<?php
class Session_custom {
  private $redis; // redis實(shí)例
  private $prefix = 'sess_'; // session_id前綴
  
  // 會(huì)話開(kāi)始時(shí)，會(huì)執(zhí)行該方法，連接redis服務(wù)器
  public function open($path, $name) {
    $this->redis = new Redis();
    return $this->redis->connect("127.0.0.1",6379);
  }
  
  // 會(huì)話結(jié)束時(shí)，調(diào)用該方法，關(guān)閉redis連接
  public function close() {
    $this->redis->close();
    return true;
  }
  
  // 會(huì)話保存數(shù)據(jù)時(shí)調(diào)用該方法，在腳本執(zhí)行完或session_write_close方法調(diào)用之后調(diào)用
  public function write($session_id, $data) {
    return $this->redis->hMSet($this->prefix.$session_id, array('expires' => time(), 'data' => $data));
  }
  
  // 在自動(dòng)開(kāi)始會(huì)話或者通過(guò)調(diào)用 session_start() 函數(shù)手動(dòng)開(kāi)始會(huì)話之后，PHP 內(nèi)部調(diào)用 read 回調(diào)函數(shù)來(lái)獲取會(huì)話數(shù)據(jù)。
  public function read($session_id) {
    if($this->redis->exists($this->prefix.$session_id)) {
      return $this->redis->hGet($this->prefix.$session_id, 'data');
    }
    return '';
  }
  
  // 清除會(huì)話中的數(shù)據(jù)，當(dāng)調(diào)用session_destroy()函數(shù)，或者調(diào)用 session_regenerate_id()函數(shù)并且設(shè)置 destroy 參數(shù)為 TRUE 時(shí),會(huì)調(diào)用此回調(diào)函數(shù)。
  public function destroy($session_id) {
    if($this->redis->exists($this->prefix.$session_id)) {
      return $this->redis->del($this->prefix.$session_id) > 0 ? true : false;
    }
    return true;
  }
  
  // 垃圾回收函數(shù)，調(diào)用周期由 session.gc_probability 和 session.gc_divisor 參數(shù)控制
  public function gc($maxlifetime) {
    $allKeys = $this->redis->keys("{$this->prefix}*");
    foreach($allKeys as $key) {
      if($this->redis->exists($key) && $this->redis->hGet($key, 'expires') + $maxlifetime < time()) {
        $this->redis->del($key);
      }
    }
    return true;
  }
}

// 調(diào)用自定義的session處理方法
$handler = new Session_custom();
session_set_save_handler(
  array($handler, 'open'),
  array($handler, 'close'),
  array($handler, 'read'),
  array($handler, 'write'),
  array($handler, 'destroy'),
  array($handler, 'gc')
);

// 下面這行代碼可以防止使用對(duì)象作為會(huì)話保存管理器時(shí)可能引發(fā)的非預(yù)期行為,表示當(dāng)腳本執(zhí)行之后或調(diào)用exit()之后，存儲(chǔ)當(dāng)前會(huì)話數(shù)據(jù)并關(guān)閉當(dāng)前會(huì)話
register_shutdown_function('session_write_close');

session_start();

// 可以使用session了