php实现Session存储到Redis

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'];