php实现将Session写入数据库


            使用session_set_save_handler()函数，将Session的内容写入数据库





<?php

  /*

  *@author  Fahy

  *数据库为mysql，

  *数据库名为session，表名为session，

  *表中字段包括PHPSESSID,update_time,client_ip,data

  */

  class Session{

    private static $handler = null;

    private static $ip = null;

    private static $lifetime = null;

    private static $time = null;

    

    //配置静态变量

    private static function init($handler){

      self::$handler = $handler;    //获取数据库资源

      self::$ip = !empty($_SERVER["REMOTE_ADDR"])? $_SERVER["REMOTE_ADDR"]:'unkonw';    //获取客户端ip

      self::$lifetime = ini_get('session.gc_maxlifetime');    //获取session生命周期

      self::$time = time();    //获取当前时间

    }

    //调用session_set_save_handler()函数并开启session

    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;

    }

    

    //查询数据库中的数据

    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'];

    }

    /*

    *首先查询该session是否存在数据，如果存在，则更新数据，如果不存在，则插入数据

    */

    //将session写入数据库中，$data传入session中的keys和values数组

    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)){

          try{

            $sql = "insert into session(PHPSESSID,update_time,client_ip,data) values(?,?,?,?)";

          }catch(PDOException $e){

            echo $e->getMessage();

          }

          $sth = self::$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连接数据库

  try{

    $pdo = new PDO("mysql:host=localhost;dbname=session","root","hwj193");

  }catch(PDOException $e){

    echo $e->getMessage();

  }

  //传递数据库资源

  Session::start($pdo);







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