mysql和tomcat存在兼容问题

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.sql.*;

public class MyServlet extends HttpServlet {
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        Connection conn = null;
        Statement stmt = null;
        ResultSet rs = null;

        try {
            // 加载JDBC驱动
            Class.forName("com.mysql.cj.jdbc.Driver");

            // 连接数据库
            String url = "jdbc:mysql://localhost:3306/mydatabase";
            String user = "username";
            String password = "password";
            conn = DriverManager.getConnection(url, user, password);

            // 执行查询
            stmt = conn.createStatement();
            rs = stmt.executeQuery("SELECT * FROM mytable");

            // 处理结果集
            while (rs.next()) {
                System.out.println(rs.getString("columnName"));
            }
        } catch (ClassNotFoundException | SQLException e) {
            e.printStackTrace();
        } finally {
            try {
                if (rs != null) rs.close();
                if (stmt != null) stmt.close();
                if (conn != null) conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
}