객체 직렬화

• 객체 직렬화 

객체를 byte의 흐름으로 만들어서 전송(어딘가에 쓰겠다)

객체 직렬화가 되려면, 특별한 인터페이스가 필요 or 기본형이거나

> Serializable(마크 인터페이스 - 메소드가 없는 인터페이스)

객체를 통으로 저장하고, 통으로 불러오는 것이 용이

private transient String pw;

// transient 직렬화 할 때  제외 >> 객체 전송할 때 제외함

public class User implements Serializable{

       

       //User가 가지는 필드들의 Type도 직렬화가 되어야 한다

       private String name;

       private String id;

       private transient String pw; // transient 직렬화에 제외 >> 전송할 때 제외함

       private int age;

       

       public int getAge() {

             return age;

       }

       public void setAge(int age) {

             this.age = age;

       }

       public String getName() {

             return name;

       }

       public void setName(String name) {

             this.name = name;

       }

       public String getId() {

             return id;

       }

       public void setId(String id) {

             this.id = id;

       }

       public String getPw() {

             return pw;

       }

       public void setPw(String pw) {

             this.pw = pw;

       }

}

 

public class ObjectOutputTest {

       public static void main(String[] args) {

             

             ObjectOutputStream oos = null;

             

             try {

                    oos = new ObjectOutputStream(new FileOutputStream("object.dat"));

                    List<User> list = new ArrayList<User>();

                    

                    User user= new User();

                    user.setName("홍");

                    user.setId("Ho");

                    user.setPw("1234");

                    user.setAge(10);

                    list.add(user);

                    

                    User user2= new User();

                    user2.setName("길");

                    user2.setId("n");

                    user2.setPw("5678");

                    user2.setAge(20);

                    list.add(user2);

                    

                    User user3= new User();

                    user3.setName("동");

                    user3.setId("g");

                    user3.setPw("90");

                    user3.setAge(30);

                    list.add(user3);

                    

                    oos.writeObject(list);

                    

             }catch(Exception ex) {

                    ex.printStackTrace();

             }finally {

                    try {

                           oos.close();

                    }catch(Exception ex) {

                           ex.printStackTrace();

                    }

             }

       }

}

public class ObjectInputTest {

       public static void main(String[] args) {

             

             ObjectInputStream ois = null;

             

             try {

                    

                    File f = new File("object2.dat");

                    if(!f.exists()) {

                           System.out.println("object.dat 파일이 없습니다");

                        // System.exit(0) > 웹프로그래밍에서는 절대 사용 금지 > WAS가 꺼질 수 있음

                           return; // 메인 함수 종료

                    }

                    

                    ois = new ObjectInputStream(new FileInputStream(f));

                    //Object obj  = ois.readObject();

                    List<User> list = (ArrayList)ois.readObject();

                    

                    for(int i =0; i<list.size(); i++) {

                    

                           User user = list.get(i);

                    

                           System.out.println(user.getName());

                           System.out.println(user.getId());

                           System.out.println(user.getPw());

                           System.out.println(user.getAge());

                           System.out.println("------------------");

                    

                    }

             }catch(Exception ex) {

                    ex.printStackTrace();

             }finally {

                    try {

                           ois.close();

                    }catch(Exception ex) {}

             }

       }

}