[Zend Framework] Zend_Controller: ContextSwitch アクションヘルパーを利用して、ひとつのコントローラー/アクションでhtml, xml, json, csv出力に対応する

public function init() {
    $contextSwitch = $this->_helper->getHelper('contextSwitch');
    $contextSwitch->addActionContext('cs', 'xml');
    $contextSwitch->addActionContext('cs', 'json');
    $filename = time() . '.csv';
    $contextSwitch->addContext('csv',
        array('suffix' => 'csv',
              'headers' => array('Content-Type' => 'application/csv',
                                 'Content-Disposition' => 'attachment; filename="'.$filename.'"',
                                 'Pragma' => 'public',
                                 'Expires' => '0',
                                 'Cache-control' => 'public')
                               ));
    $contextSwitch->addActionContext('cs', 'csv');
    $contextSwitch->initContext();
}

public function csAction() {
    $results = array(
        array('title' => '路傍の石', 'author' => '山本有三', 'pub' => '1937'),
        array('title' => '羅生門', 'author' => '芥川龍之介', 'pub' => '1915'),
        array('title' => '城の崎にて', 'author' => '志賀直哉', 'pub' => '1917')
    );
    $this->view->assign('results',$results);
}

<? foreach($this->results as $row): ?>
<?=$this->escape($row['title']) ?> : <?=$this->escape($row['author']) ?> （<?=$this->escape($row['pub']) ?>）
<? endforeach; ?>

<?php
foreach($this->results as $row) {
    $data = $this->escape($row['title']) . ','
           .$this->escape($row['author']) . ','
           .$this->escape($row['pub']) . PHP_EOL;
    echo mb_convert_encoding($data, "SJIS", "UTF-8");
}