原文 http://codeigniter.org.cn/forums/viewthread.php?tid=1757&extra=&highlight=session&page=1
CI的session有点问题，很多时候需要挂载其他的扩展session，坛子里网友推荐了kndb session，我大致用了一下，下面简单介绍下用法：
第一步：建立系统数据库，这里假设数据库名是test；
第二步：建立存储session的数据表sessions
SQL
CREATE TABLE sessions (
session_id varchar(32) NOT NULL,
session_last_access int(10) UNSIGNED,
session_data text,
PRIMARY KEY (session_id)
);
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第三步：修改CI文件夹/system/application/config/config.php
PHP
$config[‘sess_cookie_name’] = ‘CISESSION’;
$config[‘sess_expiration’] = 7200;
$config[‘sess_encrypt_cookie’] = FALSE;
$config[‘sess_table_name’] = ‘sessions’;
$config[‘sess_match_ip’] = TRUE;
$config[‘sess_match_useragent’] = TRUE;
$config[‘sess_use_database’] = TRUE;
$config[‘sess_time_to_update’] = 300;
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第四步：在CI文件夹/system/application/libraries下建立文件Session.php，输入以下内容
PHP
object =& get_instance();
// set config variables
$this->_lifetime = $this->object->config->item(‘sess_expiration’);
$this->_sess_id_ttl = $this->object->config->item(‘sess_time_to_update’);
$this->_match_ip = $this->object->config->item(‘sess_match_ip’);
$this->_match_useragent = $this->object->config->item(‘sess_match_useragent’);
$this->_useDB = $this->object->config->item(‘sess_use_database’);
$this->_sess_table = $this->object->config->item(‘sess_table_name’);
log_message(‘debug’, “Session Class Initialized”);
$this->_sess_run();
}
/**
* Starts up the session system for current request
*/
function _sess_run()
{
// Set session table and register this object as the session handler, if using databases
if ($this->_useDB == TRUE) {
session_set_save_handler(array(&$this, “_open”), array(&$this, “_close”), array(&$this, “_read”),
array(&$this, “_write”),array(&$this, “_destroy”),array(&$this, “_gc”));
}
session_start();
// if no lifetime set in config, set to 2 years
if (!is_numeric($this->_lifetime) || $this->_lifetime <= 0) {
$this->_lifetime = (60*60*24*365*2);
}
// if no session ID regeneration time set in config, set to 30 minutes
if (!is_numeric($this->_sess_id_ttl) || $this->_sess_id_ttl <= 0) {
$this->_sess_id_ttl = 1800;
}
// check if session has expired
if ($this->_session_expired()) {
$this->sess_destroy();
return FALSE;
}
// match IP address if necessary
if ($this->_match_ip == TRUE) {
if ($this->_ips_match() == FALSE) {
$this->sess_destroy();
return FALSE;
}
}
// match user agent if necessary
if ($this->_match_useragent == TRUE) {
if ($this->_useragents_match() == FALSE) {
$this->sess_destroy();
return FALSE;
}
}
// regenerate session id if necessary
// session data stays the same, but old session storage is destroyed
if ( $this->_sess_id_expired() ) {
$this->regenerate_id();
}
// delete old flashdata (from last request)
$this->_flashdata_sweep();
// mark all new flashdata as old (data will be deleted before next request)
$this->_flashdata_mark();
// finally, set last access time to now
$this->set_userdata(‘sess_last_access’, time());
}
/**
* Checks if session has expired
*/
function _session_expired()
{
// if this is the first time coming in, initialize access time
if (!$this->userdata(‘sess_last_access’)) {
$this->set_userdata(‘sess_last_access’, time());
return FALSE;
}
$delta = time() – $this->userdata(‘sess_last_access’);
if ($delta >= $this->_lifetime ) {
return true;
}
return false;
}
/**
* Checks if stored IP matches current IP
*/
function _ips_match() {
// if this is the first time coming in, initialize IP address
if (!$this->userdata(‘sess_ip_address’)) {
$this->set_userdata(‘sess_ip_address’, $this->object->input->ip_address());
return TRUE;
}
return $this->userdata(‘sess_ip_address’) == $this->object->input->ip_address();
}
/**
* Checks if stored user agent matches current user agent
*/
function _useragents_match() {
// if this is the first time coming in, initialize user agent
if (!$this->userdata(‘sess_useragent’)) {
$this->set_userdata(‘sess_useragent’, trim(substr($this->object->input->user_agent(), 0, 50)));
return TRUE;
}
return $this->userdata(‘sess_useragent’) == trim(substr($this->object->input->user_agent(), 0, 50));
}
/**
* Checks if session id needs regenerating
*/
function _sess_id_expired()
{
// if this is the first time coming in, initialize regenerated time
if (!$this->userdata(‘sess_last_regenerated’)) {
$this->set_userdata(‘sess_last_regenerated’, time());
return false;
}
$delta = time() – $this->userdata(‘sess_last_regenerated’);
if ( $delta >= $this->_sess_id_ttl ) {
return true;
}
return false;
}
/**
* Regenerates session id
*/
function regenerate_id()
{
// regenerate session id and store it
// $delete_old_session parameter works in PHP5 only!
