使用序列化的方式完全克隆对象

小咪咪 2022-05-14 06:15 129阅读 0赞

对象深度克隆一般有两种方式

## 1.实现 Cloneable 接口并重写 Object 类中的 clone()方法； ##

如果类中包含一个类，那么两个类都要实现clone()方法。

## 2.实现 Serializable 接口，通过对象的序列化和反序列化实现克隆，可以实现真正的深度克隆，代码如下。 ##

1.Test

package com.nightliar.bootdemo;
    
    import java.io.*;
    
    /** * Created by Nightliar * 2018-08-21 9:58 */
    public class Test { 
    
        @org.junit.Test
        public void mains() throws Exception {
            User user1 = new User();
            user1.setId(12);
            user1.setName("zhangsan");
            Cat cat = new Cat();
            cat.setCatName("baoma");
            cat.setId(343L);
            user1.setCat(cat);
            System.out.println("原user1:" + user1);
    
            User user2 = Test.clone(user1);
            System.out.println("原user2:" + user2);
    
            user2.setName("lisi");
            user2.setId(2);
            Cat cat2 = new Cat();
            cat2.setCatName("benci");
            cat2.setId(999L);
            user2.setCat(cat2);
            System.out.println("新user2:" + user2);
            System.out.println("原user1:" + user1);
    
        }
    
        @SuppressWarnings("unchecked")
        public static <T extends Serializable> T clone(T obj) throws Exception {
            ByteArrayOutputStream bout = new ByteArrayOutputStream();
            ObjectOutputStream oos = new ObjectOutputStream(bout);
            oos.writeObject(obj);
            ByteArrayInputStream bin = new ByteArrayInputStream(bout.toByteArray());
            ObjectInputStream ois = new ObjectInputStream(bin);
            return (T) ois.readObject();
            // 说明：调用 ByteArrayInputStream 或 ByteArrayOutputStream 对象的 close 方法没有任何意义
            // 这两个基于内存的流只要垃圾回收器清理对象就能够释放资源，这一点不同于对外部资源（如文件流）的释放
        }
    
    }

结果：
    原user1:User{
       id=12, cat=Cat{
       id=343, catName='baoma'}, name='zhangsan'}
    原user2:User{
       id=12, cat=Cat{
       id=343, catName='baoma'}, name='zhangsan'}
    新user2:User{
       id=2, cat=Cat{
       id=999, catName='benci'}, name='lisi'}
    原user1:User{
       id=12, cat=Cat{
       id=343, catName='baoma'}, name='zhangsan'}

2.User

package com.nightliar.bootdemo;
    
    import java.io.Serializable;
    
    /** * Created by Nightliar * 2018-09-04 8:50 */
    public class User implements Serializable { 
        private int id;
        private Cat cat;
        private String name;
    
        public int getId() {
            return id;
        }
    
        public void setId(int id) {
            this.id = id;
        }
    
        public Cat getCat() {
            return cat;
        }
    
        public void setCat(Cat cat) {
            this.cat = cat;
        }
    
        public String getName() {
            return name;
        }
    
        public void setName(String name) {
            this.name = name;
        }
    
        @Override
        public String toString() {
            return "User{" + "id=" + id + ", cat=" + cat + ", name='" + name + '\'' + '}';
        }
    }

3.Cat

package com.nightliar.bootdemo;
    
    import java.io.Serializable;
    
    /** * Created by Nightliar * 2018-09-04 8:51 */
    public class Cat implements Serializable { 
        private Long id;
        private String catName;
    
        public Long getId() {
            return id;
        }
    
        public void setId(Long id) {
            this.id = id;
        }
    
        public String getCatName() {
            return catName;
        }
    
        public void setCatName(String catName) {
            this.catName = catName;
        }
    
        @Override
        public String toString() {
            return "Cat{" + "id=" + id + ", catName='" + catName + '\'' + '}';
        }
    }