session入库可以解决哪些问题？
1. 可以解决跨域操作
2. 可以实现单点登陆
3. 可以统计在线人数
4. 可以实现同一时只允许一个用户在线
session_set_save_handler的回掉函数描述
实现session入库
第一步：在php.ini配置文件中设置session.save_headler=user(默认是file)
或者使用ini_set设置ini_set(‘session.save_handler’,’user’);
第二步：创建一个存放session的数据表
session_id用于存放session_id的，字段类型为字符型,长度为32
session_value用于存放session的内容,字段类型为text
session_life 用于存放session的生存期
第三步：session_set_save_handler ( callback $open , callback $close ,callback $read , callback $write , callback $destroy , callback $gc )
第四步：代码实现
<?php
header('content-type:text/html;charset=utf-8');
//将session存储方式设置为存入数据库的方式
//session.save_handler = files
ini_set("session.save_handler", "user");
session_set_save_handler("open", "close", "read", "write", "destroy", "gc");
//打开并连接数据库
function open()
{
//使用pdo
$pdo = new PDO('mysql:host=127.0.0.1;dbname=yii','root','root');
$pdo->exec('set names utf8');
}
//关闭连接
function close()
{
//使用pdo
$pdo = new PDO('mysql:host=127.0.0.1;dbname=yii','root','root');
$pdo->exec('set names utf8');
$pdo = null;
}
//从表中中读信息
function read($session_id)
{
//使用pdo
$pdo = new PDO('mysql:host=127.0.0.1;dbname=yii','root','root');
$pdo->exec('set names utf8');
$read = $pdo->query("select * from session where session_id='$session_id'")->fetch(PDO::FETCH_ASSOC);
return $read["session_info"];
}
//将session存入数据库
function write ($session_id,$session_info)
{
// echo $session_id. " " . $session_info;
//使用pdo
$pdo = new PDO('mysql:host=127.0.0.1;dbname=yii','root','root');
$pdo->exec('set names utf8');
$read = $pdo->query("select * from session where session_id='$session_id'")->fetch(PDO::FETCH_ASSOC);
if(empty($read))
{
$time = time();
$pdo->exec("insert into session (session_id, session_info, session_life) values ('$session_id', '$session_info', '$time')");
}
else
{
$sql = "update session set session_info='$session_info' where session_id='$session_id'";
$pdo->exec($sql);
}
}
//销毁指定session
function destroy($session_id)
{
//使用pdo
$pdo = new PDO('mysql:host=127.0.0.1;dbname=yii','root','root');
$pdo->exec('set names utf8');
$pdo->exec("delete from session where session_id='$session_id'");
}
//删除所有过期的session
function gc()
{
}
session_start();
//判断是否有session
if(isset($_SESSION['name']))
{
$status = 1;
}
else
{
$status = 0;
}
//获取需要接收的值
$user_name = isset($_POST['user_name'])?$_POST['user_name']:null;
$user_pwd = isset($_POST['user_pwd'])?$_POST['user_pwd']:null;
//使用pdo
$pdo = new PDO('mysql:host=127.0.0.1;dbname=yii','root','root');
$pdo->exec('set names utf8');
$sql = "select * from user where username = '$user_name' and password = '$user_pwd' ";
$re = $pdo->query($sql)->fetch(PDO::FETCH_ASSOC);
if($re)
{
$status = 1;
$_SESSION['name'] = $user_name;
}
?>
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Document</title>
</head>
<body>
<?php if($status == 0){?>
<h3>服务器3</h3>
<form action="a.php" method="post">
<table>
<tr>
<td>姓名：</td>
<td><input type="text" name="user_name"></td>
</tr>
<tr>
<td>密码：</td>
<td><input type="password" name="user_pwd"></td>
</tr>
<tr>
<td></td>
<td><input type="submit" value="登录"></td>
</tr>
</table>
</form>
<?php } else{?>
<h2>欢迎<?=$_SESSION['name']?>登录</h2>
<h3>服务器3</h3>
<?php }
?>
</body>
</html>
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作者：bchz521
来源：CSDN
原文：https://blog.csdn.net/bu2543567472/article/details/70937144
版权声明：本文为博主原创文章，转载请附上博文链接！
