servlet mysql查询

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

public class MyServlet extends HttpServlet {
    private static final String DB_URL = "jdbc:mysql://localhost:3306/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;
        ResultSet rs = null;

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

            // 打开连接
            conn = DriverManager.getConnection(DB_URL, USER, PASS);

            // 执行查询
            stmt = conn.createStatement();
            String sql = "SELECT id, name, age FROM users";
            rs = stmt.executeQuery(sql);

            // 处理结果集
            PrintWriter out = response.getWriter();
            while (rs.next()) {
                int id = rs.getInt("id");
                String name = rs.getString("name");
                int age = rs.getInt("age");
                out.println("ID: " + id + ", Name: " + name + ", Age: " + age + "<br>");
            }
        } catch (SQLException se) {
            se.printStackTrace();
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            // 关闭资源
            try {
                if (rs != null) rs.close();
            } catch (SQLException se2) {
            }
            try {
                if (stmt != null) stmt.close();
            } catch (SQLException se2) {
            }
            try {
                if (conn != null) conn.close();
            } catch (SQLException se) {
                se.printStackTrace();
            }
        }
    }
}