应用对象序列化和对象反序列化向文件写入对象，并将对象读取出来输入到控制台上。任务要求： 1、创建Product类，并声明它的属性：id，name,categories,price 2、实现Serializable接口； 3、定义Product类构造方法； 4、在Test类里面，创建Product类的对象：iphone,ipad,macbook,iwatch 5、实例化对象输入流和对象输出流； 6、写入Product类的四个对象； 7、从文件里读取四个product类的四个对象。

好的，以下是代码实现：

Product.java:

import java.io.Serializable;
import java.util.List;

public class Product implements Serializable {
    private static final long serialVersionUID = 1L;
    private int id;
    private String name;
    private List<String> categories;
    private double price;

    public Product(int id, String name, List<String> categories, double price) {
        this.id = id;
        this.name = name;
        this.categories = categories;
        this.price = price;
    }

    public int getId() {
        return id;
    }

    public String getName() {
        return name;
    }

    public List<String> getCategories() {
        return categories;
    }

    public double getPrice() {
        return price;
    }

    @Override
    public String toString() {
        return "Product{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", categories=" + categories +
                ", price=" + price +
                '}';
    }
}

Test.java:

import java.io.*;

public class Test {
    public static void main(String[] args) {
        // 创建Product类的四个对象
        Product iphone = new Product(1, "iPhone", List.of("手机", "电子产品"), 9999.99);
        Product ipad = new Product(2, "iPad", List.of("平板电脑", "电子产品"), 5999.99);
        Product macbook = new Product(3, "MacBook", List.of("笔记本电脑", "电子产品"), 12999.99);
        Product iwatch = new Product(4, "iWatch", List.of("手表", "智能穿戴"), 3999.99);

        // 实例化对象输入流和对象输出流
        ObjectOutputStream oos = null;
        ObjectInputStream ois = null;

        try {
            // 写入Product类的四个对象
            oos = new ObjectOutputStream(new FileOutputStream("products.dat"));
            oos.writeObject(iphone);
            oos.writeObject(ipad);
            oos.writeObject(macbook);
            oos.writeObject(iwatch);
            System.out.println("写入对象成功！");

            // 从文件里读取四个product类的四个对象
            ois = new ObjectInputStream(new FileInputStream("products.dat"));
            Product p1 = (Product) ois.readObject();
            Product p2 = (Product) ois.readObject();
            Product p3 = (Product) ois.readObject();
            Product p4 = (Product) ois.readObject();
            System.out.println("读取对象成功！");

            // 输出到控制台
            System.out.println(p1);
            System.out.println(p2);
            System.out.println(p3);
            System.out.println(p4);
        } catch (IOException | ClassNotFoundException e) {
            e.printStackTrace();
        } finally {
            // 关闭流
            try {
                if (oos != null) {
                    oos.close();
                }
                if (ois != null) {
                    ois.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}