java 软硬拷贝

淡淡的烟草味﹌ 2022-12-09 02:49 69阅读 0赞

1. 软拷贝就是复制对象的值；一般是java.lang.Object 类里面的clone() 方法；  
2. 硬拷贝是复制这个对象所有的东西，如果该对象引用了其他对象，则引用也会改变到复制的新对象那边。  
一般硬拷贝是使用序列化，然后再反析出来；（把对象写到流里面的过程叫序列化过程，从流中读取对象的过程叫反序列化过程）  
transient 修饰的不能序列化，也就不能硬拷贝。

代码：

首先是软拷贝的例子：

public class CloneTest1 \{

public static void main(String\[\] args) throws CloneNotSupportedException \{  
Student student1 = new Student();  
student1.setName("ZhangSan");  
student1.setAge(20);

Student student2 = new Student();  
**student2 = (Student) student1.clone();**

System.out.println("拷贝得到的信息");  
System.out.println(student2.getName());  
System.out.println(student2.getAge());  
System.out.println("-------------");

// 修改第二个对象的信息  
student2.setName("LiSi");  
student2.setAge(25);

System.out.println("修改第二个对象的属性为lisi,25后：");  
System.out.println("第一个对象：");  
System.out.println(student1.getName());  
System.out.println(student1.getAge());  
System.out.println("第二个对象：");  
System.out.println(student2.getName());  
System.out.println(student2.getAge());  
System.out.println("-------------");

// 说明两个引用student1和student2指向的是不同的对象

\}  
\}

class Student implements Cloneable \{

private String name;  
private int age;

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;  
\}

@Override  
public Object clone() throws CloneNotSupportedException \{  
// 注意此处要把protected改为public

Object object = super.clone();

return object;  
\}  
\}

结果截图：  
![68da416f0787cf57ef78dbf1b51896ba.png][]

硬拷贝栗子：  
代码：

import java.io.ByteArrayInputStream;  
import java.io.ByteArrayOutputStream;  
import java.io.ObjectInputStream;  
import java.io.ObjectOutputStream;  
import java.io.Serializable;

public class CloneTest3 \{

public static void main(String\[\] args) throws Exception \{  
Teacher3 t = new Teacher3();  
t.setName("Teacher Wang");  
t.setAge(50);

Student3 s1 = new Student3();  
s1.setAge(20);  
s1.setName("ZhangSan");  
s1.setTeacher(t);

**Student3 s2 = (Student3) s1.deepClone();**

System.out.println("拷贝得到的信息:");  
System.out.println(s2.getName());  
System.out.println(s2.getAge());  
System.out.println(s2.getTeacher().getName());  
System.out.println(s2.getTeacher().getAge());  
System.out.println("---------------------------");

// 将复制后的对象的老师信息修改一下：  
s2.getTeacher().setName("New Teacher Wang");  
s2.getTeacher().setAge(28);

System.out.println("修改了拷贝对象的教师后：");  
System.out.println("拷贝对象的教师：");  
System.out.println(s2.getTeacher().getName());  
System.out.println(s2.getTeacher().getAge());  
System.out.println("原来对象的教师：");  
System.out.println(s1.getTeacher().getName());  
System.out.println(s1.getTeacher().getAge());

// 由此证明序列化的方式实现了对象的深拷贝

class Teacher3 implements Serializable \{

private String name;  
private int age;

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;  
\}

class Student3 implements Serializable \{

private String name;  
private int age;  
private Teacher3 teacher;

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 Teacher3 getTeacher() \{  
return teacher;  
\}

public void setTeacher(Teacher3 teacher) \{  
this.teacher = teacher;  
\}

**public Object deepClone() throws Exception \{**

**// 序列化  
ByteArrayOutputStream bos = new ByteArrayOutputStream();  
ObjectOutputStream oos = new ObjectOutputStream(bos);**

**oos.writeObject(this);**

**// 反序列化  
ByteArrayInputStream bis = new ByteArrayInputStream(bos.toByteArray());  
ObjectInputStream ois = new ObjectInputStream(bis);**

**return ois.readObject();  
\}**

截图：

![57e15f8fc6ecea2f7a5ec73089ffff26.png][]

[68da416f0787cf57ef78dbf1b51896ba.png]: /images/20221123/e780aef80a234f899770ef1fa19fac25.png
[57e15f8fc6ecea2f7a5ec73089ffff26.png]: /images/20221123/24118ad1a34a40de9c613507b5ffb5d4.png