前言

一、克隆羊问题

sheep类

package tanchishell.SJMS.prototype;import java.util.Objects;public class Sheep {private int age;private String name;private String color;public Sheep() {}public Sheep( String name,int age, String color) {this.age = age;this.name = name;this.color = color;}@Overridepublic String toString() {return "Sheep{" +"age=" + age +", name='" + name + '\\'' +", color='" + color + '\\'' +'}';}@Overridepublic boolean equals(Object o) {if (this == o) return true;if (o == null || getClass() != o.getClass()) return false;Sheep sheep = (Sheep) o;return age == sheep.age && Objects.equals(name, sheep.name) && Objects.equals(color, sheep.color);}@Overridepublic int hashCode() {return Objects.hash(age, name, color);}public int getAge() {return age;}public void setAge(int age) {this.age = age;}public String getName() {return name;}public void setName(String name) {this.name = name;}public String getColor() {return color;}public void setColor(String color) {this.color = color;}
}

clint 调用方

package tanchishell.SJMS.prototype;public class Client {public static void main(String[] args) {
// TODO Auto-generated method stub
//传统的方法Sheep sheep = new Sheep("tom", 1, "白色");Sheep sheep2 = new Sheep(sheep.getName(), sheep.getAge(), sheep.getColor());Sheep sheep3 = new Sheep(sheep.getName(), sheep.getAge(), sheep.getColor());Sheep sheep4 = new Sheep(sheep.getName(), sheep.getAge(), sheep.getColor());Sheep sheep5 = new Sheep(sheep.getName(), sheep.getAge(), sheep.getColor());
//.... System.out.println(sheep);System.out.println(sheep2);System.out.println(sheep3);System.out.println(sheep4);System.out.println(sheep5);
//... }}
}输出Sheep{age=1, name='tom', color='白色'}
Sheep{age=1, name='tom', color='白色'}
Sheep{age=1, name='tom', color='白色'}
Sheep{age=1, name='tom', color='白色'}

二、引入原型模式动态克隆对象

sheep类

package tanchishell.SJMS.prototype;import java.util.Objects;public class Sheep implements Cloneable {private int age;private String name;private String color;private String address = "蒙古羊";public Sheep friend; //是对象, 克隆是会如何处理, 默认是浅拷贝public Sheep() {}//克隆该实例，使用默认的 clone 方法来完成@Overrideprotected Object clone() {Sheep sheep = null;try {sheep = (Sheep) super.clone();} catch (Exception e) {System.out.println(e.getMessage());}return sheep;}public Sheep(String name, int age, String color) {this.age = age;this.name = name;this.color = color;}@Overridepublic String toString() {return "Sheep{" +"age=" + age +", name='" + name + '\\'' +", color='" + color + '\\'' +", address='" + address + '\\'' +", friend=" + friend +'}';}@Overridepublic boolean equals(Object o) {if (this == o) return true;if (o == null || getClass() != o.getClass()) return false;Sheep sheep = (Sheep) o;return age == sheep.age && Objects.equals(name, sheep.name) && Objects.equals(color, sheep.color);}@Overridepublic int hashCode() {return Objects.hash(age, name, color);}public int getAge() {return age;}public void setAge(int age) {this.age = age;}public String getName() {return name;}public void setName(String name) {this.name = name;}public String getColor() {return color;}public void setColor(String color) {this.color = color;}
}

clint 类

package tanchishell.SJMS.prototype;public class Client {public static void main(String[] args) {System.out.println("原型模式完成对象的创建");Sheep sheep = new Sheep("tom", 1, "白色");sheep.friend = new Sheep("jack", 2, "黑色");Sheep sheep2 = (Sheep)sheep.clone(); //克隆Sheep sheep3 = (Sheep)sheep.clone(); //克隆Sheep sheep4 = (Sheep)sheep.clone(); //克隆Sheep sheep5 = (Sheep)sheep.clone(); //克隆System.out.println("sheep2 =" + sheep2 + "sheep2.friend=" + sheep2.friend.hashCode());System.out.println("sheep3 =" + sheep3 + "sheep3.friend=" + sheep3.friend.hashCode());System.out.println("sheep4 =" + sheep4 + "sheep4.friend=" + sheep4.friend.hashCode());System.out.println("sheep5 =" + sheep5 + "sheep5.friend=" + sheep5.friend.hashCode());System.out.println(sheep == sheep2);}
}输出
原型模式完成对象的创建
sheep2 =Sheep{age=1, name='tom', color='白色', address='蒙古羊', friend=Sheep{age=2, name='jack', color='黑色', address='蒙古羊', friend=null}}sheep2.friend=102206883
sheep3 =Sheep{age=1, name='tom', color='白色', address='蒙古羊', friend=Sheep{age=2, name='jack', color='黑色', address='蒙古羊', friend=null}}sheep3.friend=102206883
sheep4 =Sheep{age=1, name='tom', color='白色', address='蒙古羊', friend=Sheep{age=2, name='jack', color='黑色', address='蒙古羊', friend=null}}sheep4.friend=102206883
sheep5 =Sheep{age=1, name='tom', color='白色', address='蒙古羊', friend=Sheep{age=2, name='jack', color='黑色', address='蒙古羊', friend=null}}sheep5.friend=102206883false

