将Session写入Memcache

通过session_set_save_handler()方法自定义Session写入Memcache

 <?php

     class MemSession{

         private static $handler = null;

         private static $lifetime = null;

         private static $time = null;

         const MS = 'session';

         private static function init($handler){

             self::$handler = $handler;

             self::$lifetime = ini_get('session.gc_maxlifetime');

             self::$time = time();

         }

         public static function start($memcache){

             self::init($memcache);

             //调用类中的方法要用数组,__CLASS__代表本类

             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){

         }

         public static function close(){

         }

         public static function read($PHPSESSID){

             $val = self::$handler->get(self::session_key($PHPSESSID));

             if($val===false || $val==null){

                 return false;

             }

             return $val;

         }

         public static function write($PHPSESSID,$data){

             $method = $data? 'set':'replace';

             return self::$handler->$method(self::session_key($PHPSESSID),$data,MEMCACHE_COMPRESSED,self::$lifetime);

         }

         public static function destroy($PHPSESSID){

             return self::$handle->delete(self::session_key($PHPSESSID));

         }

         //memcache本身就有限定时间，数据自动销毁，所以可不使用gc方法

         public static function gc($lifetime){

             return true;

         }

         //给sessionID加前缀，避免key重复

         private static function session_key($PHPSESSID){

             $session_key = self::MS.$PHPSESSID;

             return $session_key;

         }

     }

     $mem = new Memcache;

     $mem->connect("localhost",11211) or die("could not connect");

     MemSession::start($mem);