php session自定义处理

原文：http://www.cnblogs.com/mrcoke/  这个人的博客上转的。

这个博客也好： 学算法和数据结构！！http://blog.csdn.net/21aspnet/article/category/286009

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PHP session自定义处理，将session保存到数据库中！！！

session.gc_probability = 1        //默认是1 ，越大越好

session.gc_divisor     = 100     //默认是100，越小越好

// 默认是一百次请求调用一次gc 。session.gc_probability相当于分子，session.gc_divisor相当于分母。如果想每次都调用gc 两个改成一样就可以了

session.gc_maxlifetime = 30   // session生存时间

<?php
 function session_open($session_path, $session_name)
 {
  mysql_connect('localhost', 'root', 'root');
  mysql_select_db('demo');
  mysql_query("SET NAMES utf8");
 }
 
 function session_close()
 {
  return TRUE;
 }
 
 function session_read($SID)
 {
  $query = "SELECT value FROM session where SID= '$SID' AND expiration >".time();
  $result = mysql_query($query);
  if(mysql_num_rows($result))
  {
   $row = mysql_fetch_assoc($result);
   $value = $row['value'];
   return $value;
  }else
  {
   return FALSE;
  }
 }
 
 function session_write($SID, $value)
 {
  $lifetime = get_cfg_var("session.gc_maxlifetime");
  $expiration = time() + $lifetime;
  $query = "INSERT INTO session VALUES('$SID', '$expiration', '$value')";
  $result = mysql_query($query);
  
  if (!$result)
  {
   $query = "UPDATE session SET expiration = '$expiration', value = '$value' WHERE SID = '$SID' AND expiration >".time();
   $result = mysql_query($query);
  } 
 }
 
 function sessionDestroy($SID)
 {
  $query = "DELETE FROM session WHERE SID = '$SID'";
  $result = mysql_query($query);
 }
 
 function session_gc()
 {
  $query = "DELETE FROM session WHERE expiration <".time();
  $result = mysql_query($query);
  echo mysql_affected_rows();
 }
 
 session_set_save_handler("session_open", "session_close", "session_read", "session_write", "sessionDestroy", "session_gc");
 session_start();
 
?>