tomcat 连mysql

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

public class MyServlet extends HttpServlet {
    private static final String DB_URL = "jdbc:mysql://localhost/mydatabase";
    private static final String USER = "username";
    private static final String PASS = "password";

    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        Connection conn = null;
        Statement stmt = null;
        try {
            // 注册 JDBC 驱动
            Class.forName("com.mysql.cj.jdbc.Driver");

            // 打开连接
            System.out.println("连接数据库...");
            conn = DriverManager.getConnection(DB_URL, USER, PASS);

            // 执行查询
            System.out.println("实例化Statement对象...");
            stmt = conn.createStatement();
            String sql;
            sql = "SELECT id, name, age FROM employees";
            ResultSet rs = stmt.executeQuery(sql);

            // 提取数据
            while (rs.next()) {
                int id = rs.getInt("id");
                String name = rs.getString("name");
                int age = rs.getInt("age");

                // 显示数据
                System.out.println("ID: " + id);
                System.out.println("NAME: " + name);
                System.out.println("AGE: " + age);
            }
            // 清理环境
            rs.close();
            stmt.close();
            conn.close();
        } catch (SQLException se) {
            // 处理 JDBC 错误
            se.printStackTrace();
        } catch (Exception e) {
            // 处理 Class.forName 错误
            e.printStackTrace();
        } finally {
            // 关闭资源
            try {
                if (stmt != null) stmt.close();
            } catch (SQLException se2) {
            }
            try {
                if (conn != null) conn.close();
            } catch (SQLException se) {
                se.printStackTrace();
            }
        }
        response.getWriter().println("数据库操作完成!");
    }
}