购物车为空!

数据库操作部分

程序用到两个表：
1 shop_cart表
cart_id int 购物车编号 自动编号
cart_shop_id nvarchar 商店编号
cart_product_id nvarchar 商品编号
cart_quantity int 商品数量
临时存放购物车数据

2 shop_product表
product_id int 商品编号 自动编号
shop_id nvarchar 商店编号
product_name nvarchar 商品名称
product_bb nvarchar 商品介绍
product_price int 市场价
product_discount int 优惠价
product_img img 图片
product_status nvarchar 状态
product_first int 定金比例
product_type nvanchar 商品类型
存放商品资料

使用bka.java制成的javabean：bka.class可以提供对数据库的操作。
另外，需在控制面板的系统DSN中注册bka.dsn，
从而可使JSP通过JDBC-ODBC来调用sql数据库。
在页面中调用javabean，基本上可采用以下方式：

<%@ page language="java" import="java.sql.*" %>

<%
String sql="select * from xxx";
ResultSet rs = RegisterBean.executeQuery(sql);
if(rs.next()) {
rs.close();
RegisterBean.closeStmt();
session.putValue("register_message","duplicate name found!");
}
%>
注意应在使用后将rs关闭。
以下是bka.java的源程序。注意在使用前需用javac加以编译成为class文件即javabean.
--shop/bka.java--
package shop;
import java.sql.*;

public class bka {
String sDBDriver = "sun.jdbc.odbc.JdbcOdbcDriver";
String sConnStr = "jdbc:odbc:bka";
Connection conn = null;
ResultSet rs = null;

public bka() {
try {
Class.forName(sDBDriver);
}
catch(java.lang.ClassNotFoundException e) {
System.err.println("bka(): " + e.getMessage());
}
}
public ResultSet executeQuery(String sql) {
rs = null;
try {
conn = DriverManager.getConnection(sConnStr,"xxx","yyy");
Statement stmt = conn.createStatement();
rs = stmt.executeQuery(sql);
}
catch(SQLException ex) {
System.err.println("aq.executeQuery: " + ex.getMessage());
}
return rs;
}
} 1、重新计费部分还没有做好，大家自己动手吧！
2、下一版本将用session做。
//shop_cart.jsp
<%@ page contentType="text/html;charset=gb2312"%>
<%@ page session="true" %>
<%@ page language="java" import="java.sql.*" %>

<%
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);
}
%>