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。
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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)
);
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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。
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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;
}
}
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步骤 3 : OrderItem
OrderItem在原来的基础上，增加一个Order属性
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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;
}
}
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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
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ResultSet rs = ps.getGeneratedKeys();
if (rs.next()) {
int id = rs.getInt(1);
o.setId(id);
}
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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();
}
}
}
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步骤 5 : OrderItemDAO
将OrderItem保存到数据库中
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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();
}
}
}
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步骤 6 : listOrderItem.jsp
在listOrderItem.jsp页面新增加一个"生成订单"的链接
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<c:if test="${!empty ois}">
<tr>
<td colspan="4" align="right">
<a href="/createOrder">生成订单</a>
</td>
</tr>
</c:if>
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<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8" import="java.util.*" isELIgnored="false"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<h1 align="center" >购物车</h1>
<table align='center' border='1' cellspacing='0'>
<tr>
<td>商品名称</td>
<td>单价</td>
<td>数量</td>
<td>小计</td>
</tr>
<c:forEach items="${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>
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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
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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");
}
}
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步骤 8 : 配置web.xml
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<?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>
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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
更多内容，点击了解： https://how2j.cn/k/cart/cart-order/599.html
