来自控制器的控制台/Symfony 调用命令

当我尝试从控制器调用命令时，控制台遇到了一些问题。我在Symfony Cookbook中找到了一种方法：http://symfony.com/doc/current/cookbook/console/command_in_controller.html

好像行不通...也许我忘记了什么！

命令：

namespace AppBundle'Command;
use Symfony'Component'Console'Command'Command;
use Symfony'Component'Console'Input'InputArgument;
use Symfony'Component'Console'Input'InputInterface;
use Symfony'Component'Console'Input'InputOption;
use Symfony'Component'Console'Output'OutputInterface;
class GreetCommand extends Command
{
    protected function configure()
    {
        $this
            ->setName('demo:greet')
            ->setDescription('Greet someone')
            ->addArgument(
                'name',
                InputArgument::OPTIONAL,
                'Who do you want to greet?'
            )
            ->addOption(
                'yell',
                null,
                InputOption::VALUE_NONE,
                'If set, the task will yell in uppercase letters'
            )
        ;
    }
    protected function execute(InputInterface $input, OutputInterface $output)
    {
        $name = $input->getArgument('name');
        if ($name) {
            $text = 'Hello '.$name;
        } else {
            $text = 'Hello';
        }
        if ($input->getOption('yell')) {
            $text = strtoupper($text);
        }
        $output->writeln($text);
    }
}

（该命令在cmd中运行良好）

控制器：

namespace AppBundle'Controller;
use Symfony'Bundle'FrameworkBundle'Controller'Controller;
use Symfony'Component'Console'Application;
use Symfony'Component'Console'Input'ArrayInput;
use Symfony'Component'Console'Output'BufferedOutput;

class MainController extends Controller
{
    public function indexAction()
    {
        $kernel = $this->get('kernel');
        $application = new Application($kernel);
        $application->setAutoExit(false);
        $input = new ArrayInput(array(
            'command' => 'demo:greet'
        ));
        $output = new BufferedOutput();
        $application->run($input, $output);
        $content = $output->fetch();
        dump($content);die;
    }
}

响应

[Symfony'Component'Console'Exception'CommandNotFoundException] There are no commands defined in the "demo" namespace. 

提前感谢您的帮助。