23种设计模式详讲-原型模式

一、什么是原型模式：
传统的创建的对象，可以用new直接新建对象，但是如果某些类的属性太多，这样构造起来会相对复杂；这里提供了一种不用通过构造方法，创建对象的方法；通过Jdk自带的Cloneable接口，实现对象的拷贝，创建新的对象；

二、何时使用原型模式：

原型模式其实就是一个对象在创建另一个可定制的对象，而且不需要指定任何创建的细节。Java提供了Cloneable接口，其中有一个唯一方法Clone()，实现这个接口就可以完成原型模式了。
一般在初始化的信息不发生变化的情况下，克隆是最好的办法。既隐藏了对象创建的细节，又对性能是大大的提高。不用重新初始化对象，而是动态地获得对象运行时的状态。

三、原型模式大概分为潜拷贝和深度拷贝：

1）潜拷贝：

代码示例：

package com.jason.study.design.prototype.simple;

import com.jason.study.design.prototype.Teacher;

public class School  implements   Cloneable {
    private  String name;
    private  int id;
    private Teacher teacher;

    public String getName() {
        return name;
    }

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

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public Teacher getTeacher() {
        return teacher;
    }

    public void setTeacher(Teacher teacher) {
        this.teacher = teacher;
    }

    @Override
    protected Object clone() throws CloneNotSupportedException {

        return super.clone();
    }
}

package com.jason.study.design.prototype.simple;

import com.jason.study.design.prototype.Teacher;

public class TestSimpleCopy {
    public static void main(String[] args) {
           School  school=new School();
           school.setId(1);
           school.setName("红小");
           Teacher teacher=new Teacher();
           teacher.setName("zhang lao shi");
           school.setTeacher(teacher);
           System.out.println("school"+school);
           System.out.println("school.getTeacher()"+teacher);
           School  school1=null;
           try{
               school1= (School) school.clone();
               System.out.println("school1"+school1);
               System.out.println("school1.getTeacher()"+school1.getTeacher());
               school1.getTeacher().setName("wanglaoshi");
               System.out.println("school.getTeacher().getName()="+school.getTeacher().getName());
               System.out.println("school1.getTeacher().getName()="+school1.getTeacher().getName());

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

    }
}

运行结果：

2）深度拷贝：

代码示例：

package com.jason.study.design.prototype.deep;

import com.jason.study.design.prototype.Teacher;

import java.io.*;

public class School  implements   Cloneable ,Serializable{
    private  String name;
    private  int id;
    private Teacher teacher;

    public String getName() {
        return name;
    }

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

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public Teacher getTeacher() {
        return teacher;
    }

    public void setTeacher(Teacher teacher) {
        this.teacher = teacher;
    }

    @Override
    protected Object clone() throws CloneNotSupportedException {
        School school=(School)super.clone();
        School s1=null;
        try
        {
            //先将实例串行化到文件
            FileOutputStream fos = new FileOutputStream("sersingleton.txt");
            ObjectOutputStream oos=new ObjectOutputStream(fos);
            oos.writeObject(school);
            oos.flush();
            oos.close();
            fos.close();

            //从文件读出原有的单例类
            FileInputStream fis =new FileInputStream("Sersingleton.txt");
            ObjectInputStream ois=new ObjectInputStream(fis);
            s1=(School)ois.readObject();
            ois.close();
            fis.close();
            System.out.println(s1==school);
        } catch (Exception e) {
            e.printStackTrace();
        }

        return s1;
    }
}
package com.jason.study.design.prototype.deep;

import com.jason.study.design.prototype.Teacher;
import com.jason.study.design.prototype.deep.School;

public class TestDeepCopy {
    public static void main(String[] args) {
       School school=new School();
        school.setId(1);
        school.setName("红小");
        Teacher teacher=new Teacher();
        teacher.setName("zhang lao shi");
        school.setTeacher(teacher);
        System.out.println("school"+school);
        System.out.println("school.getTeacher()"+teacher);
        School school1=null;
        try{
            school1= (School) school.clone();
            System.out.println("school1"+school1);
            System.out.println("school1.getTeacher()"+school1.getTeacher());
            school1.getTeacher().setName("wanglaoshi");
            System.out.println("school.getTeacher().getName()="+school.getTeacher().getName());
            System.out.println("school1.getTeacher().getName()="+school1.getTeacher().getName());

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

运行结果：

通过序列化的方式，完成了深度拷贝，school中Teacher引用也重新创建了对象；