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。

下面是实现该任务的代码：

Product类：

import java.io.Serializable;

public class Product implements Serializable {
    private int id;
    private String name;
    private String categories;
    private double price;

    public Product(int id, String name, 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 String getCategories() {
        return categories;
    }

    public double getPrice() {
        return price;
    }
}

Test类：

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", "Mobile phone", 7999.0);
        Product ipad = new Product(2, "iPad", "Tablet", 4999.0);
        Product macbook = new Product(3, "MacBook", "Laptop", 12999.0);
        Product iwatch = new Product(4, "iWatch", "Smart watch", 2599.0);

        try {
            // 实例化对象输出流
            ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream("products.dat"));

            // 写入对象
            oos.writeObject(iphone);
            oos.writeObject(ipad);
            oos.writeObject(macbook);
            oos.writeObject(iwatch);

            // 关闭对象输出流
            oos.close();

            // 实例化对象输入流
            ObjectInputStream ois = new ObjectInputStream(new FileInputStream("products.dat"));

            // 从文件里读取对象并输出到控制台上
            for (int i = 0; i < 4; i++) {
                Product product = (Product) ois.readObject();
                System.out.println("ID: " + product.getId());
                System.out.println("Name: " + product.getName());
                System.out.println("Categories: " + product.getCategories());
                System.out.println("Price: " + product.getPrice());
                System.out.println();
            }

            // 关闭对象输入流
            ois.close();
        } catch (IOException | ClassNotFoundException e) {
            e.printStackTrace();
        }
    }
}

运行Test类，输出结果如下：

ID: 1
Name: iPhone
Categories: Mobile phone
Price: 7999.0

ID: 2
Name: iPad
Categories: Tablet
Price: 4999.0

ID: 3
Name: MacBook
Categories: Laptop
Price: 12999.0

ID: 4
Name: iWatch
Categories: Smart watch
Price: 2599.0