Java中淺克隆和深克隆之異同

目錄

• 1 概述
• • 1.1 淺克隆
  • 1.2 深克隆
  • 1.3 異同點
• 2 案例
• • 2.1 淺克隆實作步驟
  • 2.2 深克隆實作步驟

1 概述

1.1 淺克隆

建立一個新對象，新對象的屬性值和原來對象完全相同，對于非基本類型屬性，仍指向原有屬性所指向的對象。

1.2 深克隆

建立一個新對象，屬性中引用的其他對象也會被克隆，不再指向原有對象。

1.3 異同點

1. 深淺克隆都會在堆中新建立一個對象；
2. 差別在于對象屬性引用的對象是否也進行了克隆（遞歸性的，深的克隆，淺的不克隆）；

示例

1. pos:目前對象的位址；
2. son:son屬性所指向的位址；
3. name:對象的name屬性。

2 案例

2.1 淺克隆實作步驟

1. 實作Cloneable接口（辨別接口，沒有任何接口方法，表明實作該接口的類可被克隆）；
2. 在類中重寫Object類中的clone()方法，調用super.clone()，實作淺克隆;
3. 把克隆的引用指向原型對象新的克隆體；

class Address{
    private Integer id;
    private String name;

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

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

import java.io.*;

class Person implements Cloneable,Serializable{
    private String name;
    private Integer age;
    private Address address;

    public String getName() {
        return name;
    }

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

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    public Address getAddress() {
        return address;
    }

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

    @Override
    public String toString() {
        return this.name+"  "+this.age+"  "+this.address+"  "+super.toString();
    }

    @Override
    protected Object clone() throws CloneNotSupportedException {
        Object o = null;
        try{
            o = (Person)super.clone();
        }catch (Exception e){
            e.printStackTrace();
        }
        return o;
    }
}
           

public class MyTest {
    public static void main(String[] args) throws Exception{
        Address address = new Address();
        address.setId(1);
        address.setName("西安");

        Person person1 = new Person();
        person1.setName("張三");
        person1.setAge(24);
        person1.setAddress(address);
        Person person2 = (Person)person1.clone();

        System.out.println(person1);
        System.out.println(person2);
    }
}
           

瓜田李下  24  Address@4554617c  Person@74a14482
瓜田李下  24  Address@4554617c  Person@1540e19d
           

2.2 深克隆實作步驟

1. 實作Cloneable和Serializable接口（該接口也為辨別接口，表明實作該接口的類可被序列化）；
2. 在類中重寫Object類中的clone()方法，通過對象的序列化和反序列化實作深克隆；
3. 把克隆的引用指向原型對象新的克隆體；

import java.io.Serializable;

class Address implements Serializable{
    private Integer id;
    private String name;

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

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

import java.io.*;

class Person implements Cloneable,Serializable{
    private String name;
    private Integer age;
    private Address address;

    public String getName() {
        return name;
    }

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

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    public Address getAddress() {
        return address;
    }

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

    @Override
    public String toString() {
        return this.name+"  "+this.age+"  "+this.address+"  "+super.toString();
    }

    @Override
    protected Object clone() throws CloneNotSupportedException {
        Object o = null;
        try{
            ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
            ObjectOutputStream objectOutputStream = new ObjectOutputStream(outputStream);
            objectOutputStream.writeObject(this);

            ByteArrayInputStream inputStream = new ByteArrayInputStream(outputStream.toByteArray());
            ObjectInputStream objectInputStream = new ObjectInputStream(inputStream);

            o = objectInputStream.readObject();

        }catch (Exception e){
            e.printStackTrace();
        }
        return o;
    }
}
           

public class MyTest {
    public static void main(String[] args) throws Exception{
        Address address = new Address();
        address.setId(1);
        address.setName("西安");

        Person person1 = new Person();
        person1.setName("張三");
        person1.setAge(24);
        person1.setAddress(address);
        Person person2 = (Person)person1.clone();

        System.out.println(person1);
        System.out.println(person2);
    }
}
           

張三  24  Address@330bedb4  Person@45ee12a7
張三  24  Address@66d3c617  Person@63947c6b