原型模式用于克隆复杂对象，由于new一个实例对象会消耗大部分时间，所以原型模式可以节约大量时间

 1 public class Sheep implements Cloneable{
 2     private String name;
 3     private Date birth;
 4     public Sheep(String name, Date birth) {
 5         this.name = name;
 6         this.birth = birth;
 7     }
 8     @Override
 9     protected Object clone(){
10         Sheep obj = null;
11         try {
12             obj = (Sheep) super.clone();
13             //深复制
14 //            obj.birth = (Date) this.birth.clone();
15         } catch (CloneNotSupportedException e) {
16             e.printStackTrace();
17         }
18         return obj;
19     }
20     public String getName() {
21         return name;
22     }
23     public void setName(String name) {
24         this.name = name;
25     }
26     public Date getBirth() {
27         return birth;
28     }
29     public void setBirth(Date birth) {
30         this.birth = birth;
31     }
32     
33 }

import java.util.Date;

public class Client {
    public static void main(String[] args) {
        Date date = new Date(1515529952L);
        Sheep s1 = new Sheep("s1",date);
        Sheep s2 = (Sheep) s1.clone();
        System.out.println(s1.getBirth());
        System.out.println(s2.getBirth());
        date.setTime(15L);//修改后
        System.out.println(s1.getBirth());
        System.out.println(s2.getBirth());
    }
}

 1 浅复制
 2     Sun Jan 18 20:58:49 CST 1970
 3     Sun Jan 18 20:58:49 CST 1970
 4     //修改后
 5     Thu Jan 01 08:00:00 CST 1970
 6     Thu Jan 01 08:00:00 CST 1970
 7 深复制
 8     Sun Jan 18 20:58:49 CST 1970
 9     Sun Jan 18 20:58:49 CST 1970
10     修改后
11     Thu Jan 01 08:00:00 CST 1970  //只对s1修改
12     Sun Jan 18 20:58:49 CST 1970