购物车系列教材 （五）- 订单模块

在购物车页面，增加一个创建订单的超链 

通过创建订单，在Order表里新增一条数据，同时把session中的订单条目都保存到数据库中。

步骤1:SQL
步骤2:Order
步骤3:OrderItem
步骤4:OrderDAO
步骤5:OrderItemDAO
步骤6:listOrderItem.jsp
步骤7:OrderCreateServlet
步骤8:配置web.xml
步骤9:测试

步骤 1 : SQL

创建order表，里面有一个uid字段用于表明该订单属于哪个用户
注： order是关键字，不能直接用作表名，通常的做法是加一个下划线order_

创建orderitem,表里有id,pid,num,oid等字段。 分别表示主键，商品对应的id,购买数量以及订单id。

create table order_(

  id int AUTO_INCREMENT,

  uid int,

  primary key(id)

);

create table orderitem(

  id int AUTO_INCREMENT,

  pid int,

  num int,

  oid int,

  primary key(id)

);

步骤 2 : Order

与OrderItem类似的，会有一个User属性，而不是使用int类型的uid。

package bean;

public class Order {

    int id;

    User user;

    public int getId() {

        return id;

    }

    public void setId(int id) {

        this.id = id;

    }

    public User getUser() {

        return user;

    }

    public void setUser(User user) {

        this.user = user;

    }

}

步骤 3 : OrderItem

OrderItem在原来的基础上，增加一个Order属性

package bean;

public class OrderItem {

    private int id;

    private Product product;

    private int num;

    private Order order;

    public Order getOrder() {

        return order;

    }

    public void setOrder(Order order) {

        this.order = order;

    }

    public int getId() {

        return id;

    }

    public void setId(int id) {

        this.id = id;

    }

    public Product getProduct() {

        return product;

    }

    public void setProduct(Product product) {

        this.product = product;

    }

    public int getNum() {

        return num;

    }

    public void setNum(int num) {

        this.num = num;

    }

}

步骤 4 : OrderDAO

OrderDAO把订单对象保存到数据库中。

这里需要注意的是，Order对象保存到数据库中后，该对象就会有对应的id，这个id，在后续保存OrderItem的时候，是作为order id存在的。

所以在保存的数据库的时候，要获取自增长id
 

ResultSet rs = ps.getGeneratedKeys();

   if (rs.next()) {

   int id = rs.getInt(1);

   o.setId(id);

}

package dao;

import java.sql.Connection;

import java.sql.DriverManager;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

import java.sql.SQLException;

import bean.Order;

public class OrderDAO {

    public void insert(Order o) {

        try {

            Class.forName("com.mysql.jdbc.Driver");

            Connection c = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/cart?characterEncoding=UTF-8",

                    "root", "admin");

            String sql = "insert into order_ values(null,?)";

            PreparedStatement ps = c.prepareStatement(sql);

            ps.setInt(1, o.getUser().getId());

            ps.execute();

            ResultSet rs = ps.getGeneratedKeys();

            if (rs.next()) {

                int id = rs.getInt(1);

                o.setId(id);

            }

            ps.close();

            c.close();

        } catch (ClassNotFoundException e) {

            // TODO Auto-generated catch block

            e.printStackTrace();

        } catch (SQLException e) {

            // TODO Auto-generated catch block

            e.printStackTrace();

        }

    }

}

步骤 5 : OrderItemDAO

将OrderItem保存到数据库中

package dao;

import java.sql.Connection;

import java.sql.DriverManager;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

import java.sql.SQLException;

import java.util.ArrayList;

import java.util.List;

import bean.OrderItem;

import bean.Product;

public class OrderItemDAO {

    public static void main(String[] args) {

    }

     

    public void insert(OrderItem oi) {

        try {

            Class.forName("com.mysql.jdbc.Driver");

            Connection c = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/cart?characterEncoding=UTF-8",

                    "root", "admin");

            String sql = "insert into orderitem values(null,?,?,?)";

            PreparedStatement ps = c.prepareStatement(sql);

            ps.setInt(1,oi.getProduct().getId());

            ps.setInt(2,oi.getNum());

            ps.setInt(3,oi.getOrder().getId());

             

            ps.execute();

            ps.close();

            c.close();

        } catch (ClassNotFoundException e) {

            // TODO Auto-generated catch block

            e.printStackTrace();

        } catch (SQLException e) {

            // TODO Auto-generated catch block

            e.printStackTrace();

        }

         

