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题目：基于数据库的商品购物系统Java实现

内容/作用：知识点/设计/实验/作业/练习

学习：Java和数据库的综合应用

一、前言

   基于数据库，用Java实现对模拟一个商品购物系统的增加、删除、查找、修改功能。

数据库表

Java包

实现后界面

二、环境与设备

1.软件：IntelliJ IDEA 2022.3.2
2.环境：Windows 11 and JDK 11

三、数据库部分

1、数据库建表

上面已经说了，需要建3个表。首先先先建一个数据库：shopdb。在其数据库中创建表，顾客表customer，管理员表sys_manager，商品表goods。

顾客表customer

create table customer(
id int not null primary key auto_increment,
phone varchar(20) not null,
password varchar(20) not null,
balance double default '0',
name varchar(20) ,
address text
)

管理员表sys_manager

create table sys_manager(
id int not null primary key auto_increment,
username varchar(20) not null,
password varchar(20) not null
)

商品表goods

create table goods(
id int not null primary key auto_increment,
brand varchar(20) not null,
name varchar(20) not null,
price double not null,
num int not null,
make_date date not null
)

表中添加数据

随便添加几行，为了方便测试，例如：

顾客表

管理员表

商品表

好的到这里，数据库部分就完成编写。下面就是Java编写代码！！
好的到这里，数据库部分就完成编写。下面就是Java编写代码！！
好的到这里，数据库部分就完成编写。下面就是Java编写代码！！
(！！三遍！！？？)

四、Java部分

   首先：
我们先创建一个包shopsys，包中，再创建4个包，分别为：dao,entity,service,util。

作用分别如下：

dao：

 * DAO层  数据访问层，用于访问数据库的一个类
 * 命名通常为表名+DAO
 * 在其中定义某张表的CURD操作

entity：

* entity 实体层，对应某张表，属性就是表的字段
* 类名与表名一致
* 标准的实体类也称为JavaBean，是组成Java程序的最小的类
* JavaBean需要满足：
* 1.这个类必须是公共的
* 2.提供无参数的构造方法
* 3.对属性进行封装

service：

 * 业务层，调用数据访问层的方法

util：

 * 定义数据库工具类，简化JDBC操作
 * 可以简化的操作
 * 1.加载驱动   
 * 2.连接数据库 
 * 6.关闭   

创建下图文件，重命名如下：

开始编写代码：
开始编写代码：
开始编写代码：
模板已经建好了，代码我就直接放上了。
每个java文件导包是否正确！！！
每个java文件导包是否正确！！！
每个java文件导包是否正确！！！

CustomerDao

public class CustomerDao {
    private Connection conn;
    private PreparedStatement pst;
    private ResultSet rs;


    public Customer login(String phone, String password) {
        conn = DBUtil.getConn();
        String sql = "select * from customer where phone=? and password=?";
        try {
            pst = conn.prepareStatement(sql);
            pst.setString(1, phone);
            pst.setString(2, password);
            rs = pst.executeQuery();
            if (rs.next()) {
                int id = rs.getInt(1);
                double balance = rs.getDouble(4);
                String name = rs.getString(5);
                String address = rs.getString(6);
                return new Customer(id, phone, password, balance, name, address);
            }
        } catch (SQLException e) {
            System.out.println("顾客登录异常" + e);
        } finally {
            DBUtil.release(conn, pst, rs);
        }
        return null;
    }

    public boolean register(String phone, String password) {
        conn = DBUtil.getConn();
        try {
            //判断用户是否存在
            String sql = "select * from customer where phone=? ";
            pst = conn.prepareStatement(sql);
            pst.setString(1, phone);
            rs = pst.executeQuery();
            if (rs.next()) {
                return false;
            }
            //真实注册
            String sql2 = "insert into customer(phone,password) values(?,?)";
            pst = conn.prepareStatement(sql2);
            pst.setString(1, phone);
            pst.setString(2, password);
            return pst.executeUpdate() > 0;
        } catch (SQLException e) {
            System.out.println("注册异常" + e);
        } finally {
            DBUtil.release(conn, pst, rs);
        }
        return false;
    }

