Laravel-海贼王系列第十三章，路由和amp;控制器

路由

一个请求如何跨过山和大海来到控制器的地盘。

注册路由

这块代码是在 Application 的构造函数中加载的

public function __construct($basePath = null)
{
    ...
    $this->registerBaseServiceProviders();
    ...
}

protected function registerBaseServiceProviders()
{
    ...
    $this->register(new RoutingServiceProvider($this));
    ...
}

展开完整的服务提供者

<?php

namespace Illuminate\Routing;

use Illuminate\Support\ServiceProvider;
use Psr\Http\Message\ResponseInterface;
use Zend\Diactoros\Response as PsrResponse;
use Psr\Http\Message\ServerRequestInterface;
use Symfony\Bridge\PsrHttpMessage\Factory\DiactorosFactory;
use Illuminate\Contracts\View\Factory as ViewFactoryContract;
use Illuminate\Contracts\Routing\ResponseFactory as ResponseFactoryContract;
use Illuminate\Routing\Contracts\ControllerDispatcher as ControllerDispatcherContract;

class RoutingServiceProvider extends ServiceProvider
{

    public function register()
    {
        $this->registerRouter();
        $this->registerUrlGenerator();
        $this->registerRedirector();
        $this->registerPsrRequest();
        $this->registerPsrResponse();
        $this->registerResponseFactory();
        $this->registerControllerDispatcher();
    }

    protected function registerRouter()
    {
        $this->app->singleton('router', function ($app) {
            return new Router($app['events'], $app);
        });
    }

    protected function registerUrlGenerator()
    {
        $this->app->singleton('url', function ($app) {
            $routes = $app['router']->getRoutes();

            $app->instance('routes', $routes);

            $url = new UrlGenerator(
                $routes, $app->rebinding(
                    'request', $this->requestRebinder()
                ), $app['config']['app.asset_url']
            );

            $url->setSessionResolver(function () {
                return $this->app['session'];
            });

            $url->setKeyResolver(function () {
                return $this->app->make('config')->get('app.key');
            });

            $app->rebinding('routes', function ($app, $routes) {
                $app['url']->setRoutes($routes);
            });

            return $url;
        });
    }

    protected function requestRebinder()
    {
        return function ($app, $request) {
            $app['url']->setRequest($request);
        };
    }

    protected function registerRedirector()
    {
        $this->app->singleton('redirect', function ($app) {
            $redirector = new Redirector($app['url']);

            if (isset($app['session.store'])) {
                $redirector->setSession($app['session.store']);
            }

            return $redirector;
        });
    }

    protected function registerPsrRequest()
    {
        $this->app->bind(ServerRequestInterface::class, function ($app) {
            return (new DiactorosFactory)->createRequest($app->make('request'));
        });
    }

    protected function registerPsrResponse()
    {
        $this->app->bind(ResponseInterface::class, function () {
            return new PsrResponse;
        });
    }

    protected function registerResponseFactory()
    {
        $this->app->singleton(ResponseFactoryContract::class, function ($app) {
            return new ResponseFactory($app[ViewFactoryContract::class], $app['redirect']);
        });
    }

    protected function registerControllerDispatcher()
    {
        $this->app->singleton(ControllerDispatcherContract::class, function ($app) {
            return new ControllerDispatcher($app);
        });
    }
}

后面在使用中会涉及这里注册的对象，红框内就是注册的绑定关系。

启动在这里并没有完成，这仅仅是启动系统的基础路由，在 app.php 中还有一个路由服务提供者 RouteServiceProvider

<?php

namespace App\Providers;

use Illuminate\Support\Facades\Route;
use Illuminate\Foundation\Support\Providers\RouteServiceProvider as ServiceProvider;

class RouteServiceProvider extends ServiceProvider
{
    protected $namespace = 'App\Http\Controllers';

    public function boot()
    {
        // "boot() 方法是在服务提供者所有 register() 方法执行完成之后在统一执行的"
        
        // "这段代码最后会调用 $this->map();"
        parent::boot();
    }

    public function map()
    {
        $this->mapApiRoutes();

        $this->mapWebRoutes();

    }

    // "这一块的逻辑非常复杂就不展开了，主要功能就是优先加载 cache/routes.php，如果不存在
       则从给定的路径加载路由文件"
   
    protected function mapWebRoutes()
    {
        Route::middleware('web')
             ->namespace($this->namespace)
             ->group(base_path('routes/web.php')); 
    }

    protected function mapApiRoutes()
    {
        Route::prefix('api')
             ->middleware('api')
             ->namespace($this->namespace)
             ->group(base_path('routes/api.php'));
    }
}

内核启动

注册完成之后就是开始处理，是从内核的 handle() 方法开始处理请求

protected function sendRequestThroughRouter($request)
{
    ...

