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移除书签33.3.7 创建购物车
到这里，我们了解了Amazon的所有查询功能，可以用它们来做些什么呢？很明显，我们可以使用这些功能来创建一个购物车。由于我们已经在第28章中详细介绍了它，因此在这里不再详细介绍。
购物车函数的代码如程序清单33-13所示。
程序清单33-13 cartfunctions.php——实现购物车
＜?php
require_once('AmazonResultSet.php');
//Using the function showSummary()in the file bookdisplay.php display
//the current contents of the shopping cart
function showCart($cart,$mode){
//build an array to pass
$products=array();
foreach($cart as$ASIN=＞$product){
$ars=getARS('asin',array('asin'=＞$ASIN,'mode'=＞$mode));
if($ars){
$products[]=$ars-＞getProduct(0);
}
}
//build the form to link to an Amazon.com shopping cart
echo"＜form method=\"POST\"
action=\"http://www.amazon.com/gp/aws/cart/add.html\"＞";
foreach($cart as$ASIN=＞$product){
$quantity=$cart[$ASIN]['quantity'];
echo"＜input type=\"hidden\"name=\"ASIN.".$ASIN."\"
value=\"".$ASIN."\"＞";
echo"＜input type=\"hidden\"name=\"Quantity.".$ASIN."\"
value=\"".$quantity."\"＞";
}
echo"＜input type=\"hidden\"name=\"SubscriptionId\"
value=\"".DEVTAG."\"＞
＜input type=\"hidden\"name=\"AssociateTag\"
value=\"".ASSOCIATEID."\"＞
＜input type=\"image\"src=\"images/checkout.gif\"
name=\"submit.add-to-cart\"value=\"Buy
From Amazon.com\"＞
When you have finished shopping press checkout to add all
the items in your Tahuayo cart to your Amazon cart and
complete your purchase.
＜/form＞
＜br/＞＜a href=\"index.php?action=emptycart\"＞＜img
src=\"images/emptycart.gif\"alt=\"Empty Cart\"
border=\"0\"＞＜/a＞
If you have finished with this cart,you can empty it
of all items.
＜/form＞
＜br/＞
＜h1＞Cart Contents＜/h1＞";
showSummary($products,1,count($products),$mode,0,true);
}
//show the small overview cart that is always on the screen
//only shows the last three items added
function showSmallCart(){
global$_SESSION;
echo"＜table border=\"1\"cellpadding=\"1\"cellspacing=\"0\"＞
＜tr＞＜td class=\"cartheading\"＞Your Cart$".
number_format(cartPrice(),2)."＜/td＞＜/tr＞
＜tr＞＜td class=\"cart\"＞".cartContents()."＜/td＞＜/tr＞";
//form to link to an Amazon.com shopping cart
echo"＜form method=\"POST\"
action=\"http://www.amazon.com/gp/aws/cart/add.html\"＞
＜tr＞＜td class=\"cartheading\"＞＜a
href=\"index.php?action=showcart\"＞＜img
src=\"images/details.gif\"border=\"0\"＞＜/a＞";
foreach($_SESSION['cart']as$ASIN=＞$product){
$quantity=$_SESSION['cart'][$ASIN]['quantity'];
echo"＜input type=\"hidden\"name=\"ASIN.".$ASIN."\"
value=\"".$ASIN."\"＞";
echo"＜input type=\"hidden\"name=\"Quantity.".$ASIN."\"
value=\"".$quantity."\"＞";
}
echo"＜input type=\"hidden\"name=\"SubscriptionId\"
value=\"".DEVTAG."\"＞
＜input type=\"hidden\"name=\"AssociateTag\"
value=\"".ASSOCIATEID."\"＞
＜input type=\"image\"src=\"images/checkout.gif\"
name=\"submit.add-to-cart\"value=\"Buy From
Amazon.com\"＞
＜/td＞＜/tr＞
＜/form＞
＜/table＞";
}
//show last three items added to cart
function cartContents(){
global$_SESSION;
$display=array_slice($_SESSION['cart'],-3,3);
//we want them in reverse chronological order
$display=array_reverse($display,true);
$result='';
$counter=0;
//abbreviate the names if they are long
foreach($display as$product){
if(strlen($product['name'])＜=40){
$result.=$product['name']."＜br/＞";
}else{
$result.=substr($product['name'],0,37)."…＜br/＞";
}
$counter++;
}
//add blank lines if the cart is nearly empty to keep the
//display the same
for(;$counter＜3;$counter++){
$result.="＜br/＞";
}
return$result;
}
//calculate total price of items in cart
function cartPrice(){
global$_SESSION;
$total=0.0;
foreach($_SESSION['cart']as$product){
$price=str_replace('$','',$product['price']);
$total+=$price*$product['quantity'];
}
return$total;
}
//add a single item to cart
//there is currently no facility to add more than one at a time
function addToCart(＆$cart,$ASIN,$mode){
if(isset($cart[$ASIN])){
$cart[$ASIN]['quantity']+=1;
}else{
//check that the ASIN is valid and look up the price
$ars=new AmazonResultSet;
$product=$ars-＞ASINSearch($ASIN,$mode);
if($product-＞valid()){
$cart[$ASIN]=array('price'=＞$product-＞ourPrice(),
'name'=＞$product-＞productName(),'quantity'=＞1);
}
}
}
//delete all of a particular item from cart
function deleteFromCart(＆$cart,$ASIN){
unset($cart[$ASIN]);
}
在这里，我们实现购物车的方法与前面稍微有些不同，例如addToCart()函数。当我们向购物车添加一个物品时，可以检查它是否具有一个有效的ASIN并且查找当前的价格（至少是缓存的价格）。
真正有趣的地方是这个问题：当客户付账时，如何让数据到达Amazon？
