php session session_set_save_handler 机制

发表于 2017-01-05 08:22:22 by 月小升

php自身带功能，将session的数据从之前的files 改变到其他任何地方。比如mysql redis等等，方便你分布式的集群应用。
看一下原理

Can't connect to $SESS_DBHOST as $SESS_DBUSER";   
        echo "
MySQL Error: " . mysql_error();   
        die;   
    }   
  
    if (! mysql_select_db($SESS_DBNAME, $SESS_DBH)) {   
        echo "
Unable to select database $SESS_DBNAME";   
        die;   
    }   
  
    return true;   
}   
  
function sess_close() {   
    return true;   
}   
  
function sess_read($key) {   
    global $SESS_DBH, $SESS_LIFE;   
  
    $qry = "SELECT value FROM session_tbl WHERE sesskey = '$key' AND expiry > " . time();   
    $qid = mysql_query($qry, $SESS_DBH);   
  
    if (list($value) = mysql_fetch_row($qid)) {   
        return $value;   
    }   
  
    return false;   
}   
  
function sess_write($key, $val) {   
    global $SESS_DBH, $SESS_LIFE;   
  
    $expiry = time() + $SESS_LIFE; //过期时间   
    $value = addslashes($val);   
  
    $qry = "INSERT INTO session_tbl VALUES ('$key', $expiry, '$value')";   
    $qid = mysql_query($qry, $SESS_DBH);   
  
    if (! $qid) {   
        $qry = "UPDATE session_tbl SET expiry = $expiry, value = '$value' WHERE sesskey = '$key' AND expiry > " . time();   
        $qid = mysql_query($qry, $SESS_DBH);   
    }   
  
    return $qid;   
}   
  
function sess_destroy($key) {   
    global $SESS_DBH;   
  
    $qry = "DELETE FROM session_tbl WHERE sesskey = '$key'";   
    $qid = mysql_query($qry, $SESS_DBH);   
  
    return $qid;   
}   
  
function sess_gc($maxlifetime) {   
    global $SESS_DBH;   
  
    $qry = "DELETE FROM session_tbl WHERE expiry < " . time();   
    $qid = mysql_query($qry, $SESS_DBH);   
  
    return mysql_affected_rows($SESS_DBH);   
}   
  
session_set_save_handler(   
"sess_open",   
"sess_close",   
"sess_read",   
"sess_write",   
"sess_destroy",   
"sess_gc");   
  
session_start();   

?>  

使用方法：
在使用session前
将之前的session_start（）
改成

 require_once("session.class.php");

CREATE TABLE IF NOT EXISTS `session_tbl` (
  `sesskey` varchar(255) NOT NULL,
  `expiry` varchar(255) NOT NULL,
  `value` varchar(255) NOT NULL,
  UNIQUE KEY `sesskey_2` (`sesskey`),
  KEY `sesskey` (`sesskey`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8;

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首发地址：月小升博客 – https://java-er.com/blog/php-session-session_set_save_handler/
无特殊说明，文章均为月小升原创，欢迎转载，转载请注明本文地址，谢谢