Magento以编程方式申请优惠券但其印刷价值

I am using

Mage::getSingleton('checkout/cart')->getQuote()->getShippingAddress()
    ->setCollectShippingRates(true);
Mage::getSingleton('checkout/cart')->getQuote()
    ->setCouponCode($xfCouponCode)->collectTotals()->save();

i can apply coupon perfectly but when

Mage::getSingleton('checkout/cart')->getQuote()
    ->setCouponCode($xfCouponCode)->collectTotals()->save();

this line run then echo coupon in template. i don't know why echo coupon in template..

In the coupon.phtml in input field have show coupon just comment out $this->htmlEscape($this->getCouponCode()) like this:

<div class="input-box">
    <input class="input-text" id="coupon_code" name="coupon_code" value="<?php //echo $this->htmlEscape($this->getCouponCode()) ?>" />
</div>

Modify coupon code:

 $couponCode="amitG";
 $oldCouponCode = Mage::getSingleton('checkout/cart')->getQuote()->getCouponCode();
 if (strlen($couponCode) && strlen($oldCouponCode)) {
     Mage::getSingleton('checkout/cart')->getQuote()-->getShippingAddress()->setCollectShippingRates(true);
     Mage::getSingleton('checkout/cart')->getQuote()->setCouponCode(strlen($couponCode) ? $couponCode : '')
         ->collectTotals()
         ->save();
}