    public boolean updateInfo(String name, String address, int id) {
        conn = DBUtil.getConn();
        try {
            String sql = "update customer set name=?,address=? where id=?";
            pst = conn.prepareStatement(sql);
            pst.setString(1, name);
            pst.setString(2, address);
            pst.setInt(3, id);
            return pst.executeUpdate() > 0;
        } catch (SQLException e) {
            System.out.println("修改信息异常" + e);
        } finally {
            DBUtil.release(conn, pst, rs);
        }
        return false;
    }

    public boolean changeBalance(double balance, int id) {
        conn = DBUtil.getConn();
        try {
            String sql = "update customer set balance=? where id=?";
            pst = conn.prepareStatement(sql);
            pst.setDouble(1, balance);
            pst.setInt(2, id);
            return pst.executeUpdate() > 0;
        } catch (SQLException e) {
            System.out.println("修改金额信息异常" + e);
        } finally {
            DBUtil.release(conn, pst, rs);
        }
        return false;
    }
}

GoodsDao

public class GoodsDao {
    private Connection conn;
    private PreparedStatement pst;
    private ResultSet rs;


    public List<Goods> queryAll() {
        ArrayList<Goods> list = new ArrayList<>();
        conn = DBUtil.getConn();
        String sql = "select * from goods";
        try {
            pst = conn.prepareStatement(sql);
            rs = pst.executeQuery();
            while (rs.next()) {
                int id = rs.getInt(1);
                String brand = rs.getString(2);
                String name = rs.getString(3);
                double price = rs.getDouble(4);
                int num = rs.getInt(5);
                String makeDate = rs.getString(6);
                Goods goods = new Goods(id, brand, name, price, num, makeDate);
                list.add(goods);
            }
        } catch (SQLException e) {
            System.out.println("查询所有商品异常" + e);
        } finally {
            DBUtil.release(conn, pst, rs);
        }
        return list;
    }

    public Goods queryById(int id) {
        conn = DBUtil.getConn();
        String sql = "select * from goods where id=?";
        try {
            pst = conn.prepareStatement(sql);
            pst.setInt(1, id);
            rs = pst.executeQuery();
            while (rs.next()) {
                String brand = rs.getString(2);
                String name = rs.getString(3);
                double price = rs.getDouble(4);
                int num = rs.getInt(5);
                String makeDate = rs.getString(6);
                return new Goods(id, brand, name, price, num, makeDate);
            }
        } catch (SQLException e) {
            System.out.println("根据id查询商品异常" + e);
        } finally {
            DBUtil.release(conn, pst, rs);
        }
        return null;
    }

    public boolean insert(Goods goods) {
        conn = DBUtil.getConn();
        try {
            String sql = "insert into goods values(null,?,?,?,?,?)";
            pst = conn.prepareStatement(sql);
            pst.setString(1,goods.getBrand());
            pst.setString(2,goods.getName());
            pst.setDouble(3, goods.getPrice());
            pst.setInt(4, goods.getNum());
            pst.setString(5,goods.getMakeDate().toString());
            return pst.executeUpdate() > 0;
        } catch (SQLException e) {
            System.out.println("修改商品信息异常" + e);
        } finally {
            DBUtil.release(conn, pst, rs);
        }
        return false;
    }

    public boolean updateGoods(double price, int num, int id) {
        conn = DBUtil.getConn();
        try {
            String sql = "update goods set price=?,num=? where id=?";
            pst = conn.prepareStatement(sql);
            pst.setDouble(1, price);
            pst.setInt(2, num);
            pst.setInt(3, id);
            return pst.executeUpdate() > 0;
        } catch (SQLException e) {
            System.out.println("修改商品信息异常" + e);
        } finally {
            DBUtil.release(conn, pst, rs);
        }
        return false;
    }

    public boolean deleteById(int id) {
        conn = DBUtil.getConn();
        try {
            String sql = "delete from goods  where id=?";
            pst = conn.prepareStatement(sql);
            pst.setInt(1, id);
            return pst.executeUpdate() > 0;
        } catch (SQLException e) {
            System.out.println("删除商品异常" + e);
        } finally {
            DBUtil.release(conn, pst, rs);
        }
        return false;
    }

