mysql的分库分表

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

public class ShardingExample {
    private static final String DB_URL = "jdbc:mysql://localhost:3306/mydb";
    private static final String USER = "user";
    private static final String PASS = "password";

    public static void main(String[] args) {
        String userId = "123456";
        String tableName = getTableName(userId);
        saveUser(userId, "John Doe");
        String name = getUser(userId);
        System.out.println("User name: " + name);
    }

    private static String getTableName(String userId) {
        int hash = Math.abs(userId.hashCode());
        return "user_table_" + (hash % 10);
    }

    private static void saveUser(String userId, String name) {
        String tableName = getTableName(userId);
        String sql = "INSERT INTO " + tableName + " (user_id, name) VALUES (?, ?)";
        try (Connection conn = DriverManager.getConnection(DB_URL, USER, PASS);
             PreparedStatement ps = conn.prepareStatement(sql)) {
            ps.setString(1, userId);
            ps.setString(2, name);
            ps.executeUpdate();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    private static String getUser(String userId) {
        String tableName = getTableName(userId);
        String sql = "SELECT name FROM " + tableName + " WHERE user_id = ?";
        try (Connection conn = DriverManager.getConnection(DB_URL, USER, PASS);
             PreparedStatement ps = conn.prepareStatement(sql)) {
            ps.setString(1, userId);
            ResultSet rs = ps.executeQuery();
            if (rs.next()) {
                return rs.getString("name");
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return null;
    }
}