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php同个用户同时只能登陆一个, 后登陆者踢掉前登陆者(2010-04-21 17:45)

分类：PHP

php同个用户同时只能登陆一个, 后登陆者踢掉前登陆者

通常用户登陆,如果没有特别的限定, 同一个用户可以同时登陆, 今天搞了一个东西限定一个用户不能同时登陆到一个系统上, 后登陆者会把前面登陆的踢出来.(有点像QQ,同个帐号不能在多个地方同时在线, 后面登陆成功后就把前面登陆的掉线)

SQL : 两张表,一张是用户信息,另一张用来保存session

-- 数据库: `single_user`

CREATE TABLE IF NOT EXISTS `session` (

`username` varchar(50) default '',

`time` varchar(14) default '',

`session_id` varchar(200) NOT NULL default '0',

`userid` int(11) default '0',

PRIMARY KEY (`session_id`)

) ENGINE=MyISAM DEFAULT CHARSET=utf8;

CREATE TABLE IF NOT EXISTS `users` (

`userid` int(11) NOT NULL auto_increment,

`username` varchar(255) NOT NULL,

`password` varchar(255) NOT NULL,

PRIMARY KEY (`userid`)

) ENGINE=MyISAM DEFAULT CHARSET=utf8 AUTO_INCREMENT=2 ;

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数据表 session 以session_id 为主键, 这个主键是 userid + user name + user login time 的 md5值算出来的. 每次用户登陆的时候就会像session表里插入一条,同时以userid username为条件查询旧的session记录并且删除他,所以当页面判断当前用户是否有效时,是通过$_SESSION数组里面保存在session_id值和数据库里取出来的session_id进行比较, 旧的session_id 在此用户第2次登陆时已经被删除,因此找不到,从而被退出系统.

代码部分

1.config.php 一些简单的配置,包括数据库的连接

<?php

$live_site = 'testing';

$session_life = 600;

function getConnect()

{

$db_local = 'localhost';

$db_user = 'root';

$db_pwd = '';

$db_name = 'single_user';

$db_link = mysql_connect($db_local, $db_user, $db_pwd);

$rs = mysql_select_db($db_name, $db_link);

if ($rs)

{

return $db_link;

}

return false;

}

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2. index.php 登陆页面

<?php

require_once('config.php');

$db = getConnect();

if (isset($_POST['username']) && isset($_POST['password']))

{

//处理用户登陆后的数据验证

$query = 'SELECT * FROM `users` WHERE `username`="' . trim($_POST['username']) . '" AND `password`="' .md5( trim( $_POST['password'] ) ) . '"';

$result = mysql_query($query, $db);

$rs_num = mysql_num_rows($result);

if ($rs_num > 0 )

{

//该用户存在

$row = mysql_fetch_assoc($result);

$userid = $row['userid'];

$username = $row['username'];

$logintime = time();

//创建session_id值

$session_id = md5( $userid . $username . $logintime );

//登陆成功后要插入一条记录到session表中

$sql = 'INSERT INTO session SET `time`="'.$logintime.'", `session_id`="'.$session_id.'", `userid`='.$userid.', `username`="'.$username.'"';

mysql_query($sql, $db);

//并且要把session表里旧的session_id删除掉

$query = 'DELETE FROM `session` WHERE `userid`=' . $userid . ' AND `username`="' . $username . '" AND `session_id`!="' . $session_id . '"';

$old_session = mysql_query($query);

//开启session, 把新登陆的用户信息进入$_SESSION中

session_name( md5( $live_site ) );

session_id( $session_id );

session_start();

$_SESSION['session_id'] = $session_id;

$_SESSION['userid'] = $row['userid'];

$_SESSION['username'] = $row['username'];

$_SESSION['logintime'] = $logintime;

session_write_close();

echo '<script type="text/javascript">window.location.href="index2.php"</script>';

} else {

echo '<script type="text/javascript">window.location.href="index.php?mosmsg=Username Error"</script>';

}

} else {

//用户登陆框

<form method="post" name="user_login" id="user_login" action="index.php">

Username:<input type="text" name="username" id="username" value=""/>

<br />

password:<input type="password" name="password" id="password" value=""/>

<br />

<input type="submit" name="submit" id="submit" value="Submit"/>

</form>

<?php

}

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3. index2.php 用户成功登陆后需要处理原来上一次该用户的session信息, 如果上一次此用户的登陆信息还有效,需要将其删除

<?php

require_once('config.php');

$db = getConnect();

session_name( md5( $live_site ) );

session_start();

$userid = $_SESSION['userid'];

$username = $_SESSION['username'];

$logintime = $_SESSION['logintime'];

$session_id = $_SESSION['session_id'];

//判断用户是否有登陆

if ($session_id != session_id()) {

echo "<script>document.location.href='index.php?mosmsg=Invalid Session'</script>\n";

exit();

}

if ($session_id == md5( $userid . $username . $logintime )) {

$past = time() - $session_life;

//删除已经超时但是记录还存在的记录

$query = "DELETE FROM session"

. "\n WHERE time < '" . (int) $past . "'"

. "\n AND userid <> 0"

;

mysql_query($query);

$current_time = time();

// update session timestamp 更新登陆用户的时间戳

$query = 'UPDATE #__session'

. '\n SET time="' . $current_time . '"'

. '\n WHERE session_id = "' . $session_id . '"';

//以当前用户登陆后产生的$session_id 来查询 session表里的记录是否存在

//如果不存在那么就跳到登陆页面

$query = "SELECT COUNT( session_id )"

. "\n FROM session"

. "\n WHERE session_id = '" . $session_id . "'"

. "\n AND username = '". $username . "'"

. "\n AND userid = ". $userid;

$session_rs = mysql_query($query);

$session_row = mysql_fetch_row($session_rs);

$session_num = $session_row[0];

if ($session_num > 0 )

{

echo 'WELCOME<br / ><a href="logout.php">Logout</a>';

} else {

echo "<script>document.location.href='index.php?mosmsg=Admin Session Expired'</script>\n";

}

} else {

// session id does not correspond to required session format

echo "<script>document.location.href='index.php?mosmsg=Invalid Session'</script>\n";

exit();

}

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4. logout.php 退出用户,并且删除 SESSION

<?php

require_once('config.php');

$db = getConnect();

session_name( md5( $live_site ) );

session_start();

$userid = $_SESSION['userid'];

$username = $_SESSION['username'];

$logintime = $_SESSION['logintime'];

$session_id = $_SESSION['session_id'];

$sql = 'DELETE FROM session WHERE userid='.$userid.' AND username="'.$username.'" AND session_id = "'.$session_id.'"';

mysql_query($sql);

session_destroy();

echo "<script>document.location.href='index.php'</script>\n";

exit();

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作者：grev | 浏览：(4691) | 评论：(0)

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