1. 定义

原型实例指定创建对象的种类，并且通过拷贝这些原型创建新的对象。

2. 实现

2.1 Cloneable接口clone方法

2.1.1 Product

实现Cloneable接口clone方法，clone方法中编写深拷贝逻辑

class Product implements Cloneable {
    private String part1;
    private String part2;
    private String part3;
    private String part4;
    private Info info;
    public Product(String part1, String part2, String part3, String part4, Info info) {
        this.part1 = part1;
        this.part2 = part2;
        this.part3 = part3;
        this.part4 = part4;
        this.info = info;
    }
    public String getPart1() {
        return part1;
    }
    public void setPart1(String part1) {
        this.part1 = part1;
    }
    public String getPart2() {
        return part2;
    }
    public void setPart2(String part2) {
        this.part2 = part2;
    }
    public String getPart3() {
        return part3;
    }
    public void setPart3(String part3) {
        this.part3 = part3;
    }
    public String getPart4() {
        return part4;
    }
    public void setPart4(String part4) {
        this.part4 = part4;
    }
    public Info getInfo() {
        return info;
    }
    public void setInfo(Info info) {
        this.info = info;
    }
    @Override
    public String toString() {
        return this.hashCode() + " Product{" +
                "part1='" + part1 + '\'' +
                ", part2='" + part2 + '\'' +
                ", part3='" + part3 + '\'' +
                ", part4='" + part4 + '\'' +
                ", info=" + info +
                '}';
    }
    @Override
    protected Product clone() throws CloneNotSupportedException {
        //深拷贝
        Product clone = (Product) super.clone();
        Info info = this.info.clone();
        clone.setInfo(info);
        return clone;
    }
}

Info作为product的属性，同样实现Cloneable的clone方法，以便实现深拷贝

class Info implements Cloneable {
    private String name;
    public Info(String name) {
        this.name = name;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    @Override
    public String toString() {
        return this.hashCode() + " prototype.Info{" +
                "name='" + name + '\'' +
                '}';
    }
    @Override
    protected Info clone() throws CloneNotSupportedException {
        return (Info) super.clone();
    }
}

2.1.2 使用及测试

 public static void main(String[] args) throws CloneNotSupportedException {
        Info info1 = new Info("info1");
        Product product = new Product("part1", "part2", "part3", "part4", info1);
        //clone
        Product clone = product.clone();
        //打印对比
        System.out.println("original: "+product);
        System.out.println("clone: "+clone);
        //打印结果：可以看到hashcode 不一样，说明已经实现了深拷贝
        // original: 460141958 Product{part1='part1', part2='part2', part3='part3', part4='part4', info=1163157884 prototype.Info{name='info1'}}
        // clone: 1956725890 Product{part1='part1', part2='part2', part3='part3', part4='part4', info=356573597 prototype.Info{name='info1'}}
        //修改info打印对比
        product.getInfo().setName("info2");
        System.out.println("original: "+product);
        System.out.println("clone: "+clone);
        // 打印结果：修改原始product.info后，clone.info没有变化，说明实现了深拷贝
        // original: 460141958 Product{part1='part1', part2='part2', part3='part3', part4='part4', info=1163157884 prototype.Info{name='info2'}}
        // clone: 1956725890 Product{part1='part1', part2='part2', part3='part3', part4='part4', info=356573597 prototype.Info{name='info1'}}
    }

2.2 序列化机制实现（不推荐）

修改clone实现逻辑

    @Override
    protected Product clone() throws CloneNotSupportedException {
        //深拷贝
//        Product clone = (Product) super.clone();
//        Info info = this.info.clone();
//        clone.setInfo(info);
//        return