/**
 * Session類簡單實現(xiàn)
 * @author zhjx922
 */
class Session
{
    //當前sessionId
    private $_sessionId;
    //session的儲存路徑
    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);
        }
    }

    /**
     * 設(shè)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));
    }

    /**
     * 獲取session
     * @param string $key
     * @return mixed
     */
    public function getSession($key)
    {
        return $this->getSessionInfo()[$key];
    }

    /**
     * 獲取當前sessionId下的內(nèi)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 [];
    }

    /**
     * 檢查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();
$session->setSession('a', 'b'); //第二次訪問時注釋掉這行，驗證下一行$session->getSession('a')輸出的內(nèi)容是否正確
var_dump($session->getSession('a'));