPath))        {            mkdir($this->_sessionPath);        }        $sessionFile =  "{$this->_sessionPath}/{$this->_sessionId}";        if(is_file($sessionFile)) {            $contents = file_get_contents($sessionFile);            return unserialize($contents);        }        return [];    }    /**     * 检查session是否有效     * @param string $sessionId     * @return bool     */    private function checkSession($sessionId)    {        $sessionFile =  "{$this->_sessionPath}/{$sessionId}";        if(is_file($sessionFile)) {            return true;        }        return false;    }}

使用方法如下

$session = new Session();$session->setSession('a', 'b'); //第二次访问时注释掉这行，验证下一行$session->getSession('a')输出的内容是否正确var_dump($session->getSession('a'));