Laravel5.3 流程粗粒度分析之bootstrap

从laravel入口文件index里面外面不难定位到Illuminate\Foundation\Http\Kernel的handle方法，同样也不难发现handle方法的核心是

$response = $this->sendRequestThroughRouter($request);

继续跟踪这个方法

/**
     * Send the given request through the middleware / router.
     *
     * @param  \Illuminate\Http\Request  $request
     * @return \Illuminate\Http\Response
     */
    protected function sendRequestThroughRouter($request)
    {
        $this->app->instance('request', $request);

        Facade::clearResolvedInstance('request');

        $this->bootstrap();

        return (new Pipeline($this->app))
                    ->send($request)
                    ->through($this->app->shouldSkipMiddleware() ? [] : $this->middleware)
                    ->then($this->dispatchToRouter());
    }

今天我们要讨论的就是方法中的$this->bootstrap();

/**
     * Bootstrap the application for HTTP requests.
     *
     * @return void
     */
    public function bootstrap()
    {
        if (! $this->app->hasBeenBootstrapped()) {
            $this->app->bootstrapWith($this->bootstrappers());
        }
    }

首先，我们先确定这个方法中的$this->app是类Illuminate\Foundation\Application以及$this->bootstrappers()如下所示数组

protected $bootstrappers = [
        'Illuminate\Foundation\Bootstrap\DetectEnvironment',
        'Illuminate\Foundation\Bootstrap\LoadConfiguration',
        'Illuminate\Foundation\Bootstrap\ConfigureLogging',
        'Illuminate\Foundation\Bootstrap\HandleExceptions',
        'Illuminate\Foundation\Bootstrap\RegisterFacades',
        'Illuminate\Foundation\Bootstrap\RegisterProviders',
        'Illuminate\Foundation\Bootstrap\BootProviders',
    ];

那么接下来我们查看$this->app->bootstrapWith($this->bootstrappers())

/**
     * Run the given array of bootstrap classes.
     *
     * @param  array  $bootstrappers
     * @return void
     */
    public function bootstrapWith(array $bootstrappers)
    {
        $this->hasBeenBootstrapped = true;

        foreach ($bootstrappers as $bootstrapper) {
            $this['events']->fire('bootstrapping: '.$bootstrapper, [$this]);

            $this->make($bootstrapper)->bootstrap($this);

            $this['events']->fire('bootstrapped: '.$bootstrapper, [$this]);
        }

    }

因为是粗粒度分析，我们同样只看这个方法的核心$this->make($bootstrapper)->bootstrap($this)，$this->make($bootstrapper)这个我们简单的理解为new $bootstrapper即可，所以这句代码的意思就是将上面$bootstrappers数组里面的每个类实例化并调用他们的bootstrap方法，那么上面那些类都是干什么的呢，其实从类的名字也可以猜出大概的意思了。

Illuminate\Foundation\Bootstrap\DetectEnvironment::bootstrap，从名字看，像是检查环境，具体代码如下：

/**
     * Bootstrap the given application.
     *
     * @param  \Illuminate\Contracts\Foundation\Application  $app
     * @return void
     */
    public function bootstrap(Application $app)
    {
        if (! $app->configurationIsCached()) {
            $this->checkForSpecificEnvironmentFile($app);

            try {
　　　　　　　　　　//$app->environmentPath()默认是我们的basePath，$app->environmentFile()默认是根目录里面的.env文件
                (new Dotenv($app->environmentPath(), $app->environmentFile()))->load();
            } catch (InvalidPathException $e) {
                //
            }
        }
    }

Illuminate\Foundation\Bootstrap\LoadConfiguration::bootstrap从名字看，像是加载配置，代码如下

/**
     * Bootstrap the given application.
     *
     * @param  \Illuminate\Contracts\Foundation\Application  $app
     * @return void
     */
    public function bootstrap(Application $app)
    {
        $items = [];

        // First we will see if we have a cache configuration file. If we do, we'll load
        // the configuration items from that file so that it is very quick. Otherwise
        // we will need to spin through every configuration file and load them all.
        if (file_exists($cached = $app->getCachedConfigPath())) {
            $items = require $cached;

            $loadedFromCache = true;
        }

        $app->instance('config', $config = new Repository($items));

