1.入口

laravel的请求处理入口在Illuminate\Foundation\Http\Kernel::handle方法里：

   public function handle($request)
    {
        try {
            $request->enableHttpMethodParameterOverride();
 
            $response = $this->sendRequestThroughRouter($request);
        } catch (Throwable $e) {
            $this->reportException($e);
 
            $response = $this->renderException($request, $e);
        }
 
        $this->app['events']->dispatch(
            new RequestHandled($request, $response)
        );
 
        return $response;
    }

2.启用请求方法覆盖

其实很简单，有些客户端无法发送PUT/PATCH等REST请求，所以使用参数来覆盖请求方法

在Symfony\Component\HttpFoundation\Request里

public function getMethod()
    {
        if (null !== $this->method) {
            return $this->method;
        }

        $this->m