Php Symfony 2.5-我无法捕获异常

我正在基于symfony 2.5构建一个新项目的最后阶段，我认为拥有自定义错误页面会很好。我创建了自己的异常侦听器，请参见下面的代码：

这是服务声明：

kernel.listener.core_exception_listener:
    class: MyCompany\CoreBundle\Listener\ExceptionListener
    arguments: [@templating, @kernel]
    tags:
        - { name: kernel.event_listener, event: kernel.exception, method: onKernelException }

<?php
namespace MyCompany\CoreBundle\Listener;

use Symfony\Component\HttpKernel\Event\GetResponseForExceptionEvent;
use Symfony\Component\HttpFoundation\Response;
use Symfony\Component\HttpKernel\Exception\HttpExceptionInterface;

use Symfony\Bundle\FrameworkBundle\Templating\EngineInterface;

use Symfony\Component\HttpKernel\Exception\NotFoundHttpException;

class ExceptionListener
{
    protected $templating;
    protected $kernel;

    public function __construct(EngineInterface $templating, $kernel)
    {
        $this->templating = $templating;
        $this->kernel = $kernel;
    }

    public function onKernelException(GetResponseForExceptionEvent $event)
    {
        // provide the better way to display a enhanced error page only in prod environment, if you want
        if ('prod' == $this->kernel->getEnvironment()) {
            // exception object
            $exception = $event->getException();

            // new Response object
            $response = new Response();

            if($exception instanceof NotFoundHttpException) {
                $template = 'CoreBundle:Exception:404.html.php';
            } else {
                $template = 'CoreBundle:Exception:exception.html.php';
            }

            $response->setContent(
                // create you custom template AcmeFooBundle:Exception:exception.html.twig
                $this->templating->render(
                    $template,
                    array('exception' => $exception)
                )
            );


            // HttpExceptionInterface is a special type of exception
            // that holds status code and header details
            if ($exception instanceof HttpExceptionInterface) {
                $response->setStatusCode($exception->getStatusCode());
                $response->headers->replace($exception->getHeaders());
            } else {
                $response->setStatusCode(500);
            }

            // set the new $response object to the $event
            $event->setResponse($response);
        }
    }
}

下面是实际的PHP类：

kernel.listener.core_exception_listener:
    class: MyCompany\CoreBundle\Listener\ExceptionListener
    arguments: [@templating, @kernel]
    tags:
        - { name: kernel.event_listener, event: kernel.exception, method: onKernelException }

<?php
namespace MyCompany\CoreBundle\Listener;

use Symfony\Component\HttpKernel\Event\GetResponseForExceptionEvent;
use Symfony\Component\HttpFoundation\Response;
use Symfony\Component\HttpKernel\Exception\HttpExceptionInterface;

use Symfony\Bundle\FrameworkBundle\Templating\EngineInterface;

use Symfony\Component\HttpKernel\Exception\NotFoundHttpException;

class ExceptionListener
{
    protected $templating;
    protected $kernel;

    public function __construct(EngineInterface $templating, $kernel)
    {
        $this->templating = $templating;
        $this->kernel = $kernel;
    }

    public function onKernelException(GetResponseForExceptionEvent $event)
    {
        // provide the better way to display a enhanced error page only in prod environment, if you want
        if ('prod' == $this->kernel->getEnvironment()) {
            // exception object
            $exception = $event->getException();

            // new Response object
            $response = new Response();

            if($exception instanceof NotFoundHttpException) {
                $template = 'CoreBundle:Exception:404.html.php';
            } else {
                $template = 'CoreBundle:Exception:exception.html.php';
            }

            $response->setContent(
                // create you custom template AcmeFooBundle:Exception:exception.html.twig
                $this->templating->render(
                    $template,
                    array('exception' => $exception)
                )
            );


            // HttpExceptionInterface is a special type of exception
            // that holds status code and header details
            if ($exception instanceof HttpExceptionInterface) {
                $response->setStatusCode($exception->getStatusCode());
                $response->headers->replace($exception->getHeaders());
            } else {
                $response->setStatusCode(500);
            }

            // set the new $response object to the $event
            $event->setResponse($response);
        }
    }
}

---

要捕获
pdo异常
，必须对其命名。

将其添加为use语句或在调用时添加前导\。
比如,

try {
   // your code
} catch (\PDOException $pdo_ex) {
   die("Oops, ".$pdo_ex->getMessage());
}

这是帮助我处理预期错误的代码

}
运行时，条令会引发异常-我的测试包括mysql服务器不可用的场景。我无法插入try-catch代码块，因为这意味着我必须更改代码核心。