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详解mysql操作sessions机制

发布时间：2017-04-14 11:18:57编辑：雪饮阅读（）

 回顾魔术方法-自动载入：

function __autoload($classname){

include $ classname.".class.php";

}

如在当前页面new一个类的时候该类并不存在于当前页面，那么就会以这个类名自动载入这个类的文件

 

注册类里面的一个函数为自动载入的魔术方法：

class App{

static function autoload($classname){

/*

因为注册时穿参是用类直接调用该方法，所以是静态调用

*/

require_once $ classname.".class.php";

}

}

spl_autoload_register(array("App","autoload"));

 

 

sessionID是一个md5字串

 

建立用于存储session的数据表：

create table session(sid char(32),data varchar(255),mtime int(10),ip char(15),card char(32)) engine = myisam default charset=gbk;

 

当php配置文件中将session垃圾判定时间该为1秒时，且垃圾处理机制的几率是100%则会执行两次垃圾处理机制。

 

 

session入库脚本示例：

<?php

/**

 * 后盾网  http://www.houdunwang.com

 * 2011-6-21 上午11:03:48

 */

 

class session{

         //数据库操作句柄

         static $db;

         //SESSION表

         static $table;

         //SESSION过期时间

         static $max_time;

         //客户端身份信息

         static $card;

         //SESSION初始化

         static function run(){

                   if(ini_get("session.save_handler") == "user" || ini_set("session.save_handler", "user")){

                            session_set_save_handler(

                                     array(__CLASS__,"start"),

                                     array(__CLASS__,"close"),

                                     array(__CLASS__,"read"),

                                     array(__CLASS__,"write"),

                                     array(__CLASS__,"destroy"),

                                     array(__CLASS__,"gc"));

                                     ob_start();

                                     self::$db = new mysqli("localhost","root","","edu");

                                     !mysqli_connect_errno() or die("数据库连接错误");

                                     self::$db->query("SET NAMES GBK");

                                     self::$table="session";

                                     self::$max_time = 600;

                                     self::$card = md5($_SERVER['REMOTE_ADDR'].$_SERVER['HTTP_USER_AGENT']);

                                     session_start();                                   

                   }

         }

         static function start($path,$session_name){

                   return true;

         }

         static function close(){

                   self::gc(self::$max_time);

                   self::$db->close();

                   return true;

         }

         static function read($sid){

                   $sql  = "SELECT `data` FROM ".self::$table." WHERE `sid` ='{$sid}' AND `card`='".self::$card."'";

                   $result = self::$db->query($sql);

                   $row = $result->fetch_assoc();

                   return self::$db->affected_rows>0?$row['data']:'';

         }

         static function write($sid,$data){

                   $sql  = "SELECT `sid` FROM ".self::$table." WHERE `sid` ='{$sid}' AND `card`='".self::$card."'";        

                   $result = self::$db->query($sql);

                   $mtime = time();

                   if(self::$db->affected_rows>0){

                            $sql = "UPDATE ".self::$table." SET `data` ='{$data}',`mtime` ='{$mtime}'

                                 WHERE `sid`='{$sid}'";           

                   }else{

                            $sql = "INSERT INTO ".self::$table." (`sid`,`data`,`mtime`,`ip`,`card`) VALUES('{$sid}','{$data}','".time()."','{$_SERVER['REMOTE_ADDR']}','".self::$card."')";

                   }

                   return self::$db->query($sql)?true:false;

         }

         static function destroy($sid){

                   $sql = "DELETE FROM ".self::$table." WHERE `sid`='{$sid}'";

                   self::$db->query($sql);

                   return true;

         }

         static function gc($max_time){

                   $max_time = self::$max_time;

                   $sql = "DELETE FROM ".self::$table." WHERE `mtime`<'".(time()-$max_time)."'";

                   self::$db->query($sql);

                   return true;

         }

}

session::run();