将PHP的session数据存储到数据库中的代码实例


            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;

    }

  }

 

}











$dbLink = new mysqli("localhost", "root", "root", "test");

$sessionTable = "sessioninfo";

 

$handler = new MySessionHandler($dbLink, $sessionTable);

session_set_save_handler($handler);

session_start();

$_SESSION['name'] = "test";

echo $_SESSION["name"];

//session_destroy();