1. 云栖社区>
  2. PHP教程>
  3. 正文

Laravel 的 Session机制简介

作者:用户 来源:互联网 时间:2017-12-01 13:43:17

机制简介

Laravel 的 Session机制简介 - 摘要: 本文讲的是Laravel 的 Session机制简介, 前些天,为了解答一个问题,就去研究了Laravel的源码,讲讲我的收获:这个是问题源:http://segmentfault.com/q/1010000003776645?_ea=365137 本文讲的Laravel全部使用5.1版本。

前些天,为了解答一个问题,就去研究了Laravel的源码,讲讲我的收获:
这个是问题源:
http://segmentfault.com/q/1010000003776645?_ea=365137

本文讲的Laravel全部使用5.1版本。

我们首先看Laravel是如何创建Session组件的。
首先我们可以看见在Kernel.php中注册了StartSession这个类(这里不去讨论Laravel的DI和IoC),看下这个类是如何使用的。

Session Start

我们在这个类中的handle方法看到如下代码

public function handle($request, Closure $next){$this->sessionHandled = true;// If a session driver has been configured, we will need to start the session here// so that the data is ready for an application. Note that the Laravel sessions// do not make use of PHP "native" sessions in any way since they are crappy.if ($this->sessionConfigured()) {$session = $this->startSession($request);$request->setSession($session);}$response = $next($request);// Again, if the session has been configured we will need to close out the session// so that the attributes may be persisted to some storage medium. We will also// add the session identifier cookie to the application response headers now.if ($this->sessionConfigured()) {$this->storeCurrentUrl($request, $session);$this->collectGarbage($session);$this->addCookieToResponse($response, $session);}return $response;}

OK,一个典型的过滤器,在这个StartSession中获取Session的方法是getSession

Get Session

它使用了Laravel注入的SessionManager 这个类的完整限定名是:/Illuminate/Session/SessionManager

/** * Start the session for the given request. * * @param  /Illuminate/Http/Request  $request * @return /Illuminate/Session/SessionInterface */protected function startSession(Request $request){with($session = $this->getSession($request))->setRequestOnHandler($request);$session->start();return $session;}/** * Get the session implementation from the manager. * * @param  /Illuminate/Http/Request  $request * @return /Illuminate/Session/SessionInterface */public function getSession(Request $request){$session = $this->manager->driver();$session->setId($request->cookies->get($session->getName()));return $session;}

我们在这个函数中看到,它调用了SessionManagerdrive方法,drive方法是SessionManager的父类Manager中定义的,看到它的实现是这样的

/** * Get a driver instance. * * @param  string  $driver * @return mixed */public function driver($driver = null){$driver = $driver ?: $this->getDefaultDriver();// If the given driver has not been created before, we will create the instances// here and cache it so we can return it next time very quickly. If there is// already a driver created by this name, we'll just return that instance.if (! isset($this->drivers[$driver])) {$this->drivers[$driver] = $this->createDriver($driver);}return $this->drivers[$driver];}/** * Create a new driver instance. * * @param  string  $driver * @return mixed * * @throws /InvalidArgumentException */protected function createDriver($driver){$method = 'create'.ucfirst($driver).'Driver';// We'll check to see if a creator method exists for the given driver. If not we// will check for a custom driver creator, which allows developers to create// drivers using their own customized driver creator Closure to create it.if (isset($this->customCreators[$driver])) {return $this->callCustomCreator($driver);} elseif (method_exists($this, $method)) {return $this->$method();}throw new InvalidArgumentException("Driver [$driver] not supported.");}

也就是调用getDefaultDriver方法

/** * Get the default session driver name. * * @return string */public function getDefaultDriver(){return $this->app['config']['session.driver'];}

这里就是我们在app/config/session.php中定义的driver字段,获取这个字段后,我们可以从createDriver的源码看到,它实际上是调用createXXXXDriver的方式获取到driver的。

OK,我们看下最简单的File,也就是createFileDriver

/** * Create an instance of the file session driver. * * @return /Illuminate/Session/Store */protected function createFileDriver(){return $this->createNativeDriver();}/** * Create an instance of the file session driver. * * @return /Illuminate/Session/Store */protected function createNativeDriver(){$path = $this->app['config']['session.files'];return $this->buildSession(new FileSessionHandler($this->app['files'], $path));}/** * Build the session instance. * * @param  /SessionHandlerInterface  $handler * @return /Illuminate/Session/Store */protected function buildSession($handler){if ($this->app['config']['session.encrypt']) {return new EncryptedStore($this->app['config']['session.cookie'], $handler, $this->app['encrypter']);} else {return new Store($this->app['config']['session.cookie'], $handler);}}

这个Store就是我们Session的实体了,它的具体读写调用使用抽象的Handler进行,也就是说如果是读文件,就new FileHandler如果是Redis就是new RedisHandler实现readwrite即可。

Session ID

回到StartSession 这个类,我们再看getSession这个方法

 $session->setId($request->cookies->get($session->getName()));

了解Web的人都应该知道,session是根据cookie中存的key来区分不同的会话的,所以sessionId尤为重要,这里我们先不关心Cookie是如何读取,我们知道在这里读取了cookie中存放的SessionId就够了。

接下去看怎么加载数据

Data

依然是StartSession这个类,
我们看startSession这个方法,下一句调用的就是$session->start();,这句话是干嘛呢。经过前面的分析,我们知道$session已经是Store对象了,那么它的start方法如下:

public function start(){$this->loadSession();if (! $this->has('_token')) {$this->regenerateToken();}return $this->started = true;}/** * Load the session data from the handler. * * @return void */protected function loadSession(){$this->attributes = array_merge($this->attributes, $this->readFromHandler());foreach (array_merge($this->bags, [$this->metaBag]) as $bag) {$this->initializeLocalBag($bag);$bag->initialize($this->bagData[$bag->getStorageKey()]);}} /** * Read the session data from the handler. * * @return array */protected function readFromHandler(){$data = $this->handler->read($this->getId());if ($data) {$data = @unserialize($this->prepareForUnserialize($data));if ($data !== false && $data !== null && is_array($data)) {return $data;}}return [];}

依次调用了loadSessionreadFromHandler 好,可以看到从handler中调用了read方法,这个方法就是从我们之前定义的各种handler中读取数据了,它是个抽象方法,在子类中具体实现,然后返回给Store(存入到Store中的attributes数组中去了,到此为止,Session的初始化方法都结束了,

public function get($name, $default = null){return Arr::get($this->attributes, $name, $default);}

这个函数去读取Session中的数据了。

Summary

OK,Session整个初始化的过程总结下:

StartSession#handle -> StartSession#startSession -> StartSession#getSession -> SessionManager#getDefaultDriver -> SessionManager#createXXXHandler -> Store -> Store#setId -> Store#startSession

Laravel巧妙的使用了面向对象的接口方式,为我们提供了各种各样不同的存储方式,一旦我们了解了存储方式和加密规则,让不同的web容器进行Session共享的目的也可以达到~

以上是云栖社区小编为您精心准备的的内容,在云栖社区的博客、问答、公众号、人物、课程等栏目也有的相关内容,欢迎继续使用右上角搜索按钮进行搜索机制 简介 ,以便于您获取更多的相关知识。