PHP cookie与session的有关问题
PHP cookie与session的问题
PHP里,cookie与session相比,除了cookie保存在客户端,不占用服务端的硬盘外,还有啥优点?
PHP处理页面的时候,都是在服务端生成好页面后才发送给客户端,要是把数据缓存在cookie里,就要先把数据发送到客户端,下次访问的时候,再把保存在客户端cookie里的数据发送到服务端,处理后再回发给客户端……这样好像就要比用session缓存数据多了2次传送数据的过程?(session只是在服务器上读取,免去了网络传输?)
不知道这样理解对不对?要是真是这样的话,感觉用cookie缓存数据就没啥优势了……
恳请各位不吝赐教~
谢谢!
(有没有一种稍微简单的,把数据缓存在客户端,服务器处理php文件时不用从客户端再次读取,而是由客户端自动进行处理的技术啊?就是服务器在页面中需要缓存数据的地方留下标记,客户端读取到该标记的时候就去加载缓存的数据……)
------解决方案--------------------
如果把数据都保存在session 当然可以,前提是你是否有足够多的内存支持?
你说的可以使用js+cookie来实现,不过有个问题是cookie所能保存的内容也是有限的.另外也容易伪造
------解决方案--------------------
COOKIE是暴漏的啊,不安全啊,客户端编什么服务器信什么不就蛋疼了。
COOKIE就是一个可退化的会话技术,有没有都不会影响服务端的逻辑与安全。
如果一个用户登录以后,你发给用户一个COOKIE来标记用户已登录,那完蛋了。。
坏人只要分析出这个COOKIE的格式,用任何账号名都能编造出来,还玩毛啊。。
只要客户端能直接触碰的东西都是不安全的。
------解决方案--------------------
那么你如何在大量的缓存数据中删去已被删除的记录的相关内容呢?
特别是 每次查询数据库都涉及到大量的联合、笛卡尔积等操作的话 结果集的内容可能出现很大的变化(与被删除记录相关的联合、笛卡尔积部分都不存在了)
------解决方案--------------------
再者说 SESSION、COOKIE 是属于用户私有的
而删除记录是公有的事件,你总不能说甲删除记录时对乙就无效吧
假定现在有一万个用户在线,你打算如何去更新他们的缓存呢?

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