Session 将信息保存在服务器上.服务器在接受到唯一的SESSION_ID后,根据这个ID获取相关数据,然后将信息传递到客户端(浏览器).
Cookie 是将所有信息以文本的形式存在本地文件,并由客户端(浏览器)进行管理与维护.
因为Session 数据存储在server端,所以远程client无法对数据进行修改;而Cookie存储在client本地,容易被获取和篡改.所以Session安全性较高.
SESSION 介绍:
PHP5 后session被设置为全局变量,可以通过 $_SESSION[session_id] 来获取.当页面启动SESSION会话,会在服务器中生成一个带唯一id的SESSION,这个SESSION在生命周期结束前一直有效.当关闭网页或结束生命周期后,session会在服务器中自动注销.
创建一个session 会话需要经过一下4个步骤:
a)启动会话..
方法有2种: bool session_star(); boolean session_register(string name);
b)注册回话.
会话变量被启动后,全部保全在$_SESSION数组当中.通过数组$_SESSION创建一个会话变量很简单,只需要给该数组添加一个变量即可.
c)使用会话:
一般操作:判断对应session_id的SESSION是否存在.不存在创建一个,存在 则通过 $_SESSION[session_id] 使用.
d)删除会话.
unset($_SESSION[session_id]);//删除单个.
unset([$_SESSION]);//删除整个,将禁止整个会话功能,切无法恢复.
$__SESSION=array();//删除整个,可恢复.
session_destroy();//结束当前会话..
SESSION的生命周期:
1.控制session 生命周期的方法:
一. 前提条件:客户端支持COOKIE!
方法:
a>通过Session来完成.
void session_set_cookie_params(int lifetime[,string path][,string domain][,bool secure]);
bool setcookie(string name [,string value] [,int expire] [,string path] [,sting domain] [,secure]);
b>通过Cookie 来完成.
二. 前提条件:客户端不支持COOKIE!
一旦客户端不支持cookie,SESSION就不能在页面间传递,解决办法:
a>.在登陆前提示用户打开cookie.
b>.表单POST/GET方式,来传递SESSION_ID.
c>.设置php.ini文件中的session.use_trans_sid=1 或编译时打开-enable-trans-sid;
d>.通过文件或数据库方式传递SESSION_ID;
服务器上对SESSION性能优化:
在服务器中,如果将所有用户的session都保存到临时目录中,会降低服务器的安全性与效率.
解决方法:将SESSION存储到服务器上的数据库或者临时文件中.
临时文件:
string session_save_path(string path);
数据库:
session 存储在临时文件时,当网站浏览量很大的时候,将会导致查询Session的效率很低,推荐数据库存储形式.
bool session_set_save_handler(string open,string close,string read,string write,string destroy,string gc);//将session_id 存储与数据库中的函数.
SESSION 缓存:
缓存即将页面中的某些信息存储到客户端指定的文件夹中,且可以设置一定的有效时间.(已经经过第一次访问,且存储)在这个有效时间内,当再次访问页面,则可直接从缓存中读取内容,从而提高页面浏览效率.
string session_cache_limiter(string cache_limiter); //缓存函数.
int session_cache_expire([int new cache_expire]); //有效时间.
COOKIE介绍:
cookie 是一种远程客户端存储数据和跟踪识别用户的机制.是服务器临时存放数据在本地用户的一个文本文件.文本文件格式:"用户名@网站地址[数字].txt"
COOKIE 常见功能:
a)记录访客的某些信息. b)在页面间传递变量; c)将页面内容存储到cookie中提高下次访问速度.
慎用COOKIE:
a)不是所有的浏览器都支持cookie.
b)数据是以明文的方式保存在本地,不适合敏感的信息,未加密的信息.
c)不同类型浏览器对cookie 文件有大小,个数限制:比如最多只能存300个cookie 文件,每个大小不超过4KB,每个域名最多支持20个cookie文件.如果超过显示,会随机删除.
创建COOKIE:
bool setcookie(string name [,string value] [,int expire] [,string path] [,sting domain] [,secure]);
读取COOKIE:
$_COOKIE[];
删除COOKIE:
a). setcookie("id", "",time()-1);//值为空,有效时间小于当前时间.0为直接删除COOKIE.
b).手动删除.在客户端找到临时存放cookie的文件.
setcookie()函数后,要执行刷新,cookie才能取得数据:
个人理解是因为session 跟cookie都是在client 跟server之间传输,在页面显示前,我们就必须获取到相应的数据.所以一般是在获取 http:// 或https://时必须带上session 或cookie..当在执行setcookie()时,仅仅在本地存储了cookie 但是地址上并没有带上cookie..因而需要刷新,让服务器给地址协议带上cookie发送个客户端,这样才能取得到值..
正是以上session_star(),setcookie()前,html页面不能有输出...所以说cookie 或者session认第一,就没人敢认第二.

PHP is mainly procedural programming, but also supports object-oriented programming (OOP); Python supports a variety of paradigms, including OOP, functional and procedural programming. PHP is suitable for web development, and Python is suitable for a variety of applications such as data analysis and machine learning.

PHP originated in 1994 and was developed by RasmusLerdorf. It was originally used to track website visitors and gradually evolved into a server-side scripting language and was widely used in web development. Python was developed by Guidovan Rossum in the late 1980s and was first released in 1991. It emphasizes code readability and simplicity, and is suitable for scientific computing, data analysis and other fields.

PHP is suitable for web development and rapid prototyping, and Python is suitable for data science and machine learning. 1.PHP is used for dynamic web development, with simple syntax and suitable for rapid development. 2. Python has concise syntax, is suitable for multiple fields, and has a strong library ecosystem.

PHP remains important in the modernization process because it supports a large number of websites and applications and adapts to development needs through frameworks. 1.PHP7 improves performance and introduces new features. 2. Modern frameworks such as Laravel, Symfony and CodeIgniter simplify development and improve code quality. 3. Performance optimization and best practices further improve application efficiency.

PHPhassignificantlyimpactedwebdevelopmentandextendsbeyondit.1)ItpowersmajorplatformslikeWordPressandexcelsindatabaseinteractions.2)PHP'sadaptabilityallowsittoscaleforlargeapplicationsusingframeworkslikeLaravel.3)Beyondweb,PHPisusedincommand-linescrip

PHP type prompts to improve code quality and readability. 1) Scalar type tips: Since PHP7.0, basic data types are allowed to be specified in function parameters, such as int, float, etc. 2) Return type prompt: Ensure the consistency of the function return value type. 3) Union type prompt: Since PHP8.0, multiple types are allowed to be specified in function parameters or return values. 4) Nullable type prompt: Allows to include null values and handle functions that may return null values.

In PHP, use the clone keyword to create a copy of the object and customize the cloning behavior through the \_\_clone magic method. 1. Use the clone keyword to make a shallow copy, cloning the object's properties but not the object's properties. 2. The \_\_clone method can deeply copy nested objects to avoid shallow copying problems. 3. Pay attention to avoid circular references and performance problems in cloning, and optimize cloning operations to improve efficiency.

PHP is suitable for web development and content management systems, and Python is suitable for data science, machine learning and automation scripts. 1.PHP performs well in building fast and scalable websites and applications and is commonly used in CMS such as WordPress. 2. Python has performed outstandingly in the fields of data science and machine learning, with rich libraries such as NumPy and TensorFlow.


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