用java编写一个简单的使用数据库储存信息的食堂管理系统

好的，下面是一个使用Java语言和MySQL数据库的简单食堂管理系统的示例代码：

1. 首先需要创建MySQL数据库和相应的数据表，例如创建一个名为canteen的数据库，其中有一个名为dishes的数据表，包含字段id、name、price和inventory，用于存储菜品的信息。可以使用以下SQL语句创建该数据表：

CREATE DATABASE canteen;

USE canteen;

CREATE TABLE dishes (
    id INT PRIMARY KEY AUTO_INCREMENT,
    name VARCHAR(50) NOT NULL,
    price DECIMAL(8,2) NOT NULL,
    inventory INT NOT NULL
);

2. 在Java程序中使用JDBC连接MySQL数据库，并实现菜品信息的增删改查功能。可以使用以下代码作为示例：

import java.sql.*;

public class CanteenManagementSystem {
    // 数据库连接信息
    private static final String JDBC_URL = "jdbc:mysql://localhost:3306/canteen?useSSL=false&serverTimezone=UTC";
    private static final String JDBC_USERNAME = "root";
    private static final String JDBC_PASSWORD = "password";

    // 菜品信息增删改查的SQL语句
    private static final String INSERT_DISH = "INSERT INTO dishes(name, price, inventory) VALUES (?, ?, ?)";
    private static final String DELETE_DISH = "DELETE FROM dishes WHERE id = ?";
    private static final String UPDATE_DISH = "UPDATE dishes SET name = ?, price = ?, inventory = ? WHERE id = ?";
    private static final String SELECT_DISH = "SELECT * FROM dishes WHERE id = ?";

    public static void main(String[] args) {
        // 建立数据库连接
        try (Connection conn = DriverManager.getConnection(JDBC_URL, JDBC_USERNAME, JDBC_PASSWORD)) {
            // 添加一道新菜
            addDish(conn, "红烧肉", 28.0, 50);

            // 修改一道菜的信息
            updateDish(conn, 1, "红烧排骨", 32.0, 30);

            // 查询一道菜的信息
            Dish dish = selectDish(conn, 1);
            System.out.println(dish);

            // 删除一道菜
            deleteDish(conn, 1);
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    // 添加一道新菜
    private static void addDish(Connection conn, String name, double price, int inventory) throws SQLException {
        PreparedStatement stmt = conn.prepareStatement(INSERT_DISH, Statement.RETURN_GENERATED_KEYS);
        stmt.setString(1, name);
        stmt.setDouble(2, price);
        stmt.setInt(3, inventory);
        stmt.executeUpdate();

        ResultSet rs = stmt.getGeneratedKeys();
        if (rs.next()) {
            int id = rs.getInt(1);
            System.out.println("新增菜品成功，ID为" + id);
        }

        rs.close();
        stmt.close();
    }

    // 修改一道菜的信息
    private static void updateDish(Connection conn, int id, String name, double price, int inventory) throws SQLException {
        PreparedStatement stmt = conn.prepareStatement(UPDATE_DISH);
        stmt.setString(1, name);
        stmt.setDouble(2, price);
        stmt.setInt(3, inventory);
        stmt.setInt(4, id);
        int rows = stmt.executeUpdate();

        if (rows > 0) {
            System.out.println("修改菜品信息成功");
        }

        stmt.close();
    }

    // 查询一道菜的信息
    private static Dish selectDish(Connection conn, int id) throws SQLException {
        PreparedStatement stmt = conn.prepareStatement(SELECT_DISH);
        stmt.setInt(1, id);
        ResultSet rs = stmt.executeQuery();

        Dish dish = null;
        if (rs.next()) {
            String name = rs.getString("name");
            double price = rs.getDouble("price");
            int inventory = rs.getInt("inventory");
            dish = new Dish(id, name, price, inventory);
        }

        rs.close();
        stmt.close();

        return dish;
    }

    // 删除一道菜
    private static void deleteDish(Connection conn, int id) throws SQLException {
        PreparedStatement stmt = conn.prepareStatement(DELETE_DISH);
        stmt.setInt(1, id);
        int rows = stmt.executeUpdate();

        if (rows > 0) {
            System.out.println("删除菜品成功");
        }

        stmt.close();
    }

    // 菜品信息类
    private static class Dish {
        private int id;
        private String name;
        private double price;
        private int inventory;

        public Dish(int id, String name, double price, int inventory) {
            this.id = id;
            this.name = name;
            this.price = price;
            this.inventory = inventory;
        }

        public int getId() {
            return id;
        }

        public String getName() {
            return name;
        }

        public double getPrice() {
            return price;
        }

        public int getInventory() {
            return inventory;
        }

        @Override
        public String toString() {
            return "菜品信息：ID=" + id + ", 名称=" + name + ", 价格=" + price + ", 库存=" + inventory;
        }
    }
}

以上代码实现了食堂管理系统中的菜品信息的增删改查功能。您可以根据需要进行修改和扩展。