PHP 實現 Session 存入資料庫完整類庫

使用 session_set_save_handler() 將 Session 數據寫入 MySQL 資料庫。資料庫名 session，表名 session，欄位：PHPSESSID, update_time, client_ip, data。

<?php
class Session {
    private static $handler = null;
    private static $ip = null;
    private static $lifetime = null;
    private static $time = null;

    private static function init($handler) {
        self::$handler = $handler;
        self::$ip = !empty($_SERVER["REMOTE_ADDR"]) ? $_SERVER["REMOTE_ADDR"] : 'unknown';
        self::$lifetime = ini_get('session.gc_maxlifetime');
        self::$time = time();
    }

    static function start($pdo) {
        self::init($pdo);
        session_set_save_handler(
            array(__CLASS__, 'open'),
            array(__CLASS__, 'close'),
            array(__CLASS__, 'read'),
            array(__CLASS__, 'write'),
            array(__CLASS__, 'destroy'),
            array(__CLASS__, 'gc')
        );
        session_start();
    }

    public static function open($path, $name) { return true; }
    public static function close() { return true; }

    // 讀取 Session
    public static function read($PHPSESSID) {
        $sql = "select PHPSESSID,update_time,client_ip,data from session where PHPSESSID=?";
        $stmt = self::$handler->prepare($sql);
        $stmt->execute(array($PHPSESSID));
        if(!$result = $stmt->fetch(PDO::FETCH_ASSOC)) return '';
        if(self::$ip == $result['client_ip']) { self::destroy($PHPSESSID); return ''; }
        if(($result['update_time']+self::$lifetime) < self::$time) { self::destroy($PHPSESSID); return ''; }
        return $result['data'];
    }

    // 寫入/更新 Session
    public static function write($PHPSESSID, $data) {
        $sql = "select PHPSESSID,update_time,client_ip,data from session where PHPSESSID=?";
        $stmt = self::$handler->prepare($sql);
        $stmt->execute(array($PHPSESSID));
        if($result=$stmt->fetch(PDO::FETCH_ASSOC)) {
            if($result['data'] != $data || self::$time > ($result['update_time']+30)) {
                $sql = "update session set update_time=?,data=? where PHPSESSID = ?";
                $stmt = self::$handler->prepare($sql);
                $stmt->execute(array(self::$time, $data, $PHPSESSID));
            }
        } else {
            if(!empty($data)) {
                $sql = "insert into session(PHPSESSID,update_time,client_ip,data) values(?,?,?,?)";
                $sth = self::$handler->prepare($sql);
                $sth->execute(array($PHPSESSID, self::$time, self::$ip, $data));
            }
        }
        return true;
    }

    public static function destroy($PHPSESSID) {
        $sql = "delete from session where PHPSESSID = ?";
        $stmt = self::$handler->prepare($sql);
        $stmt->execute(array($PHPSESSID));
        return true;
    }

    public static function gc($lifetime) {
        $sql = "delete from session where update_time<?";
        $stmt = self::$handler->prepare($sql);
        $stmt->execute(array(self::$time-$lifetime));
        return true;
    }
}

// 使用 PDO 連接並啟動
try {
    $pdo = new PDO("mysql:host=localhost;dbname=session","root","hwj193");
} catch(PDOException $e) {
    echo $e->getMessage();
}
Session::start($pdo);