JAVA几种方式实现深拷贝

准备

定义两个类用于测试拷贝，类内容如下，目的是深拷贝一个User类的对象：

@Data@Accessors(chain = true)public class User {    private Integer id;    private Integer age;    private String name;    private Car car;    private String category;}

@Data@Accessors(chain = true)public class Car {    private Integer id;    private String color;    private String name;} 

实现

package com.demo;import com.fasterxml.jackson.core.JsonProcessingException;import com.fasterxml.jackson.databind.ObjectMapper;import lombok.Data;import lombok.experimental.Accessors;import java.io.*;@Data@Accessors(chain = true)public class User implements Cloneable, Serializable {    private Integer id;    private Integer age;    private String name;    private Car car;    private String category;    @Override    public User clone() throws CloneNotSupportedException {        return (User) super.clone();    }        public User copyUser1() {        User copyUser = new User()                .setId(this.getId())                .setName(this.getName())                .setAge(this.getAge())                .setCategory(this.getCategory());        if (this.getCar() != null) {            copyUser.setCar(new Car().setId(this.getCar().getId())                    .setColor(this.getCar().getColor())                    .setName(this.getCar().getName()));        }        return copyUser;    }        public User copyUser2() throws CloneNotSupportedException {        User cloneUser = this.clone();        if(this.getCar() != null) {            cloneUser.setCar(this.getCar().clone());        }        return cloneUser;    }        public User copyUser3() throws IOException, ClassNotFoundException {        ByteArrayOutputStream bos = new ByteArrayOutputStream();        ObjectOutputStream oos = new ObjectOutputStream(bos);        oos.writeObject(this);        ByteArrayInputStream bis = new ByteArrayInputStream(bos.toByteArray());        ObjectInputStream ois = new ObjectInputStream(bis);        return (User) ois.readObject();    }        public User copyUser4() throws JsonProcessingException {        ObjectMapper objectMapper = new ObjectMapper();        return objectMapper.readValue(objectMapper.writeValueAsString(this),User.class);    }} 

验证

package com.demo;import java.io.IOException;public class CopyDemo {    public static void main(String[] args) throws IOException, CloneNotSupportedException, ClassNotFoundException {        User user = new User().setAge(10).setName("李四").setId(3).setCategory("工人");        user.setCar(new Car().setName("保时捷").setId(999).setColor("黑色"));        User copyUser1 = user.copyUser1();        System.out.println("copyUser1:" + copyUser1);        System.out.println("copyUser1与user对象是否是同一个:" + (System.identityHashCode(user) == System.identityHashCode(copyUser1)));        System.out.println("copyUser1中的car与user中的car是否是同一个:"+(System.identityHashCode(user.getCar()) == System.identityHashCode(copyUser1.getCar())));        System.out.println("====================");        User copyUser2 = user.copyUser2();        System.out.println("copyUser2:" + copyUser2);        System.out.println("copyUser2与user对象是否是同一个:" + (System.identityHashCode(user) == System.identityHashCode(copyUser2)));        System.out.println("copyUser2中的car与user中的car是否是同一个:"+(System.identityHashCode(user.getCar()) == System.identityHashCode(copyUser2.getCar())));        System.out.println("====================");        User copyUser3 = user.copyUser3();        System.out.println("copyUser3:" + copyUser3);        System.out.println("copyUser3与user对象是否是同一个:" + (System.identityHashCode(user) == System.identityHashCode(copyUser3)));        System.out.println("copyUser3中的car与user中的car是否是同一个:"+(System.identityHashCode(user.getCar()) == System.identityHashCode(copyUser3.getCar())));        System.out.println("====================");        User copyUser4 = user.copyUser4();        System.out.println("copyUser4:" + copyUser4);        System.out.println("copyUser4与user对象是否是同一个:" + (System.identityHashCode(user) == System.identityHashCode(copyUser4)));        System.out.println("copyUser4中的car与user中的car是否是同一个:"+(System.identityHashCode(user.getCar()) == System.identityHashCode(copyUser4.getCar())));    }}

验证结果

copyUser1:User(id=3, age=10, name=李四, car=Car(id=999, color=黑色, name=保时捷), category=工人)copyUser1与user对象是否是同一个:falsecopyUser1中的car与user中的car是否是同一个:false====================copyUser2:User(id=3, age=10, name=李四, car=Car(id=999, color=黑色, name=保时捷), category=工人)copyUser2与user对象是否是同一个:falsecopyUser2中的car与user中的car是否是同一个:false====================copyUser3:User(id=3, age=10, name=李四, car=Car(id=999, color=黑色, name=保时捷), category=工人)copyUser3与user对象是否是同一个:falsecopyUser3中的car与user中的car是否是同一个:false====================copyUser4:User(id=3, age=10, name=李四, car=Car(id=999, color=黑色, name=保时捷), category=工人)copyUser4与user对象是否是同一个:falsecopyUser4中的car与user中的car是否是同一个:false

结论

使用java原生推荐方法三，方法一、方法二缺点过于明显，第三方库的方式可以用方法四，spring boot默认的序列化反序列化就是Jackson，另外比照方法四同类的类库也能实现

来源地址：https://blog.csdn.net/qq_43842093/article/details/132137006