如何在Java中从指定表中返回列计数、列名和列类型？

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

public class Main {
    public static void main(String[] args) {
        String url = "jdbc:mysql://localhost:3306/mydatabase";
        String username = "root";
        String password = "password";

        try {
            Connection connection = DriverManager.getConnection(url, username, password);
            // 连接成功后的操作
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

import java.sql.*;

public class Main {
    public static void main(String[] args) {
        String url = "jdbc:mysql://localhost:3306/mydatabase";
        String username = "root";
        String password = "password";

        try {
            Connection connection = DriverManager.getConnection(url, username, password);
            Statement statement = connection.createStatement();
            String query = "SELECT * FROM mytable";
            ResultSet resultSet = statement.executeQuery(query);

            ResultSetMetaData metaData = resultSet.getMetaData();
            int columnCount = metaData.getColumnCount();
            for (int i = 1; i <= columnCount; i++) {
                String columnName = metaData.getColumnName(i);
                String columnType = metaData.getColumnTypeName(i);
                System.out.println("Column " + i + ": " + columnName + " (" + columnType + ")");
            }

            resultSet.close();
            statement.close();
            connection.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}