用JSP和数据库实现购物车的源程序（1）

//shop_cart.jsp

<%@ page contentType="text/html;charset=gb2312"%>
<%@ page session="true" %>
<%@ page language="java" import="java.sql.*" %>
<jsp:useBean id="bka" scope="page" class="shop.bka" />
<%

String product_type;
String action;
int product_id;
int curpage;

//商品类型
if (request.getParameter("product_type")==null){
product_type="all";
}else{
product_type=request.getParameter("product_type");
}

//页数和商品类型参数，可以在“继续购物”时返回到上次购物的页面
if (request.getParameter("curpage")==null){
curpage=1;
}else{
curpage=java.lang.Integer.parseInt(request.getParameter
("curpage"));
}

//动作
if (request.getParameter("action")==null){
action="view";
}else{
action=request.getParameter("action");
}

//商品编号
if (request.getParameter("product_id")==null){
product_id=0;
}else{
product_id=java.lang.Integer.parseInt(request.getParameter
("product_id"));
}

int bbb;
bbb=1;

Integer num = new Integer(bbb);

//商店编号
session.putValue("shop_id",num);
//顾客username
session.putValue("guest_name","asp2001");

String guest_name=(String)session.getValue("guest_name");
Integer shop_id=(Integer)session.getValue("shop_id");

java.lang.String sql;
java.sql.ResultSet rs;

if (action.compareTo("add")==0) {

sql="select cart_quantity from shop_cart where cart_shop_id="
+ shop_id + " and cart_guest_id=" + guest_name + " and
cart_product_id="
+ product_id ;
rs = bka.executeQuery(sql);
if (rs.next()){
int cart_quantity;
cart_quantity=java.lang.Integer.parseInt(rs.getString
("cart_quantity"))+1;
sql="update shop_cart set cart_quantity=" + cart_quantity + " where cart_shop_id=" + shop_id + " and cart_guest_id=" +
guest_name + " and cart_product_id=" + product_id ;
rs = bka.executeQuery(sql);}
else
{
sql="insert into shop_cart (cart_shop_id,cart_guest_id,cart_product_id,cart_quantity) values
(" + shop_id + "," + guest_name + "," + product_id + ",1)";
rs = bka.executeQuery(sql);
}
}

if (action.compareTo("clear")==0) {
sql="delete from shop_cart where cart_shop_id=" + shop_id + " and cart_guest_id=" + guest_name + "";
rs = bka.executeQuery(sql);
}

if (action.compareTo("delete")==0) {
sql="delete from shop_cart where cart_shop_id=" + shop_id + " and cart_guest_id=" + guest_name + " and cart_product_id=" +
product_id ;
rs = bka.executeQuery(sql);
}
%>