session_regenerate_id(TRUE);
// update the session generation time
$this->set_userdata(‘sess_last_regenerated’, time());
}
/**
* Destroys the session and erases session storage
*/
function sess_destroy()
{
session_unset();
if ( isset( $_COOKIE[session_name()] ) )
{
//@@@ was having trouble just using setcookie() because it wasn’t unsetting fast enough
unset($_COOKIE[session_name()]);
setcookie(session_name(), ”, time()-42000, ‘/’); //@@@
}
session_destroy();
}
/**
* returns the session id of the currentsession
*/
function get_sess_id() {
return session_id();
}
/**
* Reads given session attribute value: single variable, element of single dimensional array, or property of object
* I was kind of of two minds about whether the object bit should be implemented
* so you can take out that logic if you wish
*/
function userdata($item, $subitem=null)
{
// this item is in an array
if ($subitem) {
if ($subitem == ‘session_id’){ //added forbackward-compatibility
return session_id();
} else {
// array vs. object: handled differently
if (isset($_SESSION[$item])) {
if (is_array($_SESSION[$item])) return (!isset($_SESSION[$item][$subitem])) ? false : $_SESSION[$item][$subitem];
if (is_object($_SESSION[$item])) return(!isset($_SESSION[$item]->$subitem)) ? false :$_SESSION[$item]->$subitem;
return false;
}
}
}
// this item is not in an array
else {
if($item == ‘session_id’){ //added for backward-compatibility
return session_id();
} else {
return ( ! isset($_SESSION[$item])) ? false : $_SESSION[$item];
}
}
}
/**
* Returns all session data
*/
function all_userdata()
{
if (isset($_SESSION[‘session_id’])) { //added for backward-compatibility
$_SESSION[‘session_id’] = session_id();
}
return $_SESSION;
}
/**
* Sets session attributes to the given values
*/
function set_userdata($newdata = array(), $newval = ”)
{
if (is_string($newdata))
{
$newdata = array($newdata => $newval);
}
if (count($newdata) > 0)
{
foreach ($newdata as $key => $val)
{
$_SESSION[$key] = $val;
}
}
}
/**
* Erases given session attributes
*/
function unset_userdata($newdata = array())
{
if (is_string($newdata))
{
$newdata = array($newdata => ”);
}
if (count($newdata) > 0)
{
foreach ($newdata as $key => $val)
{
unset($_SESSION[$key]);
}
}
}
/**
* Sets “flash” data which will be available only in next request (then it will
* be deleted from session). You can use it to implement “Save succeeded” messages
* after redirect.
*/
function set_flashdata($key, $value)
{
$flash_key = $this->_flash_key.’:new:’.$key;
$this->set_userdata($flash_key, $value);
}
/**
* Keeps existing “flash” data available to next request.
*/
function keep_flashdata($key)
{
$old_flash_key = $this->_flash_key.’:old:’.$key;
$value = $this->userdata($old_flash_key);
$new_flash_key = $this->_flash_key.’:new:’.$key;
$this->set_userdata($new_flash_key, $value);
}
/**
* Returns “flash” data for the given key.
*/
function flashdata($key)
{
$flash_key = $this->_flash_key.’:old:’.$key;
return $this->userdata($flash_key);
}
/**
* PRIVATE: Internal method – marks “flash” session attributes as ‘old’
*/
function _flashdata_mark()
{
foreach ($_SESSION as $name => $value)
{
$parts = explode(‘:new:’, $name);
if (is_array($parts) && count($parts) == 2)
{
$new_name = $this->_flash_key.’:old:’.$parts[1];
$this->set_userdata($new_name, $value);
$this->unset_userdata($name);
}
}
}
/**
* PRIVATE: Internal method – removes “flash” session marked as ‘old’
*/
function _flashdata_sweep()
{
foreach ($_SESSION as $name => $value)
{
$parts = explode(‘:old:’, $name);
if (is_array($parts) && count($parts) == 2 && $parts[0] == $this->_flash_key)
{
$this->unset_userdata($name);
}
}
}
/************* DATABASE METHODS ***************/
function _open()
{
if ($this->_sess_db = mysql_connect($this->object->db->hostname,
$this->object->db->username,
$this->object->db->password)) {
return mysql_select_db($this->object->db->database, $this->_sess_db);
}
return FALSE;
}
function _close()
{
if ($this->_sess_db) {
return mysql_close($this->_sess_db);
}
return TRUE;
}
function _read($id)
{
$id = mysql_real_escape_string($id);
$sql = “SELECT session_data FROM $this->_sess_table WHERE session_id = ‘$id'”;
if ($result = mysql_query($sql, $this->_sess_db)) {
if (mysql_num_rows($result)) {
$record = mysql_fetch_assoc($result);
return $record[‘session_data’];
}
}
return ”;
}
function _write($id, $data)
{
$access = time();
$id = mysql_real_escape_string($id);
$access = mysql_real_escape_string($access);
$data = mysql_real_escape_string($data);
$sql = “REPLACE INTO $this->_sess_table VALUES (‘$id’, ‘$access’, ‘$data’)”;
return mysql_query($sql, $this->_sess_db);
}
function _destroy($id)
{
$id = mysql_real_escape_string($id);
$sql = “DELETE FROM $this->_sess_table WHERE session_id = ‘$id'”;
return mysql_query($sql, $this->_sess_db) or die(“failed to delete
“);
}
function _gc($max)
{
$old = time() – $max;
$old = mysql_real_escape_string($old);
$sql = “DELETE FROM $this->_sess_table WHERE session_last_access < '$old'";
return mysql_query($sql, $this->_sess_db);
}
}
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第五步：修改CI文件夹/system/application/config/autoload.php
加入自动装载类库database和session，类似以下配置
PHP
$autoload[‘libraries’] = array(‘database’,’session’);
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这里主要介绍使用数据库存储session的方法，如果需要用文件型的session，只要简单的在CI的配置文件里设置：
PHP
$config[‘sess_use_database’] = False;
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kndb session的wiki地址是：http://codeigniter.com/wiki/KNDB_Session/