场景：针对一些特别的项目，不用中间件，以月为维度进行分表，代码详细设计方案

1. 定义分片策略

首先，定义一个分片策略类，用于决定数据存储在哪个分表中

import java.time.LocalDate;
import java.time.format.DateTimeFormatter;

public class ShardingStrategy {
    private static final DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy_MM");

    public String getShardId(LocalDate date) {
        return date.format(formatter);
    }
}

2. 数据库连接管理

创建一个数据库连接管理类，用于管理数据库连接

import java.sql.Connection;
import java.sql.DriverManager;

public class DatabaseManager {
    private static Connection connection;

    static {
        try {
            Class.forName("com.mysql.cj.jdbc.Driver");
            connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/mydatabase", "user", "password");
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public static Connection getConnection() {
        return connection;
    }
}

3. 动态创建表

创建一个方法，用于根据当前月份动态创建新的表

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import java.time.LocalDate;

public class TableCreator {
    private ShardingStrategy shardingStrategy = new ShardingStrategy();

    public void createTableForMonth(LocalDate date) {
        String shardId = shardingStrategy.getShardId(date);
        String tableName = "orders_" + shardId;
        Connection connection = DatabaseManager.getConnection();

        String createTableSQL = "CREATE TABLE IF NOT EXISTS " + tableName + " ("
                + "id BIGINT PRIMARY KEY,"
                + "order_date DATE,"
                + "customer_name VARCHAR(255)"
                + ")";

        try (PreparedStatement statement = connection.prepareStatement(createTableSQL)) {
            statement.execute();
            System.out.println("Table " + tableName + " created successfully.");
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

4. 订单操作类

创建一个订单操作类，用于执行具体的数据库操作。这里根据分片策略动态生成表名

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.time.LocalDate;

public class OrderDAO {
    private ShardingStrategy shardingStrategy = new ShardingStrategy();
    private TableCreator tableCreator = new TableCreator();

    public void createOrder(long orderId, LocalDate orderDate, String customerName) {
        // 确保表存在
        tableCreator.createTableForMonth(orderDate);

        String shardId = shardingStrategy.getShardId(orderDate);
        String tableName = "orders_" + shardId;
        Connection connection = DatabaseManager.getConnection();

        try (PreparedStatement statement = connection.prepareStatement(
                "INSERT INTO " + tableName + " (id, order_date, customer_name) VALUES (?, ?, ?)")) {
            statement.setLong(1, orderId);
            statement.setDate(2, java.sql.Date.valueOf(orderDate));
            statement.setString(3, customerName);
            statement.executeUpdate();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    public String getCustomerNameByOrderId(long orderId, LocalDate orderDate) {
        String shardId = shardingStrategy.getShardId(orderDate);
        String tableName = "orders_" + shardId;
        Connection connection = DatabaseManager.getConnection();

        try (PreparedStatement statement = connection.prepareStatement(
                "SELECT customer_name FROM " + tableName + " WHERE id = ?")) {
            statement.setLong(1, orderId);
            ResultSet resultSet = statement.executeQuery();
            if (resultSet.next()) {
                return resultSet.getString("customer_name");
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return null;
    }
}

5. 使用示例

最后，展示如何使用上述类来创建订单和查询订单信息

public class Main {
    public static void main(String[] args) {
        OrderDAO orderDAO = new OrderDAO();

        // 创建订单
        orderDAO.createOrder(1, LocalDate.of(2023, 1, 15), "Alice");
        orderDAO.createOrder(2, LocalDate.of(2023, 2, 20), "Bob");
        orderDAO.createOrder(3, LocalDate.of(2023, 3, 10), "Charlie");

        // 查询订单
        System.out.println("Order ID 1: " + orderDAO.getCustomerNameByOrderId(1, LocalDate.of(2023, 1, 15)));
        System.out.println("Order ID 2: " + orderDAO.getCustomerNameByOrderId(2, LocalDate.of(2023, 2, 20)));
        System.out.println("Order ID 3: " + orderDAO.getCustomerNameByOrderId(3, LocalDate.of(2023, 3, 10)));
    }
}

总结

• 分片策略：根据订单日期决定数据存储在哪个分表中。
• 数据库连接管理：管理数据库连接，所有分表都在同一个数据库中。
• 动态创建表：根据当前月份动态创建新的表。
• 订单操作：执行具体的数据库操作，如插入和查询。通过动态生成表名来实现分表。
• 使用示例：展示如何使用这些类来实现分表功能。

这个方案适用于在同一数据库中按月份进行分表的需求，可以根据实际业务场景进一步扩展和优化。