session入库

session需要保存的值有三个 会话编号.会话值,过期时间

create table sess(
       sess_id varchar(50) primary key comment '会话编号',
       sess_value varchar(2000) comment '会话内容',
       sess_time int not null comment '会话产生的时间'
)engine=memory charset=utf8 comment '会话表'

创建数据表 :

小建议: 时间可以用datetime 也可以用int 但为什么一般用int?

因为datetime占8字节 int占4字节

保存会话表引擎为什么使用memory?

因为memory引擎将数据存储在内存中 速度极快,重启Mysql服务器数据消失..

代码实现

通过session_set_save_handler 更改会话存储

06.png

<?php
$link=mysqli_connect('localhost','root','root','php15');
mysqli_set_charset($link,'utf8');
function open() {   //开启会话
    return true;
}
function close() {  //关闭会话
    return true;
}
function read($sess_id) {   //读取会话
    global $link;
    $sql="select sess_value from sess where sess_id='$sess_id'";
    $rs=mysqli_query($link,$sql);
    if($rows=mysqli_fetch_row($rs))
        return $rows[0];
    return '';
}
function write($sess_id,$sess_value) {  //写入会话
    global $link;
    $time=time();
    $sql="insert into sess values ('$sess_id','$sess_value',$time) on duplicate key update sess_value='$sess_value',sess_time=$time";
    return mysqli_query($link,$sql);
}
function destroy($sess_id) {    //销毁会话
    global $link;
    $sql="delete from sess where sess_id='$sess_id'";
    return mysqli_query($link,$sql);
}
//$lifetime int PHP的会话生命周期
function gc($lifetime) {    //垃圾回收
    global $link;
    $time=time()-$lifetime; //垃圾时间的临界点
    $sql="delete from sess where sess_time<$time";
    return mysqli_query($link,$sql);
}

session_set_save_handler('open','close','read','write','destroy','gc');
session_start();

$_SESSION['name']='tom';
//session_destroy();

在类中实现继承接口

<?php

$link=mysqli_connect('198.168.38.99','sess','sess','session');
mysqli_set_charset($link,'utf8');

interface SessionHandlerInterface{
    function open();
    function close();
    function read();
    function write();
    function destroy();
    function gc();
}

class MySessionHandler extends SessionHandlerInterface{


  public function open() {   //开启会话
        return true;
    }
   public function close() {  //关闭会话
        return true;
    }
   public function read($sess_id) {   //读取会话
        global $link;
        $sql="select sess_value from sess where sess_id='$sess_id'";
        $rs=mysqli_query($link,$sql);
        if($rows=mysqli_fetch_row($rs))
            return $rows[0];
        return '';
    }
   public function write($sess_id,$sess_value) {  //写入会话
        global $link;
        $time=time();
        $sql="insert into sess values ('$sess_id','$sess_value',$time) on duplicate key update sess_data='$sess_value',sess_time=$time";
        return mysqli_query($link,$sql);
    }
   public function destroy($sess_id) {    //销毁会话
        global $link;
        $sql="delete from sess where sess_id='$sess_id'";
        return mysqli_query($link,$sql);
    }
    //$lifetime int PHP的会话生命周期
    public function gc($lifetime) {    //垃圾回收
        global $link;
        $time=time()-$lifetime; //垃圾时间的临界点
        $sql="delete from sess where sess_time<$time";
        return mysqli_query($link,$sql);
    }
}
session_set_save_handler('open','close','read','write','destroy','gc');
session_start();

$_SESSION['name']='tom';
//session_destroy();