        // Next we will spin through all of the configuration files in the configuration
        // directory and load each one into the repository. This will make all of the
        // options available to the developer for use in various parts of this app.
        if (! isset($loadedFromCache)) {
            $this->loadConfigurationFiles($app, $config);
        }

        $app->detectEnvironment(function () use ($config) {
            return $config->get('app.env', 'production');
        });

        date_default_timezone_set($config['app.timezone']);

        mb_internal_encoding('UTF-8');
    }

Illuminate\Foundation\Bootstrap\ConfigureLogging::bootstrap从名字看，像是配置日志，代码如下

/**
     * Bootstrap the given application.
     *
     * @param  \Illuminate\Contracts\Foundation\Application  $app
     * @return void
     */
    public function bootstrap(Application $app)
    {
　　　　　//大概就是默认使用Monolog作为日志记录
        $log = $this->registerLogger($app);

        // If a custom Monolog configurator has been registered for the application
        // we will call that, passing Monolog along. Otherwise, we will grab the
        // the configurations for the log system and use it for configuration.
        if ($app->hasMonologConfigurator()) {
            call_user_func(
                $app->getMonologConfigurator(), $log->getMonolog()
            );
        } else {
            $this->configureHandlers($app, $log);
        }
    }

    /**
     * Register the logger instance in the container.
     *
     * @param  \Illuminate\Contracts\Foundation\Application  $app
     * @return \Illuminate\Log\Writer
     */
    protected function registerLogger(Application $app)
    {
        $app->instance('log', $log = new Writer(
            new Monolog($app->environment()), $app['events'])
        );

        return $log;
    }

Illuminate\Foundation\Bootstrap\HandleExceptions::bootstrap看名字，像是处理异常，代码如下

 /**
     * Bootstrap the given application.
     *
     * @param  \Illuminate\Contracts\Foundation\Application  $app
     * @return void
     */
    public function bootstrap(Application $app)
    {
        $this->app = $app;

        error_reporting(-1);

        set_error_handler([$this, 'handleError']);

        set_exception_handler([$this, 'handleException']);

        register_shutdown_function([$this, 'handleShutdown']);

        if (! $app->environment('testing')) {
            ini_set('display_errors', 'Off');
        }
    }

Illuminate\Foundation\Bootstrap\RegisterFacades::bootstrap看名字像是注册Facades，代码如下，config目录下app配置的aliases配置就是在这里加载的

/**
     * Bootstrap the given application.
     *
     * @param  \Illuminate\Contracts\Foundation\Application  $app
     * @return void
     */
    public function bootstrap(Application $app)
    {
        Facade::clearResolvedInstances();

        Facade::setFacadeApplication($app);

        AliasLoader::getInstance($app->make('config')->get('app.aliases', []))->register();
    }

Illuminate\Foundation\Bootstrap\RegisterProviders::bootstrap看名字像是注册Providers，代码如下，config目录下app配置的providers配置就是在这里注册的

/**
     * Bootstrap the given application.
     *
     * @param  \Illuminate\Contracts\Foundation\Application  $app
     * @return void
     */
    public function bootstrap(Application $app)
    {
        $app->registerConfiguredProviders();
    }

Illuminate\Foundation\Bootstrap\BootProviders::bootstrap看名字像是启动Providers，代码如下，其实就是执行上面注册的Providers数组中各个Provide的boot方法

/**
     * Bootstrap the given application.
     *
     * @param  \Illuminate\Contracts\Foundation\Application  $app
     * @return void
     */
    public function bootstrap(Application $app)
    {
        $app->boot();
    }

/**
     * Boot the application's service providers.
     *
     * @return void
     */
    public function boot()
    {
        if ($this->booted) {
            return;
        }

        // Once the application has booted we will also fire some "booted" callbacks
        // for any listeners that need to do work after this initial booting gets
        // finished. This is useful when ordering the boot-up processes we run.
        $this->fireAppCallbacks($this->bootingCallbacks);

        array_walk($this->serviceProviders, function ($p) {
            $this->bootProvider($p);
        });

        $this->booted = true;

        $this->fireAppCallbacks($this->bootedCallbacks);
    }

我们经常安装一个扩展功能的时候需要去config里面的app.php的providers和aliases里面添加一些东西，通过以上的大概流程分析，我们就知道laravel是怎么处理这些东西的。