将Student对象(属性：int id, String name(不多于10个字符),int age,double grade)写入文件、读出文件，分别尝试使用以下方式实现： (1)DataInputStream, DataOutputStream； (2)Scanner(或BufferedReader), PrintWriter； (3)ObjectInputStream, ObjectOutputStream。 问题：1、2、3方法生成的文件大小各是多少？尝试分析1和2输出的文件大小。 要求：以方法的形式进行封装（使用方法重载），例如： public static void writeStudent(Student s, DataOutputStream dos){}; 或者：public static void writeStudent(List stus, DataOutputStream dos){}; 读取时类似： public static Student readStudent(DataInputStream dis){}; 或者：public static List readStudent(DataInputStream dis){};

以下是三种方式的实现，以及方法封装：

import java.io.*;
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

public class StudentFile {

    // 使用 DataOutputStream 写入单个 Student 对象
    public static void writeStudent(Student s, DataOutputStream dos) throws IOException {
        dos.writeInt(s.getId());
        dos.writeUTF(s.getName());
        dos.writeInt(s.getAge());
        dos.writeDouble(s.getGrade());
        dos.flush();
    }

    // 使用 DataOutputStream 写入多个 Student 对象
    public static void writeStudent(List<Student> stus, DataOutputStream dos) throws IOException {
        dos.writeInt(stus.size());
        for (Student s : stus) {
            writeStudent(s, dos);
        }
        dos.flush();
    }

    // 使用 DataInputStream 读取单个 Student 对象
    public static Student readStudent(DataInputStream dis) throws IOException {
        int id = dis.readInt();
        String name = dis.readUTF();
        int age = dis.readInt();
        double grade = dis.readDouble();
        return new Student(id, name, age, grade);
    }

    // 使用 DataInputStream 读取多个 Student 对象
    public static List<Student> readStudents(DataInputStream dis) throws IOException {
        int n = dis.readInt();
        List<Student> stus = new ArrayList<>();
        for (int i = 0; i < n; i++) {
            stus.add(readStudent(dis));
        }
        return stus;
    }

    // 使用 PrintWriter 写入单个 Student 对象
    public static void writeStudent(Student s, PrintWriter pw) {
        pw.println(s.getId());
        pw.println(s.getName());
        pw.println(s.getAge());
        pw.println(s.getGrade());
        pw.flush();
    }

    // 使用 PrintWriter 写入多个 Student 对象
    public static void writeStudent(List<Student> stus, PrintWriter pw) {
        pw.println(stus.size());
        for (Student s : stus) {
            writeStudent(s, pw);
        }
        pw.flush();
    }

    // 使用 Scanner 读取单个 Student 对象
    public static Student readStudent(Scanner scanner) {
        int id = scanner.nextInt();
        String name = scanner.next();
        int age = scanner.nextInt();
        double grade = scanner.nextDouble();
        return new Student(id, name, age, grade);
    }

    // 使用 Scanner 读取多个 Student 对象
    public static List<Student> readStudents(Scanner scanner) {
        int n = scanner.nextInt();
        List<Student> stus = new ArrayList<>();
        for (int i = 0; i < n; i++) {
            stus.add(readStudent(scanner));
        }
        return stus;
    }

    // 使用 ObjectOutputStream 写入多个 Student 对象
    public static void writeStudent(List<Student> stus, ObjectOutputStream oos) throws IOException {
        oos.writeObject(stus);
        oos.flush();
    }

    // 使用 ObjectInputStream 读取多个 Student 对象
    @SuppressWarnings("unchecked")
    public static List<Student> readStudents(ObjectInputStream ois) throws IOException, ClassNotFoundException {
        return (List<Student>) ois.readObject();
    }

    // 测试方法
    public static void main(String[] args) throws IOException, ClassNotFoundException {
        List<Student> stus = new ArrayList<>();
        stus.add(new Student(1, "Tom", 18, 90.5));
        stus.add(new Student(2, "Jerry", 19, 88.5));
        stus.add(new Student(3, "Bob", 20, 85.0));

        // 使用 DataOutputStream 写入多个 Student 对象
        ByteArrayOutputStream baos1 = new ByteArrayOutputStream();
        DataOutputStream dos1 = new DataOutputStream(baos1);
        writeStudent(stus, dos1);
        System.out.println("使用 DataOutputStream 写入多个 Student 对象，文件大小：" + baos1.size() + " 字节");

        // 使用 PrintWriter 写入多个 Student 对象
        ByteArrayOutputStream baos2 = new ByteArrayOutputStream();
        PrintWriter pw2 = new PrintWriter(new OutputStreamWriter(baos2));
        writeStudent(stus, pw2);
        System.out.println("使用 PrintWriter 写入多个 Student 对象，文件大小：" + baos2.size() + " 字节");

        // 使用 ObjectOutputStream 写入多个 Student 对象
        ByteArrayOutputStream baos3 = new ByteArrayOutputStream();
        ObjectOutputStream oos3 = new ObjectOutputStream(baos3);
        writeStudent(stus, oos3);
        System.out.println("使用 ObjectOutputStream 写入多个 Student 对象，文件大小：" + baos3.size() + " 字节");

        // 使用 DataInputStream 读取多个 Student 对象
        ByteArrayInputStream bais1 = new ByteArrayInputStream(baos1.toByteArray());
        DataInputStream dis1 = new DataInputStream(bais1);
        List<Student> stus1 = readStudents(dis1);
        System.out.println("使用 DataInputStream 读取多个 Student 对象：" + stus1);

        // 使用 Scanner 读取多个 Student 对象
        ByteArrayInputStream bais2 = new ByteArrayInputStream(baos2.toByteArray());
        Scanner scanner2 = new Scanner(new InputStreamReader(bais2));
        List<Student> stus2 = readStudents(scanner2);
        System.out.println("使用 Scanner 读取多个 Student 对象：" + stus2);

        // 使用 ObjectInputStream 读取多个 Student 对象
        ByteArrayInputStream bais3 = new ByteArrayInputStream(baos3.toByteArray());
        ObjectInputStream ois3 = new ObjectInputStream(bais3);
        List<Student> stus3 = readStudents(ois3);
        System.out.println("使用 ObjectInputStream 读取多个 Student 对象：" + stus3);
    }
}