java中的浅拷贝与深拷贝

java中的浅拷贝与深拷贝

浅拷贝

实现方法：要拷贝的类，实现Cloneable接口，而后重写clone方法，便可实现浅拷贝。

但缺点在于，若是该类的成员包含其余类，则其余类并无被拷贝，只是拷贝了一个引用对象，其指向的地址和以前的对象一致，所以，修改people1的宠物信息，people的宠物信息也变了。

package cn.flycold.深浅拷贝.浅拷贝;

import lombok.AllArgsConstructor;
import lombok.Builder;
import lombok.Data;
import lombok.NoArgsConstructor;

/** * @author liyutong03 * @description * @date 2019/10/30 * Copyright (C) 2015 Meituan * All rights reserved */
public class 浅拷贝 { 
    public static void main(String []args) throws CloneNotSupportedException{ 
        Pet pet = Pet.builder().pAge(2).pName("包子").build();
        People people = People.builder().age(23).name("lyt").pet(pet).build();
        People people1 = people.clone();
        System.out.println("people :" + people);
        System.out.println("people1:" + people1);
        people1.setName("zzz");
        people1.setAge(19);
        people1.getPet().setPName("馒头");
        people1.getPet().setPAge(3);
        System.out.println("after change people1");
        System.out.println("people :" + people);
        System.out.println("people1:" + people1);
    }
}

@Data
@Builder
@NoArgsConstructor
@AllArgsConstructor
class People implements Cloneable{ 
    private int age;
    private String name;
    private Pet pet;

    @Override
    public People clone() throws CloneNotSupportedException{ 
        return (People) super.clone();
    }
}

@Data
@Builder
@NoArgsConstructor
@AllArgsConstructor
class Pet{ 
    private String pName;
    private int pAge;
}

深拷贝

咱们能够用两种方法实现深拷贝

实现Cloneable接口

对要拷贝的类，以及其引用的类，都实现Cloneable接口，并重写clone方法。

注意，包含其余类的类，须要注意clone方法的实现，须要手动调用包含的类的clone方法

这种方法的劣势在于，层级太多的话代码会很麻烦。

实现Serializable接口

Serializable接口是用来序列化和反序列化的，咱们用输出流将员对象序列化为字节，在用输入流将字节反序列化为对象，就实现了深拷贝，好处是简单，咱们只需在类上标注其实现 Seriablizeable接口，注意，包含的类也要标注,便可。

package cn.flycold.深浅拷贝.深拷贝;

import lombok.AllArgsConstructor;
import lombok.Builder;
import lombok.Data;
import lombok.NoArgsConstructor;

import java.io.*;

/** * @author liyutong03 * @description * @date 2019/10/30 * Copyright (C) 2015 Meituan * All rights reserved */
public class 深拷贝 { 
    public static void main(String []args) throws Exception{ 
        Pet pet = Pet.builder().pAge(2).pName("包子").build();
        People people = People.builder().age(23).name("lyt").pet(pet).build();
        // Cloneable实现深拷贝
        // People people1 = people.clone();

        // Serializable实现深拷贝
        People people1 = (People) deepCopy(people);
        System.out.println("people :" + people);
        System.out.println("people1:" + people1);
        people1.setName("zzz");
        people1.setAge(19);
        people1.getPet().setPName("馒头");
        people1.getPet().setPAge(3);
        System.out.println("after change people1");
        System.out.println("people :" + people);
        System.out.println("people1:" + people1);
    }

    public static Object deepCopy(Object object) throws Exception { 
        ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
        ObjectOutputStream oos = new ObjectOutputStream(byteArrayOutputStream);
        oos.writeObject(object);

        ObjectInputStream ois = new ObjectInputStream(new ByteArrayInputStream(byteArrayOutputStream.toByteArray()));
        return ois.readObject();


    }
}



@Data
@Builder
@NoArgsConstructor
@AllArgsConstructor
class People implements Cloneable, Serializable { 
    private int age;
    private String name;
    private Pet pet;

    @Override
    public People clone() throws CloneNotSupportedException{ 
        People people =  (People) super.clone();
        people.setPet(people.getPet().clone());
        return people;
    }
}

@Data
@Builder
@NoArgsConstructor
@AllArgsConstructor
class Pet implements Cloneable, Serializable{ 
    private String pName;
    private int pAge;

    @Override
    public Pet clone() throws CloneNotSupportedException{ 
        return (Pet)super.clone();
    }
}