}

SysManagerDao

public class SysManagerDao {
    private Connection conn;
    private PreparedStatement pst;
    private ResultSet rs;


    public SysManager login(String username, String password) {
        conn = DBUtil.getConn();
        String sql = "select * from sys_manager where username=? and password=?";
        try {
            pst = conn.prepareStatement(sql);
            pst.setString(1, username);
            pst.setString(2, password);
            rs = pst.executeQuery();
            if (rs.next()) {
                return new SysManager(rs.getInt(1), username, password);
            }
        } catch (SQLException e) {
            System.out.println("管理员登录异常" + e);
        } finally {
            DBUtil.release(conn, pst, rs);
        }
        return null;
    }
}

Customer

public class Customer {
    private int id;
    private String phone;
    private String password;
    private double balance;
    private String name;
    private String address;

   @Override
    public String toString() {
        return "Customer{" +
                "id=" + id +
                ", phone='" + phone + '\'' +
                ", password='" + password + '\'' +
                ", balance=" + balance +
                ", name='" + name + '\'' +
                ", address='" + address + '\'' +
                '}';
    }

    public Customer(String phone, String password) {
        this.phone = phone;
        this.password = password;
    }

    public Customer() {
    }

    public Customer(String phone, String password, double balance, String name, String address) {
        this.phone = phone;
        this.password = password;
        this.balance = balance;
        this.name = name;
        this.address = address;
    }

    public Customer(int id, String phone, String password, double balance, String name, String address) {
        this.id = id;
        this.phone = phone;
        this.password = password;
        this.balance = balance;
        this.name = name;
        this.address = address;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getPhone() {
        return phone;
    }

    public void setPhone(String phone) {
        this.phone = phone;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public double getBalance() {
        return balance;
    }

    public void setBalance(double balance) {
        this.balance = balance;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }
}

Goods

public class Goods {
    private int id;
    private String brand;
    private String name;
    private double price;
    private int num;
    private String makeDate;

    @Override
    public String toString() {
        return "Goods{" +
                "id=" + id +
                ", brand='" + brand + '\'' +
                ", name='" + name + '\'' +
                ", price=" + price +
                ", num=" + num +
                ", makeDate=" + makeDate +
                '}';
    }

    public Goods() {
    }

    public Goods(String brand, String name, double price, int num, String makeDate) {
        this.brand = brand;
        this.name = name;
        this.price = price;
        this.num = num;
        this.makeDate = makeDate;
    }

    public Goods(int id, String brand, String name, double price, int num, String makeDate) {
        this.id = id;
        this.brand = brand;
        this.name = name;
        this.price = price;
        this.num = num;
        this.makeDate = makeDate;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getBrand() {
        return brand;
    }

    public void setBrand(String brand) {
        this.brand = brand;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public double getPrice() {
        return price;
    }

    public void setPrice(double price) {
        this.price = price;
    }

    public int getNum() {
        return num;
    }

    public void setNum(int num) {
        this.num = num;
    }

    public String getMakeDate() {
        return makeDate;
    }

    public void setMakeDate(String makeDate) {
        this.makeDate = makeDate;
    }
}

SysManager

public class SysManager {
    private int id;
    private String username;
    private String password;

