laravel 入口

php 通过 symfony/http-foundation（http请求响应封装） 框架捕获http请求

laravel kernel 类 为laravel http 入口

middleware 类似于 过滤器 可以执行请求处理 然后next 执行处理链 必定有 handle 方法 当需要处理请求前操作 在调用 $next 前修改请求信息 当需要处理请求后 或者 在响应上操作 则 在$next后 修改信息 且返回结果必定为 $response对象

public function handle($request, Closure $next)
    {
        // Check if we're dealing with CORS and if we should handle it
        if (! $this->shouldRun($request)) {
            return $next($request);
        }

        // For Preflight, return the Preflight response
        if ($this->cors->isPreflightRequest($request)) {
            $response = $this->cors->handlePreflightRequest($request);

            $this->cors->varyHeader($response, 'Access-Control-Request-Method');

            return $response;
        }

        // Add the headers on the Request Handled event as fallback in case of exceptions
        if (class_exists(RequestHandled::class) && $this->container->bound('events')) {
            $this->container->make('events')->listen(RequestHandled::class, function (RequestHandled $event) {
                $this->addHeaders($event->request, $event->response);
            });
        }

        // Handle the request
        $response = $next($request);

        if ($request->getMethod() === 'OPTIONS') {
            $this->cors->varyHeader($response, 'Access-Control-Request-Method');
        }

        return $this->addHeaders($request, $response);
    }