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，这是一个典型的JDBC操作数据库的问题，我来给您提供一份样例代码，帮助您完成这个问题。

首先需要引入JDBC的jar包，这里我们以MySQL为例，需要引入mysql-connector-java.jar。

然后，您需要创建一个JDBCUtil类，用于建立与数据库的连接，以及执行SQL语句。

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

public class JDBCUtil {
    private static final String DRIVER = "com.mysql.jdbc.Driver";
    private static final String URL = "jdbc:mysql://localhost:3306/test?useSSL=false&useUnicode=true&characterEncoding=UTF-8";
    private static final String USERNAME = "root";
    private static final String PASSWORD = "123456";

    /**
     * 建立数据库连接
     *
     * @return
     */
    public static Connection getConnection() {
        Connection conn = null;
        try {
            Class.forName(DRIVER);
            conn = DriverManager.getConnection(URL, USERNAME, PASSWORD);
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return conn;
    }

    /**
     * 查询全部学生信息
     *
     * @return
     */
    public static ArrayList<Student> queryAllStudent() {
        ArrayList<Student> studentList = new ArrayList<>();
        Connection conn = getConnection();
        PreparedStatement pstmt = null;
        ResultSet rs = null;
        String sql = "SELECT * FROM student";
        try {
            pstmt = conn.prepareStatement(sql);
            rs = pstmt.executeQuery();
            while (rs.next()) {
                Student student = new Student();
                student.setId(rs.getInt("id"));
                student.setName(rs.getString("name"));
                student.setAge(rs.getInt("age"));
                studentList.add(student);
            }
        } 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();
            }
        }
        return studentList;
    }

    /**
     * 添加学生信息
     *
     * @param student
     * @return
     */
    public static int addStudent(Student student) {
        int result = 0;
        Connection conn = getConnection();
        PreparedStatement pstmt = null;
        String sql = "INSERT INTO student (name, age) VALUES (?, ?)";
        try {
            pstmt = conn.prepareStatement(sql);
            pstmt.setString(1, student.getName());
            pstmt.setInt(2, student.getAge());
            result = pstmt.executeUpdate();
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            try {
                if (pstmt != null) {
                    pstmt.close();
                }
                if (conn != null) {
                    conn.close();
                }
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        return result;
    }

    /**
     * 修改学生信息
     *
     * @param student
     * @return
     */
    public static int updateStudent(Student student) {
        int result = 0;
        Connection conn = getConnection();
        PreparedStatement pstmt = null;
        String sql = "UPDATE student SET name=?, age=? WHERE id=?";
        try {
            pstmt = conn.prepareStatement(sql);
            pstmt.setString(1, student.getName());
            pstmt.setInt(2, student.getAge());
            pstmt.setInt(3, student.getId());
            result = pstmt.executeUpdate();
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            try {
                if (pstmt != null) {
                    pstmt.close();
                }
                if (conn != null) {
                    conn.close();
                }
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        return result;
    }

    /**
     * 删除学生信息
     *
     * @param id
     * @return
     */
    public static int deleteStudent(int id) {
        int result = 0;
        Connection conn = getConnection();
        PreparedStatement pstmt = null;
        String sql = "DELETE FROM student WHERE id=?";
        try {
            pstmt = conn.prepareStatement(sql);
            pstmt.setInt(1, id);
            result = pstmt.executeUpdate();
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            try {
                if (pstmt != null) {
                    pstmt.close();
                }
                if (conn != null) {
                    conn.close();
                }
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        return result;
    }
}

其中，Student类是一个简单的JavaBean类，用于存储学生信息。

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

    // 省略getter和setter方法

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

接下来，您可以在任何需要操作数据库的地方，调用JDBCUtil类提供的方法，来完成对数据库的操作。

import java.util.ArrayList;

public class Test {
    public static void main(String[] args) {
        // 查询全部学生信息
        ArrayList<Student> studentList = JDBCUtil.queryAllStudent();
        System.out.println(studentList);

        // 添加学生信息
        Student student1 = new Student();
        student1.setName("Tom");
        student1.setAge(18);
        int result1 = JDBCUtil.addStudent(student1);
        System.out.println(result1);

        // 修改学生信息
        Student student2 = new Student();
        student2.setId(1);
        student2.setName("Jerry");
        student2.setAge(19);
        int result2 = JDBCUtil.updateStudent(student2);
        System.out.println(result2);

        // 删除学生信息
        int result3 = JDBCUtil.deleteStudent(2);
        System.out.println(result3);
    }
}

以上就是一个简单的利用JDBC操作数据库的样例代码，希望对您有所帮助。