从java类中的sql中检索数据

import java.sql.*;

public class RetrieveDataExample {
    public static void main(String[] args) {
        Connection connection = null;
        Statement statement = null;
        ResultSet resultSet = null;

        try {
            // 加载数据库驱动程序
            Class.forName("com.mysql.jdbc.Driver");

            // 建立数据库连接
            connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/mydatabase", "username", "password");

            // 创建SQL语句
            String sql = "SELECT * FROM mytable";

            // 执行SQL查询
            statement = connection.createStatement();
            resultSet = statement.executeQuery(sql);

            // 处理查询结果
            while (resultSet.next()) {
                String column1 = resultSet.getString("column1");
                int column2 = resultSet.getInt("column2");
                // 处理获取到的数据
            }
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            // 关闭数据库连接
            try {
                if (resultSet != null) {
                    resultSet.close();
                }
                if (statement != null) {
                    statement.close();
                }
                if (connection != null) {
                    connection.close();
                }
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
}