浅谈浅克隆（shallow clone）和 深克隆（deep clone）

区别就在于是否对对象中的引用变量所指向的对象进行拷贝。

1.浅克隆/浅复制/浅拷贝

　　浅拷贝是指在拷贝对象时，对于基本数据类型的变量会重新复制一份，而对于引用类型的变量只是对引用进行拷贝，没有对引用指向的对象进行拷贝。

2.深克隆/深复制/深拷贝

　　深拷贝是指在拷贝对象时，同时会对引用指向的对象进行拷贝。

示例代码：

 import java.util.Date;

 class Wife implements Cloneable {
     private String name;
     private Date birthday;

     public Wife(){
     }

     public Wife(String name, Date birthday) {
         this.name = name;
         this.birthday = birthday;
     }

     public Date getBirthday(){
         return birthday;
     }

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

     public Object clone() throws CloneNotSupportedException {
         return super.clone();
     }

     public String toString() {
         return "Wife [name=" + name + ", birthday=" + birthday + "]";
     }

 }

 class Husband implements Cloneable {
     private String name;
     private Wife wife;

     public Husband(){
     }

     public Husband(String name, Wife wife) {
         this.name = name;
         this.wife = wife;
     }

     public Wife getWife() {
         return wife;
     }

     public void setWife(Wife wife) {
         this.wife = wife;
     }

     public String getName() {
         return name;
     }

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

     /**
      * 浅克隆一个对象
      * @throws CloneNotSupportedException
      */
     public Object shallowClone() throws CloneNotSupportedException {
         return super.clone();
     }
     /**
      * 利用串行化深克隆一个对象，把对象以及它的引用读到流里，在写入其他的对象
      * @return
      * @throws Exception
      */
     public Object deepClone() throws Exception {
         Husband husband = (Husband) super.clone();
         husband.wife = (Wife) this.wife.clone();
         return husband;
     }
 }

 public class Test {
     public static void main(String[] args) throws Exception{
         //浅克隆
         Wife w1 = new Wife("曹夫人", new Date());
         Husband h1 = new Husband("曹先生", w1);
         Husband h2 = (Husband) h1.shallowClone();

         System.out.println("原型对象：" + h1.getName() + "--" + h1.getWife());
         System.out.println("克隆对象：" + h2.getName() + "--" + h2.getWife());

         w1.setName("张夫人");

         System.out.println("\n--------------------------修改克隆对象的属性值后---------------------------\n");

         System.out.println("原型对象：" + h1.getName() + "--" + h1.getWife());
         System.out.println("克隆对象：" + h2.getName() + "--" + h2.getWife());

         System.out.println("\n---------------------------------------------------------------------\n");

         //深克隆
         Wife w2 = new Wife("曹夫人", new Date());
         Husband h3 = new Husband("曹先生", w2);
         Husband h4 = (Husband) h3.deepClone();

         System.out.println("原型对象：" + h3.getName() + "--" + h3.getWife());
         System.out.println("克隆对象：" + h4.getName() + "--" + h4.getWife());

         w2.setName("张夫人");

         System.out.println("\n--------------------------修改克隆对象的属性值后---------------------------\n");

         System.out.println("原型对象：" + h3.getName() + "--" + h3.getWife());
         System.out.println("克隆对象：" + h4.getName() + "--" + h4.getWife());

     }
 }

控制台输出：

原型对象：曹先生--Wife [name=曹夫人, birthday=Mon Jan 15 18:00:35 CST 2018]
克隆对象：曹先生--Wife [name=曹夫人, birthday=Mon Jan 15 18:00:35 CST 2018]

--------------------------修改克隆对象的属性值后---------------------------

原型对象：曹先生--Wife [name=张夫人, birthday=Mon Jan 15 18:00:35 CST 2018]
克隆对象：曹先生--Wife [name=张夫人, birthday=Mon Jan 15 18:00:35 CST 2018]

---------------------------------------------------------------------

原型对象：曹先生--Wife [name=曹夫人, birthday=Mon Jan 15 18:00:35 CST 2018]
克隆对象：曹先生--Wife [name=曹夫人, birthday=Mon Jan 15 18:00:35 CST 2018]

--------------------------修改克隆对象的属性值后---------------------------

原型对象：曹先生--Wife [name=张夫人, birthday=Mon Jan 15 18:00:35 CST 2018]
克隆对象：曹先生--Wife [name=曹夫人, birthday=Mon Jan 15 18:00:35 CST 2018]