    @Override
    public String toString() {
        return "SysManager{" +
                "id=" + id +
                ", username='" + username + '\'' +
                ", password='" + password + '\'' +
                '}';
    }

    public SysManager() {
    }

    public SysManager(String username, String password) {
        this.username = username;
        this.password = password;
    }

    public SysManager(int id, String username, String password) {
        this.id = id;
        this.username = username;
        this.password = password;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }
}

Main

public class Main {
    CustomerDao customerDao = new CustomerDao();
    GoodsDao goodsDao = new GoodsDao();
    SysManagerDao sysManagerDao = new SysManagerDao();
    Scanner sc = new Scanner(System.in);

    public static void main(String[] args) {

        new Main().menu();
    }


    public void cusMenu(Customer customer) {
        System.out.println("1.查看个人信息");
        System.out.println("2.修改个人信息");
        System.out.println("3.充值");
        System.out.println("4.购买");
        System.out.println("5.返回");
        switch (sc.nextInt()) {
            case 1:
                System.out.println(customer);
                break;
            case 2:
                System.out.println("请输入用户名");
                String newName = sc.next();
                System.out.println("请输入地址");
                String newAddress = sc.next();
                if (customerDao.updateInfo(newName, newAddress, customer.getId())) {
                    //既改动数据库，又改动当前方法的参数
                    customer.setName(newName);
                    customer.setAddress(newAddress);
                    System.out.println("修改成功");
                }
                break;
            case 3:
                System.out.println("请输入充值金额");
                double money = sc.nextDouble();
                double newBalance = customer.getBalance() + money;
                customer.setBalance(newBalance);
                if (customerDao.changeBalance(newBalance, customer.getId())) {
                    System.out.println("充值成功");
                }
                break;
            case 4:
                //所有商品
                goodsDao.queryAll().forEach(System.out::println);
                System.out.println("请输入要购买的商品编号");
                Goods goods = goodsDao.queryById(sc.nextInt());
                System.out.println("请输入要购买的数量");
                int buyNum = sc.nextInt();
                //判断库存和余额
                if (goods.getNum() < buyNum) {
                    System.out.println("库存不足");
                    return;
                }
                if (buyNum * goods.getPrice() > customer.getBalance()) {
                    System.out.println("余额不足");
                    return;
                }
                //同时执行两张表的修改
                boolean b = goodsDao.updateGoods(goods.getPrice(), goods.getNum() - buyNum, goods.getId());
                boolean b1 = customerDao.changeBalance(customer.getBalance() - buyNum * goods.getPrice(), customer.getId());
                //更新方法变量的值
                customer.setBalance(customer.getBalance() - buyNum * goods.getPrice());
                if (b && b1) {
                    System.out.println("===============");
                    System.out.println("商品：" + goods.getBrand() + "\t" + goods.getName());
                    System.out.println("单价：" + goods.getPrice());
                    System.out.println("购买数量：" + buyNum);
                    System.out.println("总价：" + buyNum * goods.getPrice());
                    System.out.println("收货人：" + customer.getName());
                    System.out.println("收货人电话：" + customer.getPhone());
                    System.out.println("收货地址：" + customer.getAddress());
                    System.out.println("===============");
                }
                break;
            case 5:
                menu();
                break;
        }
        cusMenu(customer);
    }


