session数据库类

<?php
/**
 * session类
 * @author 角度 QQ:1286522207
 *
 */
class session extends Action{
	private $session_db;
	private $session_Overdue;
	private $db_tablename;//数据库名称
	function __construct(){
		$this->session_Overdue=3600;
		$this->session_db= $this->db();
	}
	/**
	 * 打开
	 */
	public function open() {
		return true;
	}
	/**
	 * 关闭
	 */
	public function close() {
		return true;
	}
	/**
	 * 读取
	 */
	public function read($id) {
		$where['id']=$id;
		$this->session_db->M('session');
		$value=$this->session_db->find($where);
		if ($value) {
			return $value['data'];
		} else {
			return "";
		}
	}
	/**
	 * 写入
	 */
	public function write($id, $datas) {
		$where['id']=$id;
		$date['data']=$datas;
		$date['time']=time()+$this->session_Overdue;
		$date['ip']=$this->session_db->get_client_ip();
		if (empty($_SESSION['user_id'])){
			$date['user']=0;
		}else {
			$date['user']=$_SESSION['user_id'];
		}
		$this->session_db->M('session');
		$up=$this->session_db->Update($date, $where);
		if ($up){
			return true;
		}else {
			$date['id']=$id;
			$this->session_db->Insert($date);
			return true;
		}
	}
	/**
	 * 摧毁
	 */
	public function destroy($id) {
		$where['id']=$id;
		return $this->session_db->Delete($where);
	}
	/**
	 * 回收
	 */
	public function gc($max) {
		return true;
	}
	function __destruct(){
		$this->session_db->Delete("`time`<'".time()."'");
	}
}
ini_set ( 'session.save_handler',$config['SESSION_START']);
$session = new session ();
session_set_save_handler ( array ($session, 'open' ), array ($session, 'close' ), array ($session, 'read' ), array ($session, 'write' ), array ($session, 'destroy' ), array ($session, 'gc' ) );
session_start();