三、原型模式在Spring框架中源码分析

在使用 xml 配置 bean 时，可以选择参数 scope = ”prototype“ 来确定使用 原型模式还是单例模式，会调用到 dogetBean 方法，先判断参数是否需要使用单例模式，如果不成立会去判断 是否需要使用原型模式 else if ( mbd . isPrototype) 进行原型模式的业务逻辑

先进入 applictionContext 的 getBean 方法

进入 getBean 会先进入 assertBeanFactoryActive（）方法，然后进入getBeanFactory( )，里面是同步代码块同步获取Bean工厂，从getBeanFactory( ) 方法出来后进入 getBean( ) 方法，就会尝试在工厂里面获取一个 bean 对象，genBean 会调用到 doget Bean（）方法

会先判断是否为 单例模式，是不是需要创建单例对象

然后 else if 判断是否需要配置原型模式，条件成立后，会调用到 creatBean（）方法返回一个原型实例

四、深拷贝与浅拷贝

从上面的输出结果我们就可以看出，克隆羊的时候，它的朋友是没有被克隆的，所以是浅拷贝，如果想要达到深拷贝的效果，可以通过实现 克隆接口和序列化接口来实现

完整代码

DeepCloneableTarget

package tanchishell.SJMS.prototype;import java.io.Serializable;
import java.util.Objects;public class DeepCloneableTarget implements Serializable, Cloneable {private static final long serialVersionUID = 1L;private String cloneName;private String cloneClass;//构造器public DeepCloneableTarget(String cloneName, String cloneClass) {this.cloneName = cloneName;this.cloneClass = cloneClass;}//因为该类的属性，都是 String , 因此我们这里使用默认的 clone 完成即可@Overrideprotected Object clone() throws CloneNotSupportedException {return super.clone();}
}

DeepProtoType

package tanchishell.SJMS.prototype;import java.io.*;
import java.util.Objects;public class DeepProtoType implements Serializable, Cloneable{public String name; //String 属性public DeepCloneableTarget deepCloneableTarget;// 引用类型public DeepProtoType() {super();}//深拷贝 - 方式 1 使用 clone 方法@Overrideprotected Object clone() throws CloneNotSupportedException {Object deep = null;//这里完成对基本数据类型(属性)和 String 的克隆deep = super.clone();//对引用类型的属性，进行单独处理DeepProtoType deepProtoType = (DeepProtoType) deep;Object clone = deepCloneableTarget.clone();deepProtoType.deepCloneableTarget = (DeepCloneableTarget) deepCloneableTarget.clone();//通过强制类型转换创建了新的对象，改变了内存地址System.out.println(deepProtoType.deepCloneableTarget.hashCode() +" =====  "+ clone.hashCode());return deepProtoType;}//深拷贝 - 方式 2 通过对象的序列化实现 (推荐)public Object deepClone() {//创建流对象ByteArrayOutputStream bos = null;ObjectOutputStream oos = null;ByteArrayInputStream bis = null;ObjectInputStream ois = null;try {//序列化bos = new ByteArrayOutputStream();oos = new ObjectOutputStream(bos);oos.writeObject(this); //当前这个对象以对象流的方式输出//反序列化bis = new ByteArrayInputStream(bos.toByteArray());ois = new ObjectInputStream(bis);DeepProtoType copyObj = (DeepProtoType) ois.readObject();return copyObj;} catch (Exception e) {e.printStackTrace();return null;} finally {//关闭流try {bos.close();oos.close();bis.close();ois.close();} catch (Exception e2) {System.out.println(e2.getMessage());}}}
}

Client2

package tanchishell.SJMS.prototype;public class Client2 {public static void main(String[] args) throws Exception {// TODO Auto-generated method stubDeepProtoType p = new DeepProtoType();p.name = "宋江";p.deepCloneableTarget = new DeepCloneableTarget("大牛", "小牛");//方式 1 完成深拷贝
//        DeepProtoType p2 = (DeepProtoType) p.clone();
//        DeepProtoType p3 = (DeepProtoType) p.clone();
//        DeepProtoType p4 = (DeepProtoType) p.clone();
//
//        System.out.println("p.name=" + p.name + "p.deepCloneableTarget=" + p.deepCloneableTarget.hashCode());
//        System.out.println("p2.name=" + p2.name + "p2.deepCloneableTarget=" + p2.deepCloneableTarget.hashCode());
//        System.out.println("p3.name=" + p3.name + "p3.deepCloneableTarget=" + p3.deepCloneableTarget.hashCode());
//        System.out.println("p4.name=" + p4.name + "p3.deepCloneableTarget=" + p4.deepCloneableTarget.hashCode());//方式 2 完成深拷贝DeepProtoType p2 = (DeepProtoType) p.deepClone();System.out.println("p.name=" + p.name + "p.deepCloneableTarget=" + p.deepCloneableTarget.hashCode());System.out.println("p2.name=" + p.name + "p2.deepCloneableTarget=" + p2.deepCloneableTarget.hashCode());}
}

五、原型模式的注意事项和细节