Laravel框架下路由的使用（源码解析）

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前言

我的解析文章并非深层次多领域的解析攻略。但是参考着开发文档看此类文章会让你在日常开发中更上一层楼。

废话不多说，我们开始本章的讲解。

入口

Laravel启动后，会先加载服务提供者、中间件等组件，在查找路由之前因为我们使用的是门面，所以先要查到Route的实体类。

注册

第一步当然还是通过服务提供者，因为这是laravel启动的关键，在 RouteServiceProvider 内加载路由文件。

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protected function mapApiRoutes() {     Route::prefix('api')          ->middleware('api')          ->namespace($this->namespace)  // 设置所处命名空间          ->group(base_path('routes/api.php'));  //所得路由文件绝对路径 }

首先require是不可缺少的。因路由文件中没有命名空间。 Illuminate\Routing\Router 下方法

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

随后通过路由找到指定方法,依旧是 Illuminate\Routing\Router 内有你所使用的所有路由相关方法，例如get、post、put、patch等等，他们都调用了统一的方法 addRoute

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

之后通过 Illuminate\Routing\RouteCollection addToCollections 方法添加到集合中

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protected function addToCollections($route) {     $domainAndUri = $route->getDomain().$route->uri();     foreach ($route->methods() as $method) {         $this->routes[$method][$domainAndUri] = $route;     }     $this->allRoutes[$method.$domainAndUri] = $route; }

添加后的结果如下图所示

调用

通过 Illuminate\Routing\Router 方法开始运行路由实例化的逻辑

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protected function runRoute(Request $request, Route $route) {     $request->setRouteResolver(function () use ($route) {                  return $route;     });     $this->events->dispatch(new Events\RouteMatched($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() // 此处调用run方法                         );                     }); }

在 Illuminate\Routing\Route 下 run 方用于执行控制器的方法

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public function run() {     $this->container = $this->container ?: new Container;     try {         if ($this->isControllerAction()) {             return $this->runController(); //运行一个路由并作出响应         }                      return $this->runCallable();     } catch (HttpResponseException $e) {         return $e->getResponse();     } }

从上述方法内可以看出 runController 是运行路由的关键,方法内运行了一个调度程序，将控制器 $this->getController() 和控制器方法 $this->getControllerMethod() 传入到 dispatch 调度方法内

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

这里注意 getController() 才是真正的将控制器实例化的方法

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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, '\\')); // 交给容器进行反射     }     return $this->controller; }

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实例化

依旧通过反射加载路由指定的控制器,这个时候build的参数$concrete = App\Api\Controllers\XxxController

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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); }

这时将返回控制器的实例，下面将通过url访问指定方法，一般控制器都会继承父类 Illuminate\Routing\Controller ,laravel为其设置了别名 BaseController

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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通过controller继承的callAction去调用子类的指定方法，也就是我们希望调用的自定义方法。

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