上面的jsp页面中的“conn = DriverManager.getConnection(url, username, password);”、“Students student = new Students();”和“studentsList.add(students);”这三条语句报错了，是需要导什么包 ？还是其他的问题？应该怎么修改才能使这个jsp页面能够运行呢？

这三条语句报错可能是因为缺少相关的类或包，你需要导入以下包：

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

另外，由于你使用了 `Students` 类和 `studentsList` 变量，所以你还需要定义这个类和变量，并且在添加学生信息时要确保已经实例化了 `Students` 类。

修改后的代码如下：

<%@ page import="java.sql.*, java.util.*" %>
<%
    String driver = "com.mysql.jdbc.Driver";
    String url = "jdbc:mysql://localhost:3306/test";
    String username = "root";
    String password = "root";
    Connection conn = null;
    PreparedStatement pstmt = null;
    ResultSet rs = null;
    List<Students> studentsList = new ArrayList<Students>(); // 定义学生列表

    try {
        Class.forName(driver);
        conn = DriverManager.getConnection(url, username, password);
        String sql = "SELECT * FROM students";
        pstmt = conn.prepareStatement(sql);
        rs = pstmt.executeQuery();

        while (rs.next()) {
            Students student = new Students(); // 实例化学生对象
            student.setId(rs.getInt("id"));
            student.setName(rs.getString("name"));
            student.setAge(rs.getInt("age"));
            studentsList.add(student); // 添加到学生列表
        }
    } catch (ClassNotFoundException e) {
        e.printStackTrace();
    } catch (SQLException e) {
        e.printStackTrace();
    } finally {
        try {
            if (rs != null) {
                rs.close();
            }
            if (pstmt != null) {
                pstmt.close();
            }
            if (conn != null) {
                conn.close();
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    // 输出学生列表
    for (Students student : studentsList) {
        out.println("学生姓名：" + student.getName() + "，年龄：" + student.getAge() + "<br>");
    }

    // 定义 Students 类
    class Students {
        private int id;
        private String name;
        private int age;

        public int getId() {
            return id;
        }

        public void setId(int id) {
            this.id = id;
        }

        public String getName() {
            return name;
        }

        public void setName(String name) {
            this.name = name;
        }

        public int getAge() {
            return age;
        }

        public void setAge(int age) {
            this.age = age;
        }
    }
%>