Java对象拷贝

public class Person implements Serializable {
    private String name;
    private int age;
    private GregorianCalendar birthday;
    public Person(){
       
    }
    public Person(String name, int age, GregorianCalendar birthday){
        this.name = name;
        this.age = age;
        this.birthday = birthday;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public int getAge() {
        return age;
    }
    public void setAge(int age) {
        this.age = age;
    }
    public GregorianCalendar getBirthday() {
        return birthday;
    }
    public void setBirthday(GregorianCalendar birthday) {
        this.birthday = birthday;
    }
    public static  void main(String[] args) {
        Person p = new Person("张三",13,new GregorianCalendar(1985,8,1));
        Person p2 = null;
        try{
            ByteArrayOutputStream byteOut = new ByteArrayOutputStream();
            ObjectOutputStream oos = new ObjectOutputStream(byteOut);
            oos.writeObject(p);