上次说了provider，那么这次来说说facade
首先是启动的源头，从laravel的kernel类中的$bootstrappers 数组，我们可以看到它的一些系统引导方法，其中的RegisterFacades便是用来注册facade门面类的了。
protected $bootstrappers = [ \Illuminate\Foundation\Bootstrap\LoadEnvironmentVariables::class, \Illuminate\Foundation\Bootstrap\LoadConfiguration::class, \Illuminate\Foundation\Bootstrap\HandleExceptions::class, \Illuminate\Foundation\Bootstrap\RegisterFacades::class, \Illuminate\Foundation\Bootstrap\RegisterProviders::class, \Illuminate\Foundation\Bootstrap\BootProviders::class, ];
同样是有一个register类，通过这个类进行别名等注册操作
namespace Illuminate\Foundation\Bootstrap; use Illuminate\Foundation\AliasLoader; use Illuminate\Support\Facades\Facade; use Illuminate\Foundation\PackageManifest; use Illuminate\Contracts\Foundation\Application; class RegisterFacades { /** * Bootstrap the given application. * * @param \Illuminate\Contracts\Foundation\Application $app * @return void */ public function bootstrap(Application $app) { //清除facade所有已绑定实例 Facade::clearResolvedInstances(); //将app存入对象 Facade::setFacadeApplication($app); //将这些别名数组通过构造函数存入对象中 AliasLoader::getInstance(array_merge( //通过Illuminate\Config\Repository获取config/app.php中的aliases数组 $app->make(\'config\')->get(\'app.aliases\', []), //还记得最开始的博文中提到的那个包清单吗，这里也从中获取了它的aliases $app->make(PackageManifest::class)->aliases() //通过spl_autoload_register函数注册另一种自动加载函数 ))->register(); } }
public static function getInstance(array $aliases = []) { //注册时的实例是空的，会通过构造方法把刚刚传入的别名数组存入对象 if (is_null(static::$instance)) { return static::$instance = new static($aliases); } $aliases = array_merge(static::$instance->getAliases(), $aliases); static::$instance->setAliases($aliases); return static::$instance; } private function __construct($aliases) { $this->aliases = $aliases; }
public function register() { if (! $this->registered) { $this->prependToLoaderStack(); $this->registered = true; } } /** * Prepend the load method to the auto-loader stack. * * @return void */ protected function prependToLoaderStack() { //最后通过自动加载函数将本对象中的load方法放入自动加载队列的前端，在我们通过类名调用方法时，会触发自动加载函数队列，会优先触发这个函数，查找到对应文件的路径然后加载相应文件 spl_autoload_register([$this, \'load\'], true, true); }
public function load($alias) { //若传入的命名空间不为当前facade数组内才会通过这个方法加载 if (static::$facadeNamespace && strpos($alias, static::$facadeNamespace) === 0) { $this->loadFacade($alias); return true; } //否则直接返回其别名 if (isset($this->aliases[$alias])) { return class_alias($this->aliases[$alias], $alias); } } /** * Load a real-time facade for the given alias. * * @param string $alias * @return void */ protected function loadFacade($alias) { require $this->ensureFacadeExists($alias); } /** * Ensure that the given alias has an existing real-time facade class. * * @param string $alias * @return string */ protected function ensureFacadeExists($alias) { //从缓存中返回路径 if (file_exists($path = storage_path(\'framework/cache/facade-\'.sha1($alias).\'.php\'))) { return $path; } file_put_contents($path, $this->formatFacadeStub( $alias, file_get_contents(__DIR__.\'/stubs/facade.stub\') )); return $path; }
由于laravel中composer的执行过程过于繁琐，这里就不做深究了。原理是一样的，通过别名找到命名空间的类名，再由composer的类名与文件路径映射关系，自动加载函数找到相应文件加载进来。
那么我们来自定义一个门面类试一下
1、新建一个facade类，这里返回的test是上一篇博客中定义的对象
namespace App\Facades; use Illuminate\Support\Facades\Facade; class Test extends Facade { protected static function getFacadeAccessor() { return \'App\Contracts\Test\'; } }
2、将它添加到config/app.php的aliases别名数组中
\'aliases\' => [ \'App\' => Illuminate\Support\Facades\App::class, \'Artisan\' => Illuminate\Support\Facades\Artisan::class, \'Auth\' => Illuminate\Support\Facades\Auth::class, \'Blade\' => Illuminate\Support\Facades\Blade::class, \'Broadcast\' => Illuminate\Support\Facades\Broadcast::class, \'Bus\' => Illuminate\Support\Facades\Bus::class, \'Cache\' => Illuminate\Support\Facades\Cache::class, \'Config\' => Illuminate\Support\Facades\Config::class, \'Cookie\' => Illuminate\Support\Facades\Cookie::class, \'Crypt\' => Illuminate\Support\Facades\Crypt::class, \'DB\' => Illuminate\Support\Facades\DB::class, \'Eloquent\' => Illuminate\Database\Eloquent\Model::class, \'Event\' => Illuminate\Support\Facades\Event::class, \'File\' => Illuminate\Support\Facades\File::class, \'Gate\' => Illuminate\Support\Facades\Gate::class, \'Hash\' => Illuminate\Support\Facades\Hash::class, \'Lang\' => Illuminate\Support\Facades\Lang::class, \'Log\' => Illuminate\Support\Facades\Log::class, \'Mail\' => Illuminate\Support\Facades\Mail::class, \'Notification\' => Illuminate\Support\Facades\Notification::class, \'Password\' => Illuminate\Support\Facades\Password::class, \'Queue\' => Illuminate\Support\Facades\Queue::class, \'Redirect\' => Illuminate\Support\Facades\Redirect::class, \'Redis\' => Illuminate\Support\Facades\Redis::class, \'Request\' => Illuminate\Support\Facades\Request::class, \'Response\' => Illuminate\Support\Facades\Response::class, \'Route\' => Illuminate\Support\Facades\Route::class, \'Schema\' => Illuminate\Support\Facades\Schema::class, \'Session\' => Illuminate\Support\Facades\Session::class, \'Storage\' => Illuminate\Support\Facades\Storage::class, \'URL\' => Illuminate\Support\Facades\URL::class, \'Validator\' => Illuminate\Support\Facades\Validator::class, \'View\' => Illuminate\Support\Facades\View::class, //刚刚新建的facades \'Test\' => \App\Facades\Test::class, ],
3、在路由文件中调用它
Route::any(\'/index\', function (){ Test::doing(); });
我们会发现，即使我们没有通过app对象进行make也没有任何命名空间的引入，它就这样被调用了。
如果是在类中调用，那么就要麻烦一些了，需要ues这个别名，注意这一点
namespace App\Http\Controllers; use Illuminate\Http\Request; //use App\Contracts\Test; //注意这里只引入了别名，由于命名空间冲突，所以我注释了其他部分 use Test; class IndexController extends Controller { // public function __construct(Test $test) // { // $this->test = $test; // } public function index(Test $test) { Test::doing(); // app()->make(\'App\Contracts\Test\')->doing(); // echo \'<br>\'; // // //只有通过构造方法进行自动加载依赖的方式才能触发契约的when绑定 // $this->test->doing(); // // echo \'<br>\'; // //因为laravel中的上下文绑定只能具体到类，所以这里的$test实例依然为普通绑定 // $test->doing(); } }
通过这个demo的实践，facade还是比较简单的。