Java-序列化—（三）序列化实现深拷贝

浅拷贝是指拷贝对象时仅仅拷贝对象本身（包括对象中的基本变量），而不拷贝对象包含的引用指向的对象。深拷贝不仅拷贝对象本身，而且拷贝对象包含的引用指向的所有对象。举例来说更加清楚：对象A1中包含对B1的引用，B1中包含对C1的引用。浅拷贝A1得到A2，A2 中依然包含对B1的引用，B1中依然包含对C1的引用。深拷贝则是对浅拷贝的递归，深拷贝A1得到A2，A2中包含对B2（B1的copy）的引用，B2 中包含对C2（C1的copy）的引用。

package Clone;

import java.io.Serializable;
import java.util.HashMap;
import java.util.Map;

/**
 * @ClassName: CopyDemo
 * @Author sandy.n.hao
 * @Date: 2019-07-10
 * @Version v1.0.0
 * @Description: //TODO
 */

public class CopyDemo {

    public static void main(String[] args) {

        Person p1 = new Person("Sandy",18);
        Person p2 = new Person("Monica",20);

        Map map1= new HashMap();
        Map temp= new HashMap();

        map1.put("first",p1);

        temp.put("temp","temp");

        Map map2 = new HashMap();
        Map map3 = new HashMap();

        System.out.println("拷贝前：");
        System.out.println("map1: "+map1);
        System.out.println("map2: "+map2);
        System.out.println("map3: "+map3);


        /*
         * 浅拷贝
         */
        map2.putAll(map1);

        /*
         * 深拷贝
         */
        map3 = Utils.DeepClone(map1);


        //拷贝后
        System.out.println("拷贝结果：");
        System.out.println("map1: "+map1);
        System.out.println("map2: "+map2);
        System.out.println("map3: "+map3);

//        ((Map)(map1.get("first"))).put("final","final");
        ((Person)(map1.get("first"))).setName("Coco");
        ((Person)(map1.get("first"))).setAge(20);

        System.out.println("修改后：");
        System.out.println("map1: "+map1);
        System.out.println("map2: "+map2);
        System.out.println("map3: "+map3);
    }

    /*
    内部类实现序列化
     */
    public static class Person implements Serializable
    {
        private static final long serialVersionUID = 8656128222714547171L;
        transient private String name;
        private int age;

        Person(String name,int age){
            this.name= name;
            this.age=age;
        }

        public int getAge() {
            return age;
        }

        public String getName() {
            return name;
        }

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

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

        @Override
        public String toString() {
            return "Person{" +
                    "name='" + name + '\'' +
                    ", age=" + age +
                    '}';
        }
    }

}

package com.sandy.DeepAndShallowCopy;

import com.sun.xml.internal.messaging.saaj.util.ByteInputStream;

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


public class Utils {

    public static  T DeepClone (Object obj){
        T cloneObj = null;
        try{
            ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
            ObjectOutputStream objectOutputStream = new ObjectOutputStream(byteArrayOutputStream);
            objectOutputStream.writeObject(obj);
            objectOutputStream.close();

            ByteInputStream byteInputStream = new ByteInputStream(byteArrayOutputStream.toByteArray(),byteArrayOutputStream.size());
            ObjectInputStream objectInputStream = new ObjectInputStream(byteInputStream);
            cloneObj = (T) objectInputStream.readObject();
            objectInputStream.close();


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

输出：

拷贝前：
map1: {first=Person{name='Sandy', age=18}}
map2: {}
map3: {}
拷贝结果：
map1: {first=Person{name='Sandy', age=18}}
map2: {first=Person{name='Sandy', age=18}}
map3: {first=Person{name='null', age=18}}
修改后：
map1: {first=Person{name='Coco', age=20}}
map2: {first=Person{name='Coco', age=20}}
map3: {first=Person{name='null', age=18}}

map3通过序列化的方式实现了深拷贝，name用transient，未进行序列化，是实现深拷贝。