在Java中使用XMLEncoder进行序列化

Question

After an hour of going through the wikis and conventions of using XMLEncoder in Java, I stil can't make any progress of serialising my SystemSnapshot class using XMLEncoder. Can anyone tell me what's going wrong? My resources are as follows :

package core;

import gui.SceneManager;
import java.io.Serializable;

/**
 *
 * @author Subhra
*/

public class SystemSnapshot implements Serializable{

private static final long serialVersionUID = -6637378268413872760L;

private final School school;

private final User[] users;

private final String colorName;

public SystemSnapshot(){
    school = SessionManager.getSchool();
    users = UserStore.getUsers();
    colorName = SceneManager.getColor();
}

public SystemSnapshot(School school, User[] users, String c) {
    this.school = school;
    this.users = users;
    this.colorName = c;
}

public School getSchool() {
    return school;
}

public User[] getUsers() {
    return users;
}

public String getColorName() {
    return colorName;
}

}

No errors in the terminal. But the output is like this :

<?xml version="1.0" encoding="UTF-8"?>
<java version="1.8.0_40" class="java.beans.XMLDecoder">
<object class="core.SystemSnapshot"/>
</java>

Anyone?

After jtahlborn's answer i figured out and added all getters and setters. Now i'm getting two types of outputs. Case 1 :

XMLEncoder xml = new XMLEncoder(new FileOutputStream("try.xml"));
School ss = new School("S");
ss.addSubject(new Subject("BEnals"));
ss.addTeacher(new Teacher("Nil","T0",21,5000,new Subject("S")));
ss.addClass(new Standard(1,1));
ss.addStudent("STU0");
User u = new User(UserType.ADMIN,"Subhra","subhra","itsveryconfidential");
SystemSnapshot ss2 = new SystemSnapshot(ss,new User[]{u},"A string");
xml.writeObject(ss2);
xml.close();

is producing the right output. Whereas Case 2 :

XMLEncoder oos = new XMLEncoder(new FileOutputStream("data.base"));
SystemSnapshot ss = new   SystemSnapshot(SessionManager.getSchool(),UserStore.getUsers(),SceneManager.getColor());
oos.writeObject(ss);
oos.close();

is still producing the output shown above. What to do?

Source Code for SessionManager and UserStore

SessionManager.java

package core;

import core.User.UserType;
public class SessionManager {

private static User currentuser;

private static School school;

public static void setSchool(School schol) {
     school = schol;
}

public static School getSchool() {
    return school;
}

public static User getCurrentuser() {
    return currentuser;
}

public static void setCurrentuser(User currentuser) {
    SessionManager.currentuser = currentuser;
}

public static UserType getCurrentUserType(){
    return currentuser.getType();
}

}

UserStore.java

package core;

public class UserStore {

private static User[] users = new User[0];

public static User[] getUsers() {
    return users;
}

public static void setUsers(User[] users) {
    UserStore.users = users;
}

public static void addUser(User u) {
    users = new BIO<User>().addToArray(users,u);
}

public static void removeUser(User u) {
    users = new BIO<User>().removeFromArray(users,u);
}

public static User getUser(String username){
    for(User u : users){
        if(u.getUsername().equals(username)){
            return u;
        }
    }
    return null;
}

}

What's wrong?

Answer 1

my guess is that your SystemSnapshot is not a valid java bean because it doesn't have setters for your properties. the XMLEncoder doesn't do the same magic that normal serialization does, it requires valid java beans (getters and setters for all properties).