不能声明类symfony 3

Question

我在实现MaintenanceListener服务时遇到了一个小错误，该服务将显示一个维护页面--这是我的services.yml

# https://symfony.com/doc/current/service_container.html
services:
    # default configuration for services in *this* file
    _defaults:
        # automatically injects dependencies in your services
        autowire: true
        # automatically registers your services as commands, event subscribers, etc.
        autoconfigure: true
        # this means you cannot fetch services directly from the container via $container->get()
        # if you need to do this, you can override this setting on individual services
        public: false

    # makes classes in Cocorico\CoreBundle\DataFixtures\ORM\ available to be used as services
    # this creates a service per class whose id is the fully-qualified class name

#    Cocorico\CoreBundle\DataFixtures\ORM\:
#        resource: '../../src/Cocorico/CoreBundle/DataFixtures/ORM/*'


    # makes classes in src/AppBundle available to be used as services
    # this creates a service per class whose id is the fully-qualified class name
    AppBundle\:
        resource: '../../src/AppBundle/*'
        # you can exclude directories or files
        # but if a service is unused, it's removed anyway
        exclude: '../../src/AppBundle/{Entity,Repository,Tests,Event}'

    # controllers are imported separately to make sure they're public
    # and have a tag that allows actions to type-hint services
#    AppBundle\Controller\:
#        resource: '../../src/AppBundle/Controller'
#        public: true
#        tags: ['controller.service_arguments']

    # add more services, or override services that need manual wiring
    # AppBundle\Service\ExampleService:
    #     arguments:
    #         $someArgument: 'some_value'
    maintenance_listener:
        class: AppBundle\Event\MaintenanceListener
        arguments:
        tags:
            - { name: kernel.event_listener, event: kernel.request, method: onKernelRequest }```

这是我的课：

<?php


namespace MListener;

use Symfony\Component\HttpKernel\Event\GetResponseEvent;
use Symfony\Component\HttpFoundation\Response;

class MListener
{
    public function onKernelRequest(GetResponseEvent $event)
    {
        $event->setResponse(new Response('Iziparty is in maintenance mode', Response::HTTP_SERVICE_UNAVAILABLE));
        $event->stopPropagation();
    }
}

下面是我得到的错误:在stderr中发送的/var/www/Symfony/src/AppBundle/Event/MaintenanceListener.php："PHP : PHP致命错误:不能声明类MListener\MListener，因为这个名称已经在第9行的/var/www/Symfony/src/AppBundle/Event/MaintenanceListener.php中使用了“，同时从上游读取响应头，谢谢帮助。

Answer 1

这一切都归结为自动魔法。autoload魔术假定了某种目录结构，即(除其他外)在composer.json中定义的目录结构。它实质上说：

命名空间AppBundle\...位于src/AppBundle/...目录中。

因此，每个类AppBundle\Something\Else都位于src/AppBundle/Something/Else.php中。

现在，symfony开始加载应该处理事件的服务(由于您的配置) AppBundle\Event\MaintenanceListener，它尝试实例化该服务，这导致自动加载程序加载仅包含类MListener/MListener的文件src/AppBundle/Event/MaintenanceListener.php。

由于自动加载有点麻烦，通常，它会尝试其他方法/定义，并可能尝试再次读取该文件，然后它将无法重新声明MListener/MListener类，因为它已经存在。

为了明确这一点:如果遵循标准(本例中是PSR-4 )，将目录结构绑定到命名空间结构，则这些方法非常有效。如果你把什么东西放进一个文件，根据PSR-4 -不属于那里，你会遇到问题，就像你得到的那个。

修复是简单而明显的:名称空间是目录(用反斜杠代替操作系统的任何目录分隔符)，文件名是类名(显然没有.php )。因此，要么将文件重命名为src/MListener/MListener.php，然后相应地调整services.yaml：MListener\Mlistener: ...，要么将文件中的名称空间和类分别重命名为AppBundle\Event和MaintenanceListener。

Answer 2

确保创建文件src/Event/MaintenanceListener.php

<?php

namespace AppBundle\Event;

use Symfony\Component\HttpKernel\Event\GetResponseEvent;
use Symfony\Component\HttpFoundation\Response;

class MaintenanceListener
{
    public function onKernelRequest(GetResponseEvent $event)
    {
        $event->setResponse(new Response('Iziparty is in maintenance mode', Response::HTTP_SERVICE_UNAVAILABLE));
        $event->stopPropagation();
    }
}

与文件service.yaml中声明的名称相同。