Laravel 源码阅读之二：Illuminate\Foundation\Application 类初始化分析

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//实例化Application类，传入参数为项目目录路径，如：/home/vagrant/code/Laravel
$app = new Illuminate\Foundation\Application(
    realpath(__DIR__.'/../')
);

//绑定类的实现到接口，使得依赖注入是`Illuminate\Contracts\Http\Kerne`接口类
//可以得到`App\Http\Kernel::class`类，另外两个绑定同理。
$app->singleton(
    Illuminate\Contracts\Http\Kernel::class,
    App\Http\Kernel::class
);
$app->singleton(
    Illuminate\Contracts\Console\Kernel::class,
    App\Console\Kernel::class
);
$app->singleton(
    Illuminate\Contracts\Debug\ExceptionHandler::class,
    App\Exceptions\Handler::class
);
//返回实例
return $app;Copy

public function __construct($basePath = null)
    {
        if ($basePath) {
            //（A）路径绑定
            //设置basePath，即项目目录（非站点根目录），
            //其路径形如：/home/vagrant/code/Laravel
            //setBasePath方法内部还调用了bindPathsInContainer方法，其方法分析见（A）部分
            $this->setBasePath($basePath);
        }
        //（B）基础绑定
        $this->registerBaseBindings();
        //（C）基础服务提供者绑定，结果绑定在$this->serverProvider中
        $this->registerBaseServiceProviders();
        //（D）核心别名绑定，结果绑定在$this->aliases和$this->abstractAliases中
        $this->registerCoreContainerAliases();
    }Copy

protected function bindPathsInContainer()
{
    //path()方法用于给项目目录路径后缀'/app'+传入的$path,这里$path=''，
    //最后得到项目的app路径
    $this->instance('path', $this->path());
    $this->instance('path.base', $this->basePath());
    $this->instance('path.lang', $this->langPath());
    $this->instance('path.config', $this->configPath());
    $this->instance('path.public', $this->publicPath());
    $this->instance('path.storage', $this->storagePath());
    $this->instance('path.database', $this->databasePath());
    $this->instance('path.resources', $this->resourcePath());
    $this->instance('path.bootstrap', $this->bootstrapPath());
}Copy

public function instance($abstract, $instance)
{
    //移除类的标识的别名（如果有的话）
    $this->removeAbstractAlias($abstract);

    //bound()方法的实现只有这句：
    //return isset($this->deferredServices[$abstract]) || parent::bound($abstract);
    //判断是否有绑定
    $isBound = $this->bound($abstract);
    //去掉对应别名
    unset($this->aliases[$abstract]);

    //保存传入的值到instances变量
    $this->instances[$abstract] = $instance;

    if ($isBound) {
        $this->rebound($abstract);
    }

    return $instance;
}Copy

protected function registerBaseBindings()
{
    //B-1
    static::setInstance($this);
    //B-2
    $this->instance('app', $this);
    //与B-2类似
    $this->instance(Container::class, $this);
    //B-3
    $this->instance(PackageManifest::class, new PackageManifest(
        new Filesystem, $this->basePath(), $this->getCachedPackagesPath()
    ));
}Copy

 public static function setInstance(ContainerContract $container = null)
{
    return static::$instance = $container;
}Copy

protected function registerBaseServiceProviders()
{
    //C-1 注册事件服务
    $this->register(new EventServiceProvider($this));
    //C-2 注册日志服务
    $this->register(new LogServiceProvider($this));
    //C-3 注册路由服务
    $this->register(new RoutingServiceProvider($this));
}Copy

public function __construct($app)
{
    $this->app = $app;
}Copy

public function register($provider, $force = false)
{
    //C-4
    //假设$provider='Illuminate\Events\EventServiceProvider'类的实例
    //这里$registered=null
    if (($registered = $this->getProvider($provider)) && ! $force) {
        return $registered;
    }

    //C-5
    //$provider不是字符串，是一个类的实例
    if (is_string($provider)) {
        $provider = $this->resolveProvider($provider);
    }
    //判断该类是否存在‘register’方法，有则的调用它
    if (method_exists($provider, 'register')) {
        $provider->register();
    }

    if (property_exists($provider, 'bindings')) {
        foreach ($provider->bindings as $key => $value) {
            $this->bind($key, $value);
        }
    }

    if (property_exists($provider, 'singletons')) {
        foreach ($provider->singletons as $key => $value) {
            $this->singleton($key, $value);
        }
    }

    $this->markAsRegistered($provider);

    // If the application has already booted, we will call this boot method on
    // the provider class so it has an opportunity to do its boot logic and
    // will be ready for any usage by this developer's application logic.
    if ($this->booted) {
        $this->bootProvider($provider);
    }

    return $provider;
}Copy

public function getProvider($provider)
{
    //判断是否有服务提供者，有则返回该类的标识，没有则返回null
    return array_values($this->getProviders($provider))[0] ?? null;
}Copy

public function getProviders($provider)
{
    //$name='Illuminate\Events\EventServiceProvider'
    $name = is_string($provider) ? $provider : get_class($provider);
    //判断$this->serviceProviders的每一个元素是否是$name的实例，是则保留
    return Arr::where($this->serviceProviders, function ($value) use ($name) {
        return $value instanceof $name;
    });
}Copy

public function registerCoreContainerAliases()
    {
        foreach ([
            'app'                  => [\Illuminate\Foundation\Application::class, \Illuminate\Contracts\Container\Container::class, \Illuminate\Contracts\Foundation\Application::class,  \Psr\Container\ContainerInterface::class],
            'auth'                 => [\Illuminate\Auth\AuthManager::class, \Illuminate\Contracts\Auth\Factory::class],
            'auth.driver'          => [\Illuminate\Contracts\Auth\Guard::class],
            'blade.compiler'       => [\Illuminate\View\Compilers\BladeCompiler::class],
           .
           .
           .
        ] as $key => $aliases) {
            foreach ($aliases as $alias) {
                $this->alias($key, $alias);
            }
        }Copy

public function alias($abstract, $alias)
    {
        $this->aliases[$alias] = $abstract;

        $this->abstractAliases[$abstract][] = $alias;
    }Copy