Java浅拷贝与深拷贝（思维导图）

图1 拷贝思维导图（点击查看图片）

1，拷贝

　　有两个相同属性的对象A和B，A拥有初始化值，将其值拷贝到B中，使得B拥有与A“相同”数据的属性！注意这里的相同我有加双引号！

　　相同可能表示这么几个意思：①数值相同【指向不同的内存空间】；②地址相同【指向相同的内存空间】；

　　下面是直接使用"="进行复制的操作

 package com.cnblogs.mufasa.Demo1;

 import java.util.Date;

 class Person{//
     private int age=0;
     private Birth birth=new Birth();
     private String name="";

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

     public int getAge() {
         return age;
     }

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

     public Birth getBirth() {
         return birth;
     }

     public void setBirth(Birth birth) {
         this.birth = birth;
     }

     public String getName() {
         return name;
     }

     public void setName(String name) {
         this.name = name;
     }
     public String toString(){
         return "姓名："+name+",年龄："+age+",出生日期："+birth.toString();
     }
 }

 class Birth{//生日
     private String date="";
     public Birth(){}
     public Birth(String date){
         this.date=date;
     }

     public String getDate() {
         return date;
     }

     public void setDate(String date) {
         this.date = date;
     }

     @Override
     public String toString() {
         return this.date;
     }
 }

 public class Demo1 {//浅拷贝
     public static void main(String[] args) {
         Person p1=new Person(18,new Birth("19950729"),"万雨");
         Person p2=p1;
         System.out.println(p1.toString());
         System.out.println(p2.toString());

         p1.setAge(17);
         p1.setBirth(new Birth("2018"));
         p1.setName("Mufasa");

         System.out.println(p1.toString());
         System.out.println(p2.toString());

     }
 }

姓名：万雨,年龄：18,出生日期：19950729
姓名：万雨,年龄：18,出生日期：19950729
姓名：Mufasa,年龄：17,出生日期：2018
姓名：Mufasa,年龄：17,出生日期：2018

　　其实就相当于对原始对象进行操作

2，浅拷贝

　　Perosn类型对象有两个属性Age、name，将p1浅复制给p2

　　基本类型直接进行数值复制，引用类型进行地址拷贝（String类型比较特殊，属于引用类型，但是它存在一个常量池需要进行特殊对待）

图2 浅拷贝

使用构造方法进行浅拷贝：

 package com.cnblogs.mufasa.Demo;

 import java.util.Date;

 class Person{//
     private Age age;
     private String name;
     private int birth;
     public Person(Age age, String name,int birth) {
         this.age = age;
         this.name = name;
         this.birth = birth;
     }

     public Person(Person p1){
         this.age=p1.age;
         this.name=p1.name;
         this.birth=p1.birth;
     }

     public int getAge() {
         return this.age.getAge();
     }

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

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

     public int getBirth() {
         return birth;
     }

     public void setBirth(int birth) {
         this.birth = birth;
     }

     public String getName() {
         return this.name;
     }

     public void setName(String name) {
         this.name = name;
     }
     public String toString(){
         return "姓名："+this.name+",年龄："+this.age+",出生日期："+this.birth;
     }
 }

 class Age{
     private int age;
     public Age(){}
     public Age(int age){
         this.age=age;
     }

     public int getAge() {
         return age;
     }

     public void setAge(int age) {
         this.age = age;
     }
     public String toString(){
         return this.age+"";
     }
 }

 public class Demo {//浅拷贝-构造方法实现
     public static void main(String[] args) {
         Person p1=new Person(new Age(18),"万雨",1995);
         Person p2=new Person(p1);
         System.out.println(p1.toString());
         System.out.println(p2.toString());

         p1.setAge(17);
         p1.setBirth(2019);
         p1.setName("Mufasa");

         System.out.println(p1.toString());
         System.out.println(p2.toString());

     }
 }

使用继承Cloneable接口调用clone方法进行浅拷贝

 package com.cnblogs.mufasa.Demo2;

 import java.util.Date;

 class Person implements Cloneable{//
     private Age age;
     private String name;
     private int birth;
     public Person(Age age, String name,int birth) {
         this.age = age;
         this.name = name;
         this.birth = birth;
     }

     public Person clone(){
         Person obj=null;
         try {
             obj=(Person) super.clone();
         }catch (CloneNotSupportedException e){
             e.printStackTrace();
         }
 //        obj.age=(Age) this.getAge().clone();
         return obj;
     }

     public Age getAge() {
         return this.age;
     }

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

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

     public int getBirth() {
         return birth;
     }

     public void setBirth(int birth) {
         this.birth = birth;
     }

     public String getName() {
         return this.name;
     }

     public void setName(String name) {
         this.name = name;
     }
     public String toString(){
         return "姓名："+this.name+",年龄："+this.age+",出生日期："+this.birth;
     }
 }

 class Age implements Cloneable{
     private int age;
     public Age(){}
     public Age(int age){
         this.age=age;
     }
 //    public Age clone(){
 //        Age obj=null;
 //        try {
 //            obj=(Age) super.clone();
 //        }catch (CloneNotSupportedException e){
 //            e.printStackTrace();
 //        }
 //        return obj;
 //    }

     public int getAge() {
         return age;
     }

     public void setAge(int age) {
         this.age = age;
     }
     public String toString(){
         return this.age+"";
     }
 }

 public class Demo2 {//浅拷贝-继承Cloneable接口实现
     public static void main(String[] args) {
         Person p1=new Person(new Age(18),"万雨",1995);
         Person p2=(Person)p1.clone();
         System.out.println(p1.toString());
         System.out.println(p2.toString());

         p1.setAge(17);
         p1.setBirth(2019);
         p1.setName("Mufasa");

