原型模式必知必会

文章目录

• ​​类图​​
• ​​实例​​
• ​​深克隆​​
• ​​深克隆破坏单例解决方式​​
• ​​个人理解​​
• ​​原型克隆和new的区别​​
• ​​原型模式和抽象工厂模式的区别​​
• ​​本质​​
• ​​代码地址:​​

类图

实例

public interface Prototype{
    Prototype clone();
}

public class ConcretePrototypeA implements Prototype {

    private int age;
    private String name;
    private List hobbies;

    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 List getHobbies() {
        return hobbies;
    }

    public void setHobbies(List hobbies) {
        this.hobbies = hobbies;
    }

    @Override
    public ConcretePrototypeA clone() {
        ConcretePrototypeA concretePrototype = new ConcretePrototypeA();
        concretePrototype.setAge(this.age);
        concretePrototype.setName(this.name);
        concretePrototype.setHobbies(this.hobbies);
        return concretePrototype;
    }

}

public class ConcretePrototypeB implements Prototype {

    @Override
    public Prototype clone() {
        return null;
    }
}

public class Client {

    private Prototype prototype;

    public Client(Prototype prototype){
        this.prototype = prototype;
    }
    public Prototype startClone(Prototype concretePrototype){
        return (Prototype)concretePrototype.clone();
    }

}

public class PrototypeTest {

    public static void main(String[] args) {

        // 创建一个具体的需要克隆的对象
        ConcretePrototypeA concretePrototype = new ConcretePrototypeA();
        // 填充属性，方便测试
        concretePrototype.setAge(18);
        concretePrototype.setName("prototype");
        List hobbies = new ArrayList<String>();
        concretePrototype.setHobbies(hobbies);
        System.out.println(concretePrototype);

        // 创建Client对象，准备开始克隆
        Client client = new Client(concretePrototype);
        ConcretePrototypeA concretePrototypeClone = (ConcretePrototypeA) client.startClone(concretePrototype);
        System.out.println(concretePrototypeClone);

        System.out.println("克隆对象中的引用类型地址值：" + concretePrototypeClone.getHobbies());
        System.out.println("原对象中的引用类型地址值：" + concretePrototype.getHobbies());
        System.out.println("对象地址比较："+(concretePrototypeClone.getHobbies() == concretePrototype.getHobbies()));


    }
}

深克隆

例子:

public class Monkey {
    public int height;
    public int weight;
    public Date birthday;
}

public class JinGuBang implements Serializable {
    public float h = 100;
    public float d = 10;

    public void big(){
        this.d *= 2;
        this.h *= 2;
    }

    public void small(){
        this.d /= 2;
        this.h /= 2;
    }
}

public class QiTianDaSheng extends Monkey implements Cloneable,Serializable {

    public JinGuBang jinGuBang;

    public  QiTianDaSheng(){
        //只是初始化
        this.birthday = new Date();
        this.jinGuBang = new JinGuBang();
    }

    @Override
    protected Object clone() throws CloneNotSupportedException {
        return this.deepClone();
    }


    //深克隆
    public Object deepClone(){
        try{

            ByteArrayOutputStream bos = new ByteArrayOutputStream();
            ObjectOutputStream oos = new ObjectOutputStream(bos);
            oos.writeObject(this);

            ByteArrayInputStream bis = new ByteArrayInputStream(bos.toByteArray());
            ObjectInputStream ois = new ObjectInputStream(bis);

            QiTianDaSheng copy = (QiTianDaSheng)ois.readObject();
            copy.birthday = new Date();
            return copy;

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

    }


    public QiTianDaSheng shallowClone(QiTianDaSheng target){

        QiTianDaSheng qiTianDaSheng = new QiTianDaSheng();
        qiTianDaSheng.height = target.height;
        qiTianDaSheng.weight = target.height;

        qiTianDaSheng.jinGuBang = target.jinGuBang;
        qiTianDaSheng.birthday = new Date();
        return  qiTianDaSheng;
    }

    //浅克隆
    public QiTianDaSheng deep2(QiTianDaSheng target){

        QiTianDaSheng qiTianDaSheng = new QiTianDaSheng();
        qiTianDaSheng.height = target.height;
        qiTianDaSheng.weight = target.height;

        qiTianDaSheng.jinGuBang =  target.jinGuBang;
        qiTianDaSheng.birthday = new Date();
        return  qiTianDaSheng;
    }

}

public class DeepCloneTest {

    public static void main(String[] args) {

        QiTianDaSheng qiTianDaSheng = new QiTianDaSheng();
        try {
            QiTianDaSheng clone = (QiTianDaSheng)qiTianDaSheng.clone();
            System.out.println("深克隆：" + (qiTianDaSheng.jinGuBang == clone.jinGuBang));
        } catch (Exception e) {
            e.printStackTrace();
        }

        QiTianDaSheng q = new QiTianDaSheng();
        QiTianDaSheng n = q.shallowClone(q);
        System.out.println("浅克隆：" + (q.jinGuBang == n.jinGuBang));


    }
}

深克隆破坏单例解决方式

要么你我们的单例类不实现Cloneable接口；
要么我们重写clone()方法，在clone方法中返回单例对象即可，具体代码如下：

@Override
protected Object clone() throws CloneNotSupportedException{
  return INSTANCE;
}

Cloneable源码分析先看我们常用的ArrayList就实现了Cloneable接口，来看代码clone()方法的实现：`

public Object clone(){
  try{
    ArrayList<?>v=(ArrayList<?>)
    super.clone();v.elementData=Arrays.copyOf(elementData,size);
       v.modCount=0;
       return v;
  }catch(CloneNotSupportedExceptione){
    。。。
  }

个人理解

感觉和之前new出来一个对象，再set值一样，只是，这个set的功能在对象内部。对外只暴露一个clone或者其他自定义接口。

原型克隆和new的区别

原型模式和抽象工厂模式的区别

本质

​​本质: 克隆生成对象。​​

代码地址:

​​https://github.com/hufanglei/pattern-learn/tree/master/src/main/java/com/example/prototype​​​

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