物件的深拷貝一般有三種：

1、在構造方法階段深拷貝：對每個屬性建立相同的字面量

2、實現Cloneable介面，告訴JVM這是一個可以拷貝的類，並重寫Object.clone()方法，實現對引用物件深度遍歷拷貝

3、就是通過序列化和反序列化的方式

import java.io.Serializable;


public class Address implements Serializable {
    String address;

    public Address(String address) {
        this.address = address;
    }

    
 
public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }
}

import java.io.*;

public class User implements Serializable {
    String name;
    Address address;

    public User(String name, Address address) {
        
 
this.name = name;
        this.address = address;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Address getAddress() {
        return address;
    }

    public void setAddress(Address address) {
        
 
this.address = address;
    }

    // 實際的資料流向：ObjectOutputStream->ByteArrayOutputStream->ByteArrayInputStream ->ObjectInputStream，深度複製從序列化物件又轉為序列化物件
    public User copy() throws IOException, ClassNotFoundException {
        // 序列化
        ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
        ObjectOutputStream objectOutputStream = new ObjectOutputStream(byteArrayOutputStream);
        objectOutputStream.writeObject(this);   // 將this物件 轉變為 二進位制位元組流

        // 反序列化
        ByteArrayInputStream byteArrayInputStream = new ByteArrayInputStream(byteArrayOutputStream.toByteArray());
        ObjectInputStream objectInputStream = new ObjectInputStream(byteArrayInputStream);
        return (User) objectInputStream.readObject();
    }
}

import java.io.IOException;

public class TestDeepCopy {
    public static void main(String[] args) throws IOException, ClassNotFoundException {
        User u1 = new User("Liu Haoran", new Address("Henan Province"));
        User u2 = u1.copy();
        System.out.println(u1 == u2);   // u1和u2在Java堆中的地址不同
        // 但是二者的屬性的字面量是相同的
        System.out.println("u1:" + u1.getName() + " " + u1.getAddress().getAddress());
        System.out.println("u2:" + u2.getName() + " " + u2.getAddress().getAddress());
    }
}