Serialization

☕ Person.java

//  ⭐️ 직렬화되려면 Serializable 구현
public class Person implements Serializable {

    //  💡 serialVersionUID : 클래스의 버전 번호로 사용
    private static final long serialVersionUID = 1L;
    private String name;
    //private String fullName;
    private int age;
    private double height;
    private boolean married;

    //  💡 transient : 직렬화에서 제외
    transient private String bloodType;
    transient private double weight;

    //  ⭐️ 직렬화에 포함되려면 해당 클래스도 Serializable 구현
    private Career career;

    public Person(
            String name, int age, double height, boolean married,
            String bloodType, double weight, Career career
    ) {
        this.name = name;
        //this.fullName = name;
        this.age = age;
        this.height = height;
        this.married = married;
        this.bloodType = bloodType;
        this.weight = weight;
        this.career = career;
    }
}

☕ Career.java

public class Career implements Serializable {
    private static final long serialVersionUID = 1L;
    private String company;
    private int years;

    public Career(String company, int years) {
        this.company = company;
        this.years = years;
    }
}

☕ Ex01.java

		public static String PEOPLE_PATH = "src/sec12/chap05/people.ser";

				Person person1 = new Person(
                "홍길동", 20, 175.5, false,
                "AB", 81.2,
                new Career("ABC Market", 2)
        );
        Person person2 = new Person(
                "전우치", 35, 180.3, true,
                "O", 74.3,
                new Career("Macrosoft", 14)
        );

        List<Person> people = new ArrayList<>();
        people.add(person1);
        people.add(person2);
        people.add(new Person(
                "임꺽정", 45, 162.8, true,
                "A", 68.3,
                new Career("Koryeo Inc.", 20)
        ));
        people.add(new Person(
                "붉은매", 24, 185.3, false,
                "B", 79.3,
                new Career("Cocoa", 30)
        ));

				//  💡 ObjectOutputStream : 직렬화 구현한 인스턴스를 스트림으로 출력
        try (
                FileOutputStream fos = new FileOutputStream(PEOPLE_PATH);
                BufferedOutputStream bos = new BufferedOutputStream(fos);
                ObjectOutputStream oos = new ObjectOutputStream(bos);
        ) {
            oos.writeObject(person1);
            oos.writeObject(person2);
            oos.writeObject(people);
        } catch (IOException e) {
            throw new RuntimeException(e);
        }

☕ Ex02.java

				Person person1Out;
        Person person2Out;
        List<Person> peopleOut;

        //  ⭐️ 다시 인스턴스로 역직렬화
        try (
                FileInputStream fis = new FileInputStream(PEOPLE_PATH);
                BufferedInputStream bis = new BufferedInputStream(fis);
                ObjectInputStream ois = new ObjectInputStream(bis);
        ) {

            //  ⚠️ 직렬화할 때와 순서 동일해야 함
            //  - 순서 바꾸고 재실행 해 볼 것
            person1Out = (Person) ois.readObject();
            person2Out = (Person) ois.readObject();
            peopleOut = (ArrayList) ois.readObject();

        } catch (IOException | ClassNotFoundException e) {
            throw new RuntimeException(e);
        }

        System.out.println(person1Out);
        System.out.println(person2Out);
        System.out.println(peopleOut);

<aside> 💡 serialVersionUID : 직렬화하여 주고받을 클래스의 버전

</aside>