    }

}

步骤 6 : listOrderItem.jsp

在listOrderItem.jsp页面新增加一个"生成订单"的链接
 

<c:if test="${!empty ois}">

        <tr>

            <td colspan="4" align="right">

                <a href="/createOrder">生成订单</a>

            </td>

        </tr>

</c:if>

<%@ page language="java" contentType="text/html; charset=UTF-8"

    pageEncoding="UTF-8" import="java.util.*" isELIgnored="false"%>

<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>

<h1 align="center" >购物车</h1>

<table align='center' border='1' cellspacing='0'>

    <tr>

        <td>商品名称</td>

        <td>单价</td>

        <td>数量</td>

        <td>小计</td>

    </tr>

    <c:forEach items="${ois}" var="oi" varStatus="st">

        <tr>

            <td>${oi.product.name}</td>

            <td>${oi.product.price}</td>

            <td>${oi.num}</td>

            <td>${oi.product.price*oi.num}</td>

        </tr>

    </c:forEach>

     

    <c:if test="${!empty ois}">

        <tr>

            <td colspan="4" align="right">

                <a href="createOrder">生成订单</a>

            </td>

        </tr>

    </c:if>

     

</table>

步骤 7 : OrderCreateServlet

OrderCreateServlet创建订单的Servlet
1. 首选判断用户是否登陆，如果没有登陆跳转到登陆页面
2. 创建一个订单对象，并设置其所属用户
3. 把该订单对象保存到数据库中
4. 遍历session中所有的订单项，设置他们的Order。 然后保存到数据库中
5. 清空session中的订单项
6. 最后打印订单创建成功

package servlet;

import java.io.IOException;

import java.util.List;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import bean.Order;

import bean.OrderItem;

import bean.User;

import dao.OrderDAO;

import dao.OrderItemDAO;

public class OrderCreateServlet extends HttpServlet {

    protected void service(HttpServletRequest request, HttpServletResponse response)

            throws ServletException, IOException {

        User u = (User) request.getSession().getAttribute("user");

        if(null==u){

            response.sendRedirect("/login.jsp");

            return;

        }

         

        Order o = new Order();

        o.setUser(u);

        new OrderDAO().insert(o);

        List<OrderItem> ois = (List<OrderItem>) request.getSession().getAttribute("ois");

        for (OrderItem oi : ois) {

            oi.setOrder(o);

            new OrderItemDAO().insert(oi);

        }

         

        ois.clear();

         

        response.setContentType("text/html; charset=UTF-8");

        response.getWriter().println("订单创建成功");

    }

}

步骤 8 : 配置web.xml

<?xml version="1.0" encoding="UTF-8"?>

<web-app>

    <servlet>

        <servlet-name>ProductListServlet</servlet-name>

        <servlet-class>servlet.ProductListServlet</servlet-class>

    </servlet>

    <servlet-mapping>

        <servlet-name>ProductListServlet</servlet-name>

        <url-pattern>/listProduct</url-pattern>

    </servlet-mapping>

    <servlet>

        <servlet-name>UserLoginServlet</servlet-name>

        <servlet-class>servlet.UserLoginServlet</servlet-class>

    </servlet>

    <servlet-mapping>

        <servlet-name>UserLoginServlet</servlet-name>

        <url-pattern>/login</url-pattern>

    </servlet-mapping>

    <servlet>

        <servlet-name>OrderItemAddServlet</servlet-name>

        <servlet-class>servlet.OrderItemAddServlet</servlet-class>

    </servlet>

    <servlet-mapping>

        <servlet-name>OrderItemAddServlet</servlet-name>

        <url-pattern>/addOrderItem</url-pattern>

    </servlet-mapping>

     

    <servlet>

        <servlet-name>OrderItemListServlet</servlet-name>

        <servlet-class>servlet.OrderItemListServlet</servlet-class>

    </servlet>

    <servlet-mapping>

        <servlet-name>OrderItemListServlet</servlet-name>

        <url-pattern>/listOrderItem</url-pattern>

    </servlet-mapping>

    <servlet>

        <servlet-name>OrderCreateServlet</servlet-name>

        <servlet-class>servlet.OrderCreateServlet</servlet-class>

    </servlet>

    <servlet-mapping>

        <servlet-name>OrderCreateServlet</servlet-name>

        <url-pattern>/createOrder</url-pattern>

    </servlet-mapping>

</web-app>

步骤 9 : 测试

点击创建订单后，在数据库中的orderitem表观察到插入的数据

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