    public void sysMenu() {
        System.out.println("1.查看所有商品");
        System.out.println("2.添加商品");
        System.out.println("3.修改商品");
        System.out.println("4.删除商品");
        System.out.println("5.返回");
        switch (sc.nextInt()) {
            case 1:
                goodsDao.queryAll().forEach(System.out::println);
                break;
            case 2:
                Goods g1 = new Goods("娃哈哈", "纯净水", 2, 50, new Date().toString());
                Goods g4 = new Goods("农夫山泉", "纯净水", 2, 50, new Date().toString());
                Goods g3 = new Goods("康师傅", "冰红茶", 3, 50, new Date().toString());
                Goods g2 = new Goods("康师傅", "红烧牛肉面", 4.5, 50, new Date().toString());
                goodsDao.insert(g1);
                goodsDao.insert(g2);
                goodsDao.insert(g3);
                goodsDao.insert(g4);
                break;
            case 3:
                System.out.println("请输入商品编号");
                int id = sc.nextInt();
                System.out.println("请输入新价格");
                double newPrice = sc.nextDouble();
                System.out.println("请输入新库存");
                int newNum = sc.nextInt();
                if (goodsDao.updateGoods(newPrice, newNum, id)) {
                    System.out.println("修改成功");
                }
                break;
            case 4:
                System.out.println("请输入商品编号");
                int delId = sc.nextInt();
                if (goodsDao.deleteById(delId)) {
                    System.out.println("删除成功");
                }
                break;
        }
        sysMenu();
    }

    public void menu() {
        System.out.println("1.管理员登录");
        System.out.println("2.顾客登录");
        System.out.println("3.注册顾客");
        switch (sc.nextInt()) {
            case 1:
                System.out.println("请输入用户名");
                String username = sc.next();
                System.out.println("请输入密码");
                String password = sc.next();
                SysManager sysManager = sysManagerDao.login(username, password);
                if (sysManager != null) {
                    //管理员界面
                    sysMenu();
                } else {
                    System.out.println("用户名或密码错误");
                }
                break;
            case 2:
                System.out.println("请输入电话");
                String phone = sc.next();
                System.out.println("请输入密码");
                String pwd = sc.next();
                Customer customer = customerDao.login(phone, pwd);
                if (customer != null) {
                    cusMenu(customer);
                } else {
                    System.out.println("用户名或密码错误");
                }
                break;
            case 3:
                System.out.println("请输入电话");
                String regPhone = sc.next();
                System.out.println("请输入密码");
                String regPwd = sc.next();
                if (customerDao.register(regPhone, regPwd)) {
                    System.out.println("顾客界面");
                } else {
                    System.out.println("该用户已注册");
                }
                break;
        }
        menu();
    }
}

DBUtil

public class DBUtil {
    /*
     * 定义静态代码块用于加载驱动
     * */
    static {
        try {
            Class.forName("com.mysql.cj.jdbc.Driver");
        } catch (ClassNotFoundException e) {
            System.out.println("驱动不存在" + e);
        }
    }

    //定义静态常量保存连接数据库的字符串
    private final static String URL = "jdbc:mysql://localhost:3306/shopdb?serverTimezone=Asia/Shanghai";
    private final static String USERNAME = "root";
    private final static String PASSWORD = "root";

    /*
     * 定义静态方法获取连接对象
     * */
    public static Connection getConn() {
        Connection connection = null;
        try {
            connection = DriverManager.getConnection(URL, USERNAME, PASSWORD);
        } catch (SQLException e) {
            System.out.println("连接数据库信息异常" + e);
        }
        return connection;
    }

    /*
     * 定义静态方法释放资源
     * */
    public static void release(Connection conn, PreparedStatement pst, ResultSet rs) {
        //使用了哪个接口就关闭那个接口
        try {
            if (rs != null) {
                rs.close();
            }
            if (pst != null) {
                pst.close();
            }
            if (conn != null) {
                conn.close();
            }
        } catch (SQLException e) {
            System.out.println("关闭异常" + e);
        }
    }


}

DBUtil中有一个地方需要改动！！！
DBUtil中有一个地方需要改动！！！
DBUtil中有一个地方需要改动！！！

端口号，修改为自己的电脑端口就行，默认是3306.
数据库名称，就是创建数据库的名字，前面也收过了。

上面的名字和密码，改为自己安装数据库时设置的账户和密码就行。
改完之后，导包正确，就能运行。
代码就不详细讲解，通俗易懂，都加以注释。

五、总结与分析

   到这里，虽然有些地方不足，但学完数据库知识，能和Java综合，已经很不错了。宝子们，咋们下期见。。