3：原型模式

问题 ：现有一只羊 tom ，age =1 ，color = white 编写程序创建和tom养属性完全相同的10只羊

原型模式：用原型实例指定创建对象的种类，并且通过拷贝原型，创建新的对象

传统方法

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);
        //...
    }

clone

Object 有一个clone方法

public static void main(String[] args) {
        System.out.println("原型模式完成对象的创建");
        // TODO Auto-generated method stub
        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());
    }

implements Cloneable 重写clone方法

public class Sheep implements Cloneable {
    private String name;
    private int age;
    private String color;
    private String address = "蒙古羊";
    public Sheep friend; //是对象, 克隆是会如何处理
    public Sheep(String name, int age, String color) {
        super();
        this.name = name;
        this.age = age;
        this.color = color;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public int getAge() {
        return age;
    }
    public void setAge(int age) {
        this.age = age;
    }
    public String getColor() {
        return color;
    }
    public void setColor(String color) {
        this.color = color;
    }
    @Override
    public String toString() {
        return "Sheep [name=" + name + ", age=" + age + ", color=" + color + ", address=" + address + "]";
    }
    //克隆该实例，使用默认的clone方法来完成
    @Override
    protected Object clone()  {
        Sheep sheep = null;
        try {
            sheep = (Sheep)super.clone();
        } catch (Exception e) {
            // TODO: handle exception
            System.out.println(e.getMessage());
        }
        // TODO Auto-generated method stub
        return sheep;
    }
}

源码使用 spring beanxml scope = “prototype”

浅拷贝

克隆对象里面的对象 直接指向原本的地址

深拷贝

重写clone

对象序列化

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
    @Override
    protected 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;
        deepProtoType.deepCloneableTarget  = (DeepCloneableTarget)deepCloneableTarget.clone();
        // TODO Auto-generated method stub
        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) {
            // TODO: handle exception
            e.printStackTrace();
            return null;
        } finally {
            //关闭流
            try {
                bos.close();
                oos.close();
                bis.close();
                ois.close();
            } catch (Exception e2) {
                // TODO: handle exception
                System.out.println(e2.getMessage());
            }
        }
    }
}

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

原型模式注意事项