对于大访问量的站点使用默认的Session 并不合适，我们可以将其存入数据库、或者使用Redis KEY-VALUE数据存储方案

首先新建一个session表

CREATE TABLE `sessions` (`sid` char(40) NOT NULL,`updatetime` int(20) NOT NULL,`data` varchar(200) NOT NULL,UNIQUE KEY `sid` (`sid`) USING HASH
) ENGINE=MEMORY DEFAULT CHARSET=utf8;

Mysql 的memory引擎采用内存表，所有数据存储在内存，操作速度快

<?php
//引入数据库文件
include "db.php";
class MySessionHandler implements SessionHandlerInterface
{private $savePath;private $sessData;public $expiretime;    //设置过期时间public $db; //数据库public function __construct($hanlder =''){$this->db = Database::getInstance();  //获取数据库实力 ///var_dump($this->db);}public function open($savePath, $sessionName){return true;}public function close(){return true;}public function read($id){    $sql ="select * from sessions where sid ='$id'";$result = $this->db->execute($sql);if(!empty($result)){return $this->sessData = $result;}}//函数的参数 $id -> 当前会话ID//数据DATA -> 序列化之后的字符串public function write($id, $data){// echo $id;// echo $data;$now = time();$newExp = $now+$this->expiretime;    //总时间=当前时间 + 期限时间$sql = "select * from sessions where sid ='$id'";$result = $this->db->getOne($sql);//var_dump($result);if($data==''||isset($data)){$data = $this->sessData;}if($result){//如果存在则更新$sql ="update sessions set updatetime = '$newExp',data ='$data' where sid = '$id'";//echo $sql;$update_data =$this->db->execute($sql);if($update_data){return true;}}else{//不存在则生成生成$sql = "insert into sessions(sid,updatetime,data) values('$id','$now','$data')";$insert_data = $this->db->execute($sql);if($insert_data){return true;}}return false;}public function destroy($id){        //销毁$sql = "delete from sessions where sid="."$id";$destory = $this->db->execute($sql);if($destory){return true;}else{return false;}}public function gc($sessMaxLifeTime){$t = time();$sql ="delete from sessions where $t - 'updatetime'>${sessMaxLifeTime}";$data = $this->db->execute($this->tosql);if($data){return true;}else{return false;}return true;}
}

实例化

此处 PHP 手册可以有两种方法

1，实现了SessionHandlerInterface借口的对象,自PHP5.4可以使用

2 ，直接使用  session_set_save_handler

 //判断PHP版本if(version_compare(PHP_VERSION,5.4)==1){session_set_save_handler($handler, true);session_start();}else{     ini_set('session.use_trans_sid',0);ini_set('session.use_cookies',1);ini_set('session.cookie_path','/');ini_set('session.save_handler','user');session_module_name('user');session_set_save_handler(array($session,"open"),array($session,"close"),array($session,"read"),array($session,"write"),array($session,"destory"),array($session,"gc"));session_start();     }
$_SESSION['QQ']="QQ";
echo $_SESSION['QQ'];

数据库代码

<?php
class Database{static $instance;static $db;static  function getInstance(){      if(self::$instance){return self::$instance;}else{return new  Database();   }}public function __construct(){self::$db = new PDO('mysql:host=localhost;dbname=session', 'root','');}public  function getOne($sql){$rs =self::$db->query($sql);@$rs->setFetchMode(PDO::FETCH_ASSOC);//返回关联数组$result = $rs -> fetch();return $result;}public function execute($sql){$rs = self::$db->exec($sql);return $rs;} }//$data = Database::getInstance();
//var_dump($data);

使用REDIS 存储SESSION

<?php
class SessionManager{private $redis;private $sessionSavePath;private $sessionName;private $sessionExpireTime = 30;public function __construct(){$this->redis = new Redis();$this->redis->connect('127.0.0.1',6379);    //连接redis$retval = session_set_save_handler(array($this,"open"),array($this,"close"),array($this,"read"),array($this,"write"),array($this,"destory"),array($this,"gc"));session_start();}public function open($path,$name){return true;}public function close(){return true;}public function read($id){$value = $this->redis->get($id);if($value){return $value;}else{return "";}}public function write($id,$data){if($this->redis->set($id,$data)){$this->redis->expire($id,$this->sessionExpireTime);  //设置过期时间return true;}return false;}public function destory($id){if($this->redis->delete($id)){return true;}return false;}public function gc($maxlifetime){return true;}//析构函数public function __destruct(){session_write_close();}}$re = new SessionManager();
$_SESSION['name'] = "qq";
echo $_SESSION['name'];