servlet与mysql数据库

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

public class MyServlet extends HttpServlet {
    private Connection conn;

    public void init() throws ServletException {
        try {
            Class.forName("com.mysql.cj.jdbc.Driver");
            String url = "jdbc:mysql://localhost:3306/mydatabase";
            String user = "username";
            String password = "password";
            conn = DriverManager.getConnection(url, user, password);
        } catch (ClassNotFoundException | SQLException e) {
            throw new ServletException("Database connection error", e);
        }
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        try (Statement stmt = conn.createStatement();
             ResultSet rs = stmt.executeQuery("SELECT * FROM mytable")) {
            PrintWriter out = response.getWriter();
            while (rs.next()) {
                out.println(rs.getString("columnName"));
            }
        } catch (SQLException e) {
            throw new ServletException("Database query error", e);
        }
    }

    public void destroy() {
        try {
            if (conn != null) {
                conn.close();
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}