         System.out.println(p1.toString());
         System.out.println(p2.toString());

     }
 }

姓名：万雨,年龄：18,出生日期：1995
姓名：万雨,年龄：18,出生日期：1995
姓名：Mufasa,年龄：17,出生日期：2019
姓名：万雨,年龄：17,出生日期：1995

3，深拷贝

　　引用类型数据也进行新内存开辟与幅值，

图3 深拷贝

使用继承Cloneable接口调用clone方法进行深拷贝【每个引用对象都需要使用clone方法进行拷贝】

 package com.cnblogs.mufasa.Demo2;

 import java.util.Date;

 class Person implements Cloneable{//
     private Age age;
     private String name;
     private int birth;
     public Person(Age age, String name,int birth) {
         this.age = age;
         this.name = name;
         this.birth = birth;
     }

     public Person clone(){
         Person obj=null;
         try {
             obj=(Person) super.clone();
         }catch (CloneNotSupportedException e){
             e.printStackTrace();
         }
         obj.age=(Age) this.getAge().clone();
         return obj;
     }

     public Age getAge() {
         return this.age;
     }

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

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

     public int getBirth() {
         return birth;
     }

     public void setBirth(int birth) {
         this.birth = birth;
     }

     public String getName() {
         return this.name;
     }

     public void setName(String name) {
         this.name = name;
     }
     public String toString(){
         return "姓名："+this.name+",年龄："+this.age+",出生日期："+this.birth;
     }
 }

 class Age implements Cloneable{
     private int age;
     public Age(){}
     public Age(int age){
         this.age=age;
     }
     public Age clone(){
         Age obj=null;
         try {
             obj=(Age) super.clone();
         }catch (CloneNotSupportedException e){
             e.printStackTrace();
         }
         return obj;
     }

     public int getAge() {
         return age;
     }

     public void setAge(int age) {
         this.age = age;
     }
     public String toString(){
         return this.age+"";
     }
 }

 public class Demo2 {//浅拷贝-继承Cloneable接口实现
     public static void main(String[] args) {
         Person p1=new Person(new Age(18),"万雨",1995);
         Person p2=(Person)p1.clone();
         System.out.println(p1.toString());
         System.out.println(p2.toString());

         p1.setAge(17);
         p1.setBirth(2019);
         p1.setName("Mufasa");

         System.out.println(p1.toString());
         System.out.println(p2.toString());

     }
 }

使用继承Serializable接口进行序列化与反序列化进行深拷贝【注意对象不能使用transient进行修饰，原因：transient修饰的对象无法进行序列化！】

 package com.cnblogs.mufasa.Demo3;

 import java.io.*;

 class Person implements Serializable{
     private Age age;
     private String name;
     private int birth;
     public Person(Age age, String name,int birth) {
         this.age = age;
         this.name = name;
         this.birth = birth;
     }

     public Age getAge() {
         return this.age;
     }

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

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

     public int getBirth() {
         return birth;
     }

     public void setBirth(int birth) {
         this.birth = birth;
     }

     public String getName() {
         return this.name;
     }

     public void setName(String name) {
         this.name = name;
     }
     public String toString(){
         return "姓名："+this.name+",年龄："+this.age+",出生日期："+this.birth;
     }
 }

 class Age implements Serializable {
     private int age;
     public Age(){}
     public Age(int age){
         this.age=age;
     }
     public int getAge() {
         return age;
     }

     public void setAge(int age) {
         this.age = age;
     }
     public String toString(){
         return this.age+"";
     }
 }

 public class Demo3 {//浅拷贝-继承Cloneable接口实现
     public static void main(String[] args) throws IOException, ClassNotFoundException {
         Person p1=new Person(new Age(18),"万雨",1995);

         ByteArrayOutputStream bos=new ByteArrayOutputStream();
         ObjectOutputStream oos=new ObjectOutputStream(bos);

         oos.writeObject(p1);//1，先进行序列化
         oos.flush();
         ObjectInputStream ois=new ObjectInputStream(new ByteArrayInputStream(bos.toByteArray()));
         Person p2=(Person)ois.readObject();//2，进行反序列化

         System.out.println(p1.toString());
         System.out.println(p2.toString());

         p1.setAge(17);
         p1.setBirth(2019);
         p1.setName("Mufasa");

         System.out.println(p1.toString());
         System.out.println(p2.toString());

     }
 }

姓名：万雨,年龄：18,出生日期：1995
姓名：万雨,年龄：18,出生日期：1995
姓名：Mufasa,年龄：17,出生日期：2019
姓名：万雨,年龄：18,出生日期：1995