如何在zend_action中更改响应头

class MyController extends Zend_Controller_Action
{
    public function indexAction()
    {
        // 更改响应头
        $this->getResponse()
            ->setHeader('Content-Type', 'application/json')
            ->setHeader('Cache-Control', 'no-cache, must-revalidate')
            ->setHeader('Expires', '0');

        // 执行其他操作
        // ...
    }
}

class My_Controller_Plugin_ResponseHeader extends Zend_Controller_Plugin_Abstract
{
    public function preDispatch(Zend_Controller_Request_Abstract $request)
    {
        $response = $this->getResponse();
        $response->setHeader('Content-Type', 'application/json');
        $response->setHeader('Cache-Control', 'no-cache, must-revalidate');
        $response->setHeader('Expires', '0');
    }
}

$frontController = Zend_Controller_Front::getInstance();
$frontController->registerPlugin(new My_Controller_Plugin_ResponseHeader());