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HomeBackend DevelopmentPHP Tutorial将Session写入数据库是不是PHP原来的session完全就被自己替代了,相当于自己实现了session?

我看见很多都将session写入数据库。如果将session写入数据库,是不是相当于自己实现了数据库的session?原来自带的就失效了?

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我看见很多都将session写入数据库。如果将session写入数据库,是不是相当于自己实现了数据库的session?原来自带的就失效了?

这个问题我觉得首先要先明确到底什么是session,个人觉得session是一种实现,跟cookie性质不太一样。

举例登录 http://segmentfault.com/

  • 登录成功的时候服务器会生成一个类似diM4og.6c3c602eff435b68a0e2aeca90254482.a 的随机字符串,并将这个字符串与我的id(1030000000093602)关联起来存储在 服务器端 ,这样服务器端就知道 diM4og.6c3c602eff435b68a0e2aeca90254482.a 这个字符串属于哪个用户了。

    当然存储方式就随意选择了,以文件形式存储、数据库、redis、memcached

  • 同时会在用户登录成功后将 diM4og.6c3c602eff435b68a0e2aeca90254482.a 这个字符串以cookie的形式发送给客户端浏览器。 以 sf 为例,这个字符串存储在一个名为 sfsess 的cookie中。

  • 这样,登录后的每次访问,服务器端都会从客户端发来的cookie中读取中这个字符串,在服务器端查询是否有这个字符串的登录记录,有的话根据与之关联的 id 显示用户已登录。

这就是 session 的实现原理,python,java做的网站也一样,都是这个道理


下面说下PHP自带的 $_SESSION ,在我们用这句代码的时候,其实php同样做了上面的事情,只不过它是自动的,不用考虑具体实现。php服务器端存储session字符串是以文件形式存储的,客户端的cookie名是 PHPSESSION ,session过期什么的都由php自动管理了,当然cookie名称和过期时间等都可以通过配置php更改。

这就是php的优点,其实语言需要单独实现的session模块它一句代码搞定了。当然这也是它的缺点,使我们难以理解session的具体概念以及实现原理。

我看见很多都将session写入数据库。如果将session写入数据库,是不是相当于自己实现了数据库的session?原来自带的就失效了?

所以并不存在自带的失不失交的问题,只是以更屌的方式自己实现了session的验证而已,抛开了php的傻瓜代码。

另:sf 应该用的 redis 存储,Typecho用的数据库存储,楼主可以参考一下。

只是更改了session存放的地方,session还存在,只是从数据库里调用。

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