Java设计模式之java原型模式详解

目录

• 介绍
• 角色
• Java语言提供的clone()方法
• 代码演示―克隆羊
  • 结论
• 深浅拷贝
  • 深浅拷贝探讨
  • 实现深克隆的方式一 ： 手动对引用对象进行克隆
  • 实现深克隆的方式一 ：序列化
• 原型模式对单例模式的破坏
• 优缺点
• 适用场景
• 原型模式在Spring中的应用场景
• 总结

//实现Cloneable接口
@Data
public class Sheep implements Cloneable
{
    private String name;
    private Integer age;
    //重写Object的clone方法
    @Override
    protected Object clone() throws CloneNotSupportedException 
    {
        Sheep sheep=null;
        sheep=(Sheep)super.clone();
        return sheep;
    }
}

        //创建原型对象
        Sheep sheep=new Sheep();
        sheep.setAge(3);
        sheep.setName("肖恩");
        //克隆
        Sheep sheep1 = sheep.clone();
        Sheep sheep2=sheep.clone();
        System.out.println(sheep1);
        System.out.println(sheep2);
        System.out.println(sheep1==sheep2);

protected native Object clone() throws CloneNotSupportedException;

@Data
@AllArgsConstructor
@NoArgsConstructor
public class Pig 
{
    String name;
    Integer age;
}

//实现Cloneable接口
@Data
public class Sheep implements Cloneable
{
    private String name;
    private Integer age;
    private  Pig pig;
    //重写Object的clone方法
    @Override
    protected Sheep clone() throws CloneNotSupportedException
    {
        Sheep sheep=null;
        sheep=(Sheep)super.clone();
        return sheep;
    }
}

public class test
{
    @Test
    public void test() throws CloneNotSupportedException {
        //创建原型对象
        Sheep sheep=new Sheep();
        sheep.setAge(3);
        sheep.setName("肖恩");
        sheep.setPig(new Pig("大忽悠",3));
        //克隆
        Sheep sheep1 = sheep.clone();
        Sheep sheep2=sheep.clone();
        System.out.println(sheep1);
        System.out.println(sheep2);
        System.out.println(sheep1==sheep2);
        System.out.println("==============================");
        System.out.println(sheep1.getPig()==sheep2.getPig());
    }
}

@Data
@AllArgsConstructor
@NoArgsConstructor
public class Pig implements Cloneable
{
    String name;
    Integer age;
    @Override
    protected Object clone() throws CloneNotSupportedException {
        return super.clone();
    }
}

//实现Cloneable接口
@Data
public class Sheep implements Cloneable
{
    private String name;
    private Integer age;
    private  Pig pig;
    //重写Object的clone方法
    @Override
    protected Sheep clone() throws CloneNotSupportedException
    {
        Sheep sheep=null;
        sheep=(Sheep)super.clone();
        sheep.pig=(Pig)sheep.pig.clone();
        return sheep;
    }
}

@Data
@AllArgsConstructor
@NoArgsConstructor
public class Pig implements Serializable
{
    String name;
    Integer age;
}

//实现Cloneable接口
@Data
public class Sheep implements Serializable
{
    private String name;
    private Integer age;
    private  Pig pig;
 //序列化方式完成深拷贝
    public Sheep deepClone() throws IOException, ClassNotFoundException {
        //先将要序列化的对象写入流中
        ByteArrayOutputStream baot=new ByteArrayOutputStream();
        //ObjectOutputStream构造函数的参数是，将对象流写入到哪里
        ObjectOutputStream oot=new ObjectOutputStream(baot);
          oot.writeObject(this);
          //将序列化的对象从流中读取出来
        ByteArrayInputStream bait=new ByteArrayInputStream(baot.toByteArray());
        ObjectInputStream oit=new ObjectInputStream(bait);
        return (Sheep) oit.readObject();
    }
}

public class HungrySingleton implements Serializable, Cloneable {
    private final static HungrySingleton hungrySingleton;
    static {
        hungrySingleton = new HungrySingleton();
    }
    private HungrySingleton() 
    {}
    public static HungrySingleton getInstance() {
        return hungrySingleton;
    }
    private Object readResolve() {
        return hungrySingleton;
    }
    @Override
    protected Object clone() throws CloneNotSupportedException {
        return super.clone();
    }
}

public class Test {
    public static void main(String[] args) throws CloneNotSupportedException, NoSuchMethodException, InvocationTargetException, IllegalAccessException {
        HungrySingleton hungrySingleton = HungrySingleton.getInstance();
        Method method = hungrySingleton.getClass().getDeclaredMethod("clone");
        method.setAccessible(true);
        HungrySingleton cloneHungrySingleton = (HungrySingleton) method.invoke(hungrySingleton);
        System.out.println(hungrySingleton);
        System.out.println(cloneHungrySingleton);
    }
}

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