jsp连接mysql数据库javabean

<%@ page import="java.sql.*" %>
<%
    Class.forName("com.mysql.jdbc.Driver");
%>

<%
    String url = "jdbc:mysql://localhost:3306/数据库名";
    String username = "数据库用户名";
    String password = "数据库密码";
    Connection conn = DriverManager.getConnection(url, username, password);
%>

import java.sql.*;

public class DBHelper {
    private Connection conn;
    private Statement stmt;
    private ResultSet rs;

    public DBHelper() {
        String url = "jdbc:mysql://localhost:3306/数据库名";
        String username = "数据库用户名";
        String password = "数据库密码";
        try {
            Class.forName("com.mysql.jdbc.Driver");
            conn = DriverManager.getConnection(url, username, password);
            stmt = conn.createStatement();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public ResultSet executeQuery(String sql) {
        try {
            rs = stmt.executeQuery(sql);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return rs;
    }

    public int executeUpdate(String sql) {
        int result = 0;
        try {
            result = stmt.executeUpdate(sql);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return result;
    }

    public void close() {
        try {
            if (rs != null) {
                rs.close();
            }
            if (stmt != null) {
                stmt.close();
            }
            if (conn != null) {
                conn.close();
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

<%
    DBHelper dbHelper = new DBHelper();
    String sql = "SELECT * FROM 表名";
    ResultSet rs = dbHelper.executeQuery(sql);
    while (rs.next()) {
        // 处理查询结果
        out.println(rs.getString("列名"));
    }
    rs.close();
    dbHelper.close();
%>