一种不显眼的过滤支付方式的方式是为名为 payment_method_is_active

的事件实现观察者步骤
1> 在 config.xml 中注册事件:‘payment_method_is_active’.在 app/code/local/MagePsycho/Paymentfilter/etc/config.xml 中添加以下 xml 代码:

An unobtrusive way of filtering payment method is to implement observer for event called payment_method_is_active

Steps
1> Register the event: ‘payment_method_is_active’ in config.xml. Add the following xml code in app/code/local/MagePsycho/Paymentfilter/etc/config.xml:

...
<global>
    ...
    <events>
        <payment_method_is_active>
            <observers>
                <paymentfilter_payment_method_is_active>
                    <type>singleton</type>
                    <class>paymentfilter/observer</class>
                    <method>paymentMethodIsActive</method>
                </paymentfilter_payment_method_is_active>
            </observers>
        </payment_method_is_active>
    </events>
    ...
</global>
...

2> 实现观察者模型创建观察者文件:app/code/local/MagePsycho/Paymentfilter/Model/Observer.php 并粘贴以下代码:

2> Implement the observer model Create observer file: app/code/local/MagePsycho/Paymentfilter/Model/Observer.php and paste the following code:

<?php
/**
 * @category   MagePsycho
 * @package    MagePsycho_Paymentfilter
 * @author     magepsycho@gmail.com
 * @website    http://www.magepsycho.com
 * @license    http://opensource.org/licenses/osl-3.0.php  Open Software License (OSL 3.0)
    */
class MagePsycho_Paymentfilter_Model_Observer {

    public function paymentMethodIsActive(Varien_Event_Observer $observer) {
        $event           = $observer->getEvent();
        $method          = $event->getMethodInstance();
        $result          = $event->getResult();
        $currencyCode    = Mage::app()->getStore()->getCurrentCurrencyCode();


            if($someTrueConditionGoesHere){
                $result->isAvailable = true;
            }else{
                $result->isAvailable = false;
            }

    }

}