Detailed explanation of the application of php session

This article mainly introduces relevant information about the application of php session in detail. Friends in need can refer to

php session advanced application

Session is very important in web technology. Since the web page is a stateless connection program, the user's browsing status cannot be known. Through the session, the user's relevant information can be recorded for confirmation when the user submits a request to the web server again in this capacity.

For example: When a user browses an e-commerce website, if there is no session, the user needs to enter the account password every time he browses.

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1, Session temporary files

In the server, if all user sessions are saved in the temporary directory, the security and efficiency of the server will be reduced. Opening a site stored on the server will be very slow.

Using the PHP function session_save_path() function to store session temporary files can alleviate the problems of reduced server efficiency and slow site opening caused by the storage of temporary files.

The sample code is as follows:

<?php
$path ="./tmp/";    //设置session存储的路径
session_save_path($path);
session_start();
$_SESSION[&#39;userName&#39;]=true;
?>

Note

session_save_path() must be executed before session_start().

2, Session cache

Session cache temporarily stores the content in the web page to the Temporary INternet Files folder of the IE client, and the cache time can be set.

Session cache uses the session_cache_limiter() function, whose syntax is as follows:

string session_cache_limiter([string cache_limiter]);

The parameter cache_limiter is public or private. Colleagues session is not on the server side, but on the client side. Not shown on the server.

To set the cache time, use the function session_cache_expire(). The syntax is as follows:

int session_cache_expire([int new_cahche_expire]);

The parameter new_cahche_expire is the time number of the session cache, in minutes.

Note:

These two session functions must be executed before the session_start() function

Example of session cache page The code is as follows:

<?php

session_cache_limiter("private");
$cache_limit =session_cache_limiter();   //开启客户端缓存
echo "缓存限制为：".$cache_limit."\n";
session_cache_expire(30);
$cache_expire = session_cache_expire();  //设定客户端缓存时间
echo "客户端缓存时间为：".$cache_expire."分钟\n";
session_start();

?>

The running results are as follows:

##3, Session database storage

Session database storage in php is mainly implemented through the session_set_save_handler() function. The specific syntax is as follows:

bool session_set_save_handler(string open,string close,string read,string write,string destroy,string gc);

The six parameters (functions) are divided into packages below. After learning object-oriented programming, everyone will have a clearer understanding.

(1) Encapsulate the session_open() function, the code is as follows:

function _session_open($save_path,$session_name){
global $handle;
$handle =mysql_connect('localhost','root','root')or die('数据库连接失败！');
mysql_select_db('db_database11',$handle)or die('数据库不存在');
return(true);
}

(2) Encapsulate the session_close() function, the code is as follows:

function _session_close(){
global $handle;
mysql_close($handle);
return(true);
}

(3) Encapsulate the session_read() function, set the UNIX timestamp of the current time in the function, and search the Session business card and content based on $key. The code is as follows:

function _session_read($key){
golbal $handle;     //全局变量$handle 连接数据库
$time =time();     //设定当前时间
$sql ="select session_data from tb_session where session_key = '$key' and session_time>'$time'";
$result =mysql_query($ssql,$handle);
$row =mysql_fetch_array($result);
if($row){
return($row['session_data']);
}else{
return(false);
}
}

(4) Encapsulate the session_write() function. The function sets the expiration time of the Session and finds the name and content of the Session. If the query result is empty. Then insert the Session in the page into the database based on session_id, session_name, and expiration time. If the query result is not empty, modify the Session storage information in the database based on $key. The code is as follows:

function _session_write($key,$data){
global $handle;
$time = 60*60;
$lapse_time =time()+$time;   //得到UNIX时间戳
$sql = "select session_data from tb_session where session_key ='$key' and session_time>$lapse_time";
$result =mysql_query($sql,$handle);
if(mysql_num_rows($result)==0){  //没有结果
$sql ="insert into tb_session values('$key','$data',$lapse_time)";
$result =mysql_query($sql,$handle);
}else{
$sql ="update tb_session set session_key='$key',session_data ='$data',session_time =$lapse_time where session_key ='$key'";
$result =mysql_query($sql,$handle);
}
return($result);
}

(5) Encapsulate session_destroy(), and delete Sessin in the database based on $key. The code is as follows:

function _session_destroy(){
global $handle;
$sql ="delete from tb_session where session_key ='$key'";
$result =mysql_query($sql,$handle);
}

(6) Encapsulate session_gc(), based on the Session expiration time Delete the expired Session. The sample code is as follows:

functin _session_gc($expiry_time){
global $handle;
$sql ="delete from tb_session where session_expiry_time<$expiry_time";
$result =mysql_query($sql,$handle);
return($result);
}

I will not run the specific code. I will demonstrate it to you when I finish learning object-oriented programming.

The above is the entire content of this article, I hope it will be helpful to everyone's study.

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