如何在Java中实现大型自定义游标？

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

public class CustomCursor {
    private Connection connection;
    private Statement statement;
    private ResultSet resultSet;
    
    public void open() throws SQLException {
        // 建立数据库连接
        connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/mydatabase", "username", "password");
        
        // 创建Statement对象
        statement = connection.createStatement();
        
        // 执行查询语句
        resultSet = statement.executeQuery("SELECT * FROM mytable");
    }
    
    public void fetchNext() throws SQLException {
        // 移动游标位置
        if (resultSet.next()) {
            // 获取当前位置的数据
            int id = resultSet.getInt("id");
            String name = resultSet.getString("name");
            
            // 处理数据
            System.out.println("ID: " + id + ", Name: " + name);
        }
    }
    
    public void close() throws SQLException {
        // 释放资源
        resultSet.close();
        statement.close();
        connection.close();
    }
}

CustomCursor cursor = new CustomCursor();
cursor.open();

while (/* 判断游标是否还有数据 */) {
    cursor.fetchNext();
}

cursor.close();