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

这里会在运行完中间件之后最后运行 $this->dispatchToRouter() 这个方法。

$this->router 对象是在内核的构造函数注入的 \Illuminate\Routing\Router 对象

protected function dispatchToRouter()
{
    return function ($request) {
        $this->app->instance('request', $request);
        
        return $this->router->dispatch($request);
    };
}

那么我们接着看 dispatch 方法

public function dispatch(Request $request)
{
    $this->currentRequest = $request;

    return $this->dispatchToRoute($request);
}

转发一个请求给路由返回一个响应对象

public function dispatchToRoute(Request $request)
{
    return $this->runRoute($request, $this->findRoute($request));
}

找到路由

我的理解：router 代表路由器，route 则是代表一次路由的对象，

所有路由器的功能就是执行，派发路由对象。所以我们需要先通过请求来拿到一个路由对象

protected function findRoute($request)
{
    $this->current = $route = $this->routes->match($request);

    // "绑定最新的 $route 对象到容器"
    
    $this->container->instance(Route::class, $route);
    
    // "返回路由"
    return $route;
}

继续分析 $this->routes->match($request);,

这里的 $this->routes 是构造函数注入的 Illuminate\Routing\RouteCollection 对象

public function match(Request $request)
{

    $routes = $this->get($request->getMethod()); 

    $route = $this->matchAgainstRoutes($routes, $request);

    if (! is_null($route)) {
        return $route->bind($request);
    }

    $others = $this->checkForAlternateVerbs($request);

    if (count($others) > 0) {
        return $this->getRouteForMethods($request, $others);
    }

    throw new NotFoundHttpException;
}

$routes 对象这里面的值来自与路由缓存文件或者路由文件解析结果

继续看 $route = $this->matchAgainstRoutes($routes, $request); 执行结果从请求中匹配对应路由并返回

如果没有匹配的路由则使用请求方法以外的方法继续匹配

public static $verbs = ['GET', 'HEAD', 'POST', 'PUT', 'PATCH', 'DELETE', 'OPTIONS'];

protected function checkForAlternateVerbs($request)
{
    $methods = array_diff(Router::$verbs, [$request->getMethod()]);

    $others = [];

    foreach ($methods as $method) {
        if (! is_null($this->matchAgainstRoutes($this->get($method), $request, false))) {
            $others[] = $method;
        }
    }

    return $others;
}

执行完成返回 $other 数组，如果还是没有则抛出throw new NotFoundHttpException;

这里不详细叙述了，如果匹配成功我们将得到一个 Illuminate\Routing\Route 对象传递下去。

派发路由

当我们得到路由对象之后就是派发它了，根据给定的路由返回响应对象

protected function runRoute(Request $request, Route $route)
{
    // "将这个闭包设置到 request 对象的 $this->routeResolver 成员上"
    
    $request->setRouteResolver(function () use ($route) {
        return $route;
    });

    // "执行路由匹配的事件，框架刚启动的时候这里什么都不做"
    $this->events->dispatch(new Events\RouteMatched($route, $request));

    return $this->prepareResponse($request,
        $this->runRouteWithinStack($route, $request)
    );
}

获取响应

执行到这里就已经到了最后的部分了

return $this->prepareResponse($request,
        $this->runRouteWithinStack($route, $request)
    );

这个方法就是将 $request 和 $response 根据里面的属性封装好数据返回而已。

public function prepareResponse($request, $response)
{
    return static::toResponse($request, $response);
}

重点看 $this->runRouteWithinStack($route, $request) 这段话才是将请求传递到控制器关键！

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()
                        );
                    });
}

又到了这种用法，不理解执行逻辑请看第七章，

根据 Pipeline 的使用原理，我们在通过所有 $middleware

之后会将 $requeset 传递给闭包来结束

所以这是终点！

function ($request) use ($route) {
                        return $this->prepareResponse(
                            $request, $route->run()
                        );
                    }

刚才说过了 $this->prepareResponse() 这个方法没什么亮点就是

将请求和响应对象封装返回，所有我们应该知道了，$route->run() 将返回 response 对象！

控制器闪亮登场

来吧，经历了无数令人发指的封装希望后面一片坦途，run()

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

    try {
    
        if ($this->isControllerAction()) { 
            return $this->runController();
        }

        return $this->runCallable();
    } catch (HttpResponseException $e) {
        return $e->getResponse();
    }
}

总算看到了 runController() 方法了，想必路由跨过山和大海最总的归宿也到这儿了

$this->isControllerAction() 是判断路由是闭包还是字符串

如果是字符串向上图红框中的内容则执行

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

这里是调用 Illuminate\Routing\ControllerDispatcher 的 dispatch 方法

public function dispatch(Route $route, $controller, $method)
{
    // "从容器获取当前类构造函数依赖和方法依赖参数"
    $parameters = $this->resolveClassMethodDependencies(
        $route->parametersWithoutNulls(), $controller, $method
    );

    if (method_exists($controller, 'callAction')) {
        return $controller->callAction($method, $parameters);
    }

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

callAction 来自所有控制器基础的 Illuminate\Routing\Controller

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

没什么好讲的其实就是调用控制器对应的方法。

如果路由是闭包形式，则直接抽取路由对象中的闭包进行调用

protected function runCallable()
{
    $callable = $this->action['uses'];

    // "通过容器抽取依赖的参数传入闭包运行"
    return $callable(...array_values($this->resolveMethodDependencies(
        $this->parametersWithoutNulls(), new ReflectionFunction($this->action['uses'])
    )));
}

结语

总算结束了，Laravel 路由在启动阶段注册了非常多的类，

1.Application 构造阶段 $this->register(new RoutingServiceProvider($this));

2.Kernel handle() bootstrap() 阶段加载服务提供者的时候包含了 App\Providers\RouteServiceProvider::class,

这两个阶段注册加上加载的逻辑是非常复杂，但是目的也很简单从就是从路由文件转成路由对象的过程，没有力气分析进去。

其他的就是最后一直调用到控制器的过程，其中最后的 resolveClassMethodDependencies ， resolveMethodDependencies

也是非常值得研究的代码。

这篇好文章是转载于：学新通技术网