一个开发环境有多个网站，需要使用不同的session，解决方案很多。不过这次也高大上一把，用数据库存，方便以后扩展。
PostgreSQL版
首先是数据库的部分
--drop table php_session create unlogged table php_session ( sess_id varchar(32) primary key, modify_time timestamp with time zone not null, sess_data varchar(3000) default '' ); create index concurrently idx_php_session_modify_time on php_session(modify_time); --set_session(id, data) create or replace function set_session(varchar, varchar) returns void as $set_session$ with upsert as ( update php_session set modify_time = current_timestamp, sess_data = $2 where sess_id = $1 returning 1 ) insert into php_session (sess_id, modify_time, sess_data) select $1, current_timestamp, $2 where not exists ( select 1 from upsert ); $set_session$ language sql; --get_session(id) create or replace function get_session(varchar) returns varchar as $get_session$ select sess_data from php_session where sess_id = $1 $get_session$ language sql; --del_session create or replace function del_session(varchar) returns void as $del_session$ delete from php_session where sess_id = $1 $del_session$ language sql; --gc_session create or replace function gc_session() returns void as $del_session$ delete from php_session where modify_time < current_timestamp - interval '30 days' $del_session$ language sql;
然后是PHP的部分
<?php session_set_save_handler( function ($savePath, $sessionName) {//open return true; }, function () {//close return true; }, function ($id) {//read $sql = "select get_session($1)"; $stmt = pg_query_params(SESSION_CONN, $sql, array($id)); $result = pg_fetch_row($stmt); return $result[0]; }, function ($id, $data) {//write $sql = "select set_session($1, $2)"; pg_query_params(SESSION_CONN, $sql, array($id, $data)); return true; }, function ($id) {//destroy $sql = "select del_session($1)"; pg_query_params(SESSION_CONN, $sql, array($id, $data)); return true; }, function ($maxlifetime) {//gc //php needn't control the global session gc return true; } ); register_shutdown_function('session_write_close'); ?>
然后只要在session_start之前调用这个就可以了
至于SESSION_CONN，那是我定义的一个常量，表示一个指向session数据库的链接而已。
MySQL版
再总结一个针对MySQL的集成更多基础功能的例子：
表结构：
CREATE TABLE IF NOT EXISTS `sessioninfo` ( `sid` varchar(255) NOT NULL, `value` text NOT NULL, `expiration` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP, PRIMARY KEY (`sid`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8;
session信息存储到数据库的类：
class MySessionHandler implements SessionHandlerInterface { /** * @access private * @var object 数据库连接 */ private $_dbLink; /** * @access private * @var string 保存session的表名 */ Private $_sessionTable; /** * @access private * @var string session名 */ private $_sessionName; /** * @const 过期时间 */ const SESSION_EXPIRE = 10; public function __construct($dbLink, $sessionTable) { if(!is_object($dbLink)) { return false; } $this->_dbLink = $dbLink; $this->_sessionTable = $sessionTable; } /** * 打开 * @access public * @param string $session_save_path 保存session的路径 * @param string $session_name session名 * @return integer */ public function open($session_save_path, $session_name) { $this->_sessionName = $session_name; return 0; } /** * 关闭 * @access public * @return integer */ public function close() { return 0; } /** * 关闭session * @access public * @param string $session_id session ID * @return string */ public function read($session_id) { $query = "SELECT value FROM {$this->_sessionTable} WHERE sid = {$session_id} AND UNIX_TIMESTAMP(expiration) + " . self::SESSION_EXPIRE . " > UNIX_TIMESTAMP(NOW())"; $result = $this->_dbLink->query($query); if(!isset($value) || empty($value)) { $value = ""; return $value; } $this->_dbLink->query("UPDATE {$this->_sessionTable} SET expiration = CURRENT_TIMESTAMP() WHERE sid = {$session_id}"); $value = $result->fetch_array(); $result->free(); return $value['value']; } /** * 写入session * @access public * @param string $session_id session ID * @param string $session_data session data * @return integer */ public function write($session_id, $session_data) { $query = "SELECT value FROM {$this->_sessionTable} WHERE sid = '{$session_id}' AND UNIX_TIMESTAMP(expiration) + " . self::SESSION_EXPIRE . " > UNIX_TIMESTAMP(NOW())"; $result = $this->_dbLink->query($query); $result = $result->fetch_array(); if(!empty($result)) { $result = $this->_dbLink->query("UPDATE {$this->_sessionTable} SET value = {$session_data} WHERE sid = {$session_id}"); } else{ $result = $this->_dbLink->query("INSERT INTO {$this->_sessionTable} (sid, value) VALUES ('{$session_id}', '{$session_data}')"); } if($result){ return 0; } else{ return 1; } } /** * 销魂session * @access public * @param string $session_id session ID * @return integer */ public function destroy($session_id) { $result = $this->_dbLink->query("DELETE FROM {$this->_sessionTable} WHERE sid = '{$session_id}'"); if($result){ return 0; } else{ return 1; } } /** * 垃圾回收 * @access public * @param string $maxlifetime session 最长生存时间 * @return integer */ public function gc($maxlifetime) { $result = $this->_dbLink->query("DELETE FROM {$this->_sessionTable} WHERE UNIX_TIMESTAMP(expiration) < UNIX_TIMESTAMP(NOW()) - " . self::SESSION_EXPIRE); if($result){ return 0; } else{ return 1; } } }