java mysql退票系统包括dao层，service层，view层

好的，针对Java MySQL退票系统，下面是一个简单的DAO层、Service层和View层的实现：

1. DAO层

DAO层负责与数据库进行交互，主要包括查询、更新、插入和删除数据等操作。在这里我们以订单为例，创建一个OrderDAO类来实现相关操作：

public class OrderDAO {
    private Connection conn;

    public OrderDAO(Connection conn) {
        this.conn = conn;
    }

    // 查询订单信息
    public Order findOrderById(int orderId) throws SQLException {
        Order order = null;
        String sql = "SELECT * FROM orders WHERE order_id = ?";
        try (PreparedStatement stmt = conn.prepareStatement(sql)) {
            stmt.setInt(1, orderId);
            try (ResultSet rs = stmt.executeQuery()) {
                if (rs.next()) {
                    order = new Order();
                    order.setOrderId(rs.getInt("order_id"));
                    order.setUserId(rs.getInt("user_id"));
                    order.setStatus(rs.getString("status"));
                    order.setAmount(rs.getDouble("amount"));
                }
            }
        }
        return order;
    }

    // 更新订单状态
    public void updateOrderStatus(int orderId, String status) throws SQLException {
        String sql = "UPDATE orders SET status = ? WHERE order_id = ?";
        try (PreparedStatement stmt = conn.prepareStatement(sql)) {
            stmt.setString(1, status);
            stmt.setInt(2, orderId);
            stmt.executeUpdate();
        }
    }

    // 插入订单信息
    public void insertOrder(Order order) throws SQLException {
        String sql = "INSERT INTO orders (user_id, amount, status) VALUES (?, ?, ?)";
        try (PreparedStatement stmt = conn.prepareStatement(sql, Statement.RETURN_GENERATED_KEYS)) {
            stmt.setInt(1, order.getUserId());
            stmt.setDouble(2, order.getAmount());
            stmt.setString(3, order.getStatus());
            stmt.executeUpdate();
            try (ResultSet rs = stmt.getGeneratedKeys()) {
                if (rs.next()) {
                    order.setOrderId(rs.getInt(1));
                }
            }
        }
    }

    // 删除订单信息
    public void deleteOrder(int orderId) throws SQLException {
        String sql = "DELETE FROM orders WHERE order_id = ?";
        try (PreparedStatement stmt = conn.prepareStatement(sql)) {
            stmt.setInt(1, orderId);
            stmt.executeUpdate();
        }
    }
}

2. Service层

Service层负责业务逻辑的处理，主要包括对DAO层的调用和数据处理等。在这里我们以OrderService类来实现相关操作：

public class OrderService {
    private OrderDAO orderDAO;

    public OrderService(OrderDAO orderDAO) {
        this.orderDAO = orderDAO;
    }

    // 查询订单信息
    public Order findOrderById(int orderId) throws SQLException {
        return orderDAO.findOrderById(orderId);
    }

    // 更新订单状态
    public void updateOrderStatus(int orderId, String status) throws SQLException {
        orderDAO.updateOrderStatus(orderId, status);
    }

    // 插入订单信息
    public void insertOrder(Order order) throws SQLException {
        orderDAO.insertOrder(order);
    }

    // 删除订单信息
    public void deleteOrder(int orderId) throws SQLException {
        orderDAO.deleteOrder(orderId);
    }

    // 根据用户ID查询订单信息
    public List<Order> findOrdersByUserId(int userId) throws SQLException {
        List<Order> orders = new ArrayList<>();
        String sql = "SELECT * FROM orders WHERE user_id = ?";
        try (PreparedStatement stmt = orderDAO.getConnection().prepareStatement(sql)) {
            stmt.setInt(1, userId);
            try (ResultSet rs = stmt.executeQuery()) {
                while (rs.next()) {
                    Order order = new Order();
                    order.setOrderId(rs.getInt("order_id"));
                    order.setUserId(rs.getInt("user_id"));
                    order.setStatus(rs.getString("status"));
                    order.setAmount(rs.getDouble("amount"));
                    orders.add(order);
                }
            }
        }
        return orders;
    }
}

在OrderService中，我们调用了OrderDAO的相关操作，同时还添加了根据用户ID查询订单信息的方法。

3. View层

View层负责与用户进行交互，主要包括数据的展示和用户的输入等。在这里我们以控制台界面来实现相关操作：

public class OrderView {
    private OrderService orderService;

    public OrderView(OrderService orderService) {
        this.orderService = orderService;
    }

    public void showMenu() {
        System.out.println("1. 查询订单");
        System.out.println("2. 更新订单状态");
        System.out.println("3. 插入订单");
        System.out.println("4. 删除订单");
        System.out.println("5. 查询用户订单");
        System.out.println("0. 退出");
    }

    public void run() throws IOException, SQLException {
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        while (true) {
            showMenu();
            System.out.print("请选择操作：");
            String option = reader.readLine();
            if (option.equals("1")) {
                System.out.print("请输入订单号：");
                int orderId = Integer.parseInt(reader.readLine());
                Order order = orderService.findOrderById(orderId);
                if (order != null) {
                    System.out.println(order);
                } else {
                    System.out.println("订单不存在");
                }
            } else if (option.equals("2")) {
                System.out.print("请输入订单号：");
                int orderId = Integer.parseInt(reader.readLine());
                System.out.print("请输入订单状态：");
                String status = reader.readLine();
                orderService.updateOrderStatus(orderId, status);
            } else if (option.equals("3")) {
                System.out.print("请输入用户ID：");
                int userId = Integer.parseInt(reader.readLine());
                System.out.print("请输入订单金额：");
                double amount = Double.parseDouble(reader.readLine());
                Order order = new Order();
                order.setUserId(userId);
                order.setAmount(amount);
                order.setStatus("未支付");
                orderService.insertOrder(order);
                System.out.println("订单已生成，订单号为：" + order.getOrderId());
            } else if (option.equals("4")) {
                System.out.print("请输入订单号：");
                int orderId = Integer.parseInt(reader.readLine());
                orderService.deleteOrder(orderId);
                System.out.println("订单已删除");
            } else if (option.equals("5")) {
                System.out.print("请输入用户ID：");
                int userId = Integer.parseInt(reader.readLine());
                List<Order> orders = orderService.findOrdersByUserId(userId);
                if (orders.isEmpty()) {
                    System.out.println("用户没有订单");
                } else {
                    for (Order order : orders) {
                        System.out.println(order);
                    }
                }
            } else if (option.equals("0")) {
                break;
            } else {
                System.out.println("无效操作");
            }
        }
    }
}

在OrderView中，我们通过控制台界面展示菜单，并根据用户的输入调用OrderService的相关方法进行操作。同时注意要处理异常，以保证程序的稳定性。