摘要：入口啟動后，會先加載服務提供者中間件等組件，在查找路由之前因為我們使用的是門面，所以先要查到的實體類。注冊第一步當然還是通過服務提供者，因為這是啟動的關鍵，在內加載路由文件。因路由文件中沒有命名空間。

我的解析文章并非深層次多領域的解析攻略。但是參考著開發文檔看此類文章會讓你在日常開發中更上一層樓。

廢話不多說，我們開始本章的講解。

Laravel啟動后，會先加載服務提供者、中間件等組件，在查找路由之前因為我們使用的是門面，所以先要查到Route的實體類。

第一步當然還是通過服務提供者，因為這是laravel啟動的關鍵，在 RouteServiceProvider 內加載路由文件。

protected function mapApiRoutes()
{
    Route::prefix("api")
         ->middleware("api")
         ->namespace($this->namespace)  // 設置所處命名空間
         ->group(base_path("routes/api.php"));  //所得路由文件絕對路徑
}

首先require是不可缺少的。因路由文件中沒有命名空間。 IlluminateRoutingRouter 下方法

protected function loadRoutes($routes)
{
    if ($routes instanceof Closure) {
        $routes($this);
    } else {
        $router = $this;

        require $routes;
    }
}

隨后通過路由找到指定方法,依舊是 IlluminateRoutingRouter 內有你所使用的所有路由相關方法，例如get、post、put、patch等等，他們都調用了統一的方法 addRoute

public function addRoute($methods, $uri, $action)
{
    return $this->routes->add($this->createRoute($methods, $uri, $action));
}

之后通過 IlluminateRoutingRouteCollection addToCollections 方法添加到集合中

protected function addToCollections($route)
{
    $domainAndUri = $route->getDomain().$route->uri();

    foreach ($route->methods() as $method) {
        $this->routes[$method][$domainAndUri] = $route;
    }

    $this->allRoutes[$method.$domainAndUri] = $route;
}

添加后的結果如下圖所示

通過 IlluminateRoutingRouter 方法開始運行路由實例化的邏輯

protected function runRoute(Request $request, Route $route)
{
    $request->setRouteResolver(function () use ($route) {
        
        return $route;
    });
    $this->events->dispatch(new EventsRouteMatched($route, $request));

    return $this->prepareResponse($request,
        $this->runRouteWithinStack($route, $request)
    );
}
....
protected function runRouteWithinStack(Route $route, Request $request)
{
    $shouldSkipMiddleware = $this->container->bound("middleware.disable") &&
                            $this->container->make("middleware.disable") === true;

    $middleware = $shouldSkipMiddleware ? [] : $this->gatherRouteMiddleware($route);

    return (new Pipeline($this->container))
                    ->send($request)
                    ->through($middleware)
                    ->then(function ($request) use ($route) {
                        return $this->prepareResponse(
                            $request, $route->run() // 此處調用run方法
                        );
                    });
}

在 IlluminateRoutingRoute 下 run 方用于執行控制器的方法

public function run()
{
    $this->container = $this->container ?: new Container;

    try {
        if ($this->isControllerAction()) { 
            return $this->runController(); //運行一個路由并作出響應
        }
            
        return $this->runCallable();
    } catch (HttpResponseException $e) {
        return $e->getResponse();
    }
}

從上述方法內可以看出 runController 是運行路由的關鍵,方法內運行了一個調度程序，將控制器 $this->getController() 和控制器方法 $this->getControllerMethod() 傳入到 dispatch 調度方法內

protected function runController()
{
    
    return $this->controllerDispatcher()->dispatch(
        $this, $this->getController(), $this->getControllerMethod()
    );
}

這里注意 getController() 才是真正的將控制器實例化的方法

public function getController()
{
    
    if (! $this->controller) {
        $class = $this->parseControllerCallback()[0]; // 0=>控制器 xxController 1=>方法名 index
        $this->controller = $this->container->make(ltrim($class, "")); // 交給容器進行反射
    }

    return $this->controller;
}

依舊通過反射加載路由指定的控制器,這個時候build的參數$concrete = AppApiControllersXxxController

public function build($concrete)
{
    // If the concrete type is actually a Closure, we will just execute it and
    // hand back the results of the functions, which allows functions to be
    // used as resolvers for more fine-tuned resolution of these objects.
    if ($concrete instanceof Closure) {
        return $concrete($this, $this->getLastParameterOverride());
    }
    
    $reflector = new ReflectionClass($concrete);
    // If the type is not instantiable, the developer is attempting to resolve
    // an abstract type such as an Interface of Abstract Class and there is
    // no binding registered for the abstractions so we need to bail out.
    if (! $reflector->isInstantiable()) {
        return $this->notInstantiable($concrete);
    }
    
        
    $this->buildStack[] = $concrete;

    $constructor = $reflector->getConstructor();
    // If there are no constructors, that means there are no dependencies then
    // we can just resolve the instances of the objects right away, without
    // resolving any other types or dependencies out of these containers.
    if (is_null($constructor)) {
    
            array_pop($this->buildStack);
    
            return new $concrete;
    }

    $dependencies = $constructor->getParameters();
    // Once we have all the constructor"s parameters we can create each of the
    // dependency instances and then use the reflection instances to make a
    // new instance of this class, injecting the created dependencies in.
    $instances = $this->resolveDependencies(
        $dependencies
    );

    array_pop($this->buildStack);
    
    return $reflector->newInstanceArgs($instances);
}

這時將返回控制器的實例，下面將通過url訪問指定方法，一般控制器都會繼承父類 IlluminateRoutingController ,laravel為其設置了別名 BaseController

public function dispatch(Route $route, $controller, $method)
{
    
    $parameters = $this->resolveClassMethodDependencies(
        $route->parametersWithoutNulls(), $controller, $method
    );

    if (method_exists($controller, "callAction")) {

            return $controller->callAction($method, $parameters);
    }
        
    return $controller->{$method}(...array_values($parameters));
}

Laravel通過controller繼承的callAction去調用子類的指定方法，也就是我們希望調用的自定義方法。

public function callAction($method, $parameters)
{
    return call_user_func_array([$this, $method], $parameters);
}

感謝你看到這里，本篇文章源碼解析靠個人理解。如有出入請拍磚。

希望本篇文章可以幫到你。謝謝