Java连接数据库写一个产品销售项目

好的，以下是一个简单的Java连接数据库的产品销售项目的示例：

1. 创建一个名为Product的Java类，表示产品实体，包括属性id、name、description、price和quantity。

public class Product {
    private int id;
    private String name;
    private String description;
    private double price;
    private int quantity;
    
    public Product(int id, String name, String description, double price, int quantity) {
        this.id = id;
        this.name = name;
        this.description = description;
        this.price = price;
        this.quantity = quantity;
    }
    
    // getter and setter methods
}

2. 创建一个名为ProductDAO的Java类，用于执行与数据库交互的操作，包括连接到数据库、插入产品、更新产品、删除产品和获取所有产品等操作。

import java.sql.*;
import java.util.ArrayList;
import java.util.List;

public class ProductDAO {
    private String jdbcURL;
    private String jdbcUsername;
    private String jdbcPassword;
    private Connection jdbcConnection;
    
    public ProductDAO(String jdbcURL, String jdbcUsername, String jdbcPassword) {
        this.jdbcURL = jdbcURL;
        this.jdbcUsername = jdbcUsername;
        this.jdbcPassword = jdbcPassword;
    }
    
    //连接数据库
    protected void connect() throws SQLException {
        if (jdbcConnection == null || jdbcConnection.isClosed()) {
            try {
                Class.forName("com.mysql.cj.jdbc.Driver");
            } catch (ClassNotFoundException e) {
                throw new SQLException(e);
            }
            jdbcConnection = DriverManager.getConnection(
                    jdbcURL, jdbcUsername, jdbcPassword);
        }
    }
    
    //断开数据库连接
    protected void disconnect() throws SQLException {
        if (jdbcConnection != null && !jdbcConnection.isClosed()) {
            jdbcConnection.close();
        }
    }
    
    //插入产品
    public boolean insertProduct(Product product) throws SQLException {
        String sql = "INSERT INTO product (name, description, price, quantity) VALUES (?, ?, ?, ?)";
        connect();
        
        PreparedStatement statement = jdbcConnection.prepareStatement(sql);
        statement.setString(1, product.getName());
        statement.setString(2, product.getDescription());
        statement.setDouble(3, product.getPrice());
        statement.setInt(4, product.getQuantity());
        
        boolean rowInserted = statement.executeUpdate() > 0;
        statement.close();
        disconnect();
        return rowInserted;
    }
    
    //更新产品
    public boolean updateProduct(Product product) throws SQLException {
        String sql = "UPDATE product SET name = ?, description = ?, price = ?, quantity = ? WHERE id = ?";
        connect();
        
        PreparedStatement statement = jdbcConnection.prepareStatement(sql);
        statement.setString(1, product.getName());
        statement.setString(2, product.getDescription());
        statement.setDouble(3, product.getPrice());
        statement.setInt(4, product.getQuantity());
        statement.setInt(5, product.getId());
        
        boolean rowUpdated = statement.executeUpdate() > 0;
        statement.close();
        disconnect();
        return rowUpdated;
    }
    
    //删除产品
    public boolean deleteProduct(Product product) throws SQLException {
        String sql = "DELETE FROM product WHERE id = ?";
        connect();
        
        PreparedStatement statement = jdbcConnection.prepareStatement(sql);
        statement.setInt(1, product.getId());
        
        boolean rowDeleted = statement.executeUpdate() > 0;
        statement.close();
        disconnect();
        return rowDeleted;
    }
    
    //获取所有产品
    public List<Product> getAllProducts() throws SQLException {
        List<Product> products = new ArrayList<>();
        String sql = "SELECT * FROM product";
        connect();
        
        Statement statement = jdbcConnection.createStatement();
        ResultSet resultSet = statement.executeQuery(sql);
        
        while (resultSet.next()) {
            int id = resultSet.getInt("id");
            String name = resultSet.getString("name");
            String description = resultSet.getString("description");
            double price = resultSet.getDouble("price");
            int quantity = resultSet.getInt("quantity");
            
            Product product = new Product(id, name, description, price, quantity);
            products.add(product);
        }
        
        resultSet.close();
        statement.close();
        disconnect();
        
        return products;
    }
}

3. 创建一个名为ProductApp的Java类，包括主方法，用于测试ProductDAO的各种操作。

import java.sql.SQLException;
import java.util.List;

public class ProductApp {
    public static void main(String[] args) {
        String jdbcURL = "jdbc:mysql://localhost:3306/productdb?useSSL=false";
        String jdbcUsername = "root";
        String jdbcPassword = "password";
        
        ProductDAO productDAO = new ProductDAO(jdbcURL, jdbcUsername, jdbcPassword);
        
        try {
            //插入产品
            Product newProduct = new Product(1, "iPhone 12", "A14 Bionic chip, Super Retina XDR display", 999.0, 10);
            productDAO.insertProduct(newProduct);
            
            //更新产品
            Product existingProduct = new Product(1, "iPhone 12 Pro", "A14 Bionic chip, Pro camera system", 1099.0, 5);
            productDAO.updateProduct(existingProduct);
            
            //删除产品
            Product deletedProduct = new Product(1, "", "", 0.0, 0);
            productDAO.deleteProduct(deletedProduct);
            
            //获取所有产品
            List<Product> products = productDAO.getAllProducts();
            for (Product product : products) {
                System.out.println(product.getName());
            }
        } catch (SQLException ex) {
            ex.printStackTrace();
        }
    }
}

这是一个简单的Java连接数据库的产品销售项目示例，你可以根据自己的需求进行修改和扩展。