php中將session保存到數據庫的代碼

我們可以使用session_set_save_handler()來注冊連接數據的函數。下面是完整的演示代碼

<?php
//
// 'sessions' table schema
// create table sessions (
//   session_id char(32) not null,
//   session_data text not null,
//   session_expiration int(11) unsigned not null,
//   primary key (session_id));
//

include_once 'DB.php';
// Global Variables
$dbh = NULL;
function on_session_start ($save_path, $session_name) {
    global $dbh;
    $dbh = DB::connect('mysql://user:secret@localhost/SITE_SESSIONS',
                       true);

if (DB::isError($dbh)) {
    die(sprintf('Error [%d]: %s',
                $dbh->getCode(), $dbh->getMessage()));
}

}
function on_session_end ()
{
   // Nothing needs to be done in this function
   // since we used persistent connection.
}
function on_session_read ($key)
{
    global $dbh;

$stmt = "select session_data from sessions";
$stmt .= " where session_id = '$key'";
$stmt .= " and session_expiration > now()";

$sth = $dbh->query($sth);
$row = $sth->fetchRow(DB_FETCHMODE_ASSOC);
return $row['session_data'];

}
function on_session_write ($key, $val)
{
    global $dbh;

$val = addslashes($val);

$insert_stmt = "insert into sessions values('$key', '$val', now() + 3600)";
$update_stmt = "update sessions set session_data = '$val', ";
$update_stmt .= "session_expiration = now() + 3600 ";
$update_stmt .= "where session_id = '$key'";

// First we try to insert, if that doesn't succeed, it means
// session is already in the table and we try to update
if (DB::isError($dbh->query($insert_stmt)))
    $dbh->query($update_stmt);

}
function on_session_destroy ($key)
{
    global $dbh;
$stmt = "delete from sessions where session_id = '$key'";
   $dbh->query($stmt);
}
function on_session_gc ($max_lifetime)
{
    global $dbh;

// In this example, we don't use $max_lifetime parameter
// We simply delete all sessions that have expired
$stmt = "delete from sessions where session_expiration < now()";
$dbh->query($stmt);

}
session_start ();
// Register the $counter variable as part
// of the session
session_register ("counter");
// Set the save handlers
session_set_save_handler ("on_session_start",   "on_session_end",
                          "on_session_read",    "on_session_write",
                          "on_session_destroy", "on_session_gc");
// Let's see what it does
$counter++;
print $counter;
session_destroy();
?></pre>