创建一个JDBC类，其主要包括了创建与数据库的连接，查询全部学生信息，添加学生信息，修改学生信息和删除学生信息等方法并将返回的结果集封装到ArrayList中

好的，以下是一个简单的 JDBC 工具类，包含了连接数据库、查询全部学生信息、添加学生信息、修改学生信息和删除学生信息的方法，并将返回的结果集封装到 ArrayList 中：

import java.sql.*;
import java.util.ArrayList;

public class JDBCUtil {
    // 数据库连接信息
    private static final String DRIVER_CLASS = "com.mysql.jdbc.Driver";
    private static final String URL = "jdbc:mysql://localhost:3306/test";
    private static final String USER = "root";
    private static final String PASSWORD = "root";

    // 加载数据库驱动
    static {
        try {
            Class.forName(DRIVER_CLASS);
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
    }

    // 获取数据库连接
    public static Connection getConnection() throws SQLException {
        return DriverManager.getConnection(URL, USER, PASSWORD);
    }

    // 查询全部学生信息
    public static ArrayList<Student> getAllStudents() throws SQLException {
        ArrayList<Student> students = new ArrayList<>();
        try (Connection conn = getConnection();
             Statement stmt = conn.createStatement();
             ResultSet rs = stmt.executeQuery("SELECT * FROM student")) {
            while (rs.next()) {
                Student student = new Student();
                student.setId(rs.getInt("id"));
                student.setName(rs.getString("name"));
                student.setAge(rs.getInt("age"));
                student.setGrade(rs.getInt("grade"));
                students.add(student);
            }
        }
        return students;
    }

    // 添加学生信息
    public static boolean addStudent(Student student) throws SQLException {
        try (Connection conn = getConnection();
             PreparedStatement stmt = conn.prepareStatement("INSERT INTO student (name, age, grade) VALUES (?, ?, ?)")) {
            stmt.setString(1, student.getName());
            stmt.setInt(2, student.getAge());
            stmt.setInt(3, student.getGrade());
            return stmt.executeUpdate() > 0;
        }
    }

    // 修改学生信息
    public static boolean updateStudent(Student student) throws SQLException {
        try (Connection conn = getConnection();
             PreparedStatement stmt = conn.prepareStatement("UPDATE student SET name=?, age=?, grade=? WHERE id=?")) {
            stmt.setString(1, student.getName());
            stmt.setInt(2, student.getAge());
            stmt.setInt(3, student.getGrade());
            stmt.setInt(4, student.getId());
            return stmt.executeUpdate() > 0;
        }
    }

    // 删除学生信息
    public static boolean deleteStudent(int id) throws SQLException {
        try (Connection conn = getConnection();
             PreparedStatement stmt = conn.prepareStatement("DELETE FROM student WHERE id=?")) {
            stmt.setInt(1, id);
            return stmt.executeUpdate() > 0;
        }
    }
}

其中，`Student` 是一个简单的 JavaBean，包含了 id、name、age 和 grade 四个属性。

public class Student {
    private int id;
    private String name;
    private int age;
    private int grade;

    // getter 和 setter 方法省略...

    @Override
    public String toString() {
        return "Student{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", age=" + age +
                ", grade=" + grade +
                '}';
    }
}

使用示例：

public class Main {
    public static void main(String[] args) throws SQLException {
        // 查询全部学生信息
        ArrayList<Student> students = JDBCUtil.getAllStudents();
        System.out.println("All students: " + students);

        // 添加学生信息
        Student newStudent = new Student();
        newStudent.setName("Tom");
        newStudent.setAge(20);
        newStudent.setGrade(90);
        System.out.println("Add student result: " + JDBCUtil.addStudent(newStudent));

        // 查询全部学生信息
        students = JDBCUtil.getAllStudents();
        System.out.println("All students: " + students);

        // 修改学生信息
        Student updateStudent = students.get(0);
        updateStudent.setName("Jerry");
        updateStudent.setAge(21);
        updateStudent.setGrade(80);
        System.out.println("Update student result: " + JDBCUtil.updateStudent(updateStudent));

        // 查询全部学生信息
        students = JDBCUtil.getAllStudents();
        System.out.println("All students: " + students);

        // 删除学生信息
        int deleteStudentId = students.get(0).getId();
        System.out.println("Delete student result: " + JDBCUtil.deleteStudent(deleteStudentId));

        // 查询全部学生信息
        students = JDBCUtil.getAllStudents();
        System.out.println("All students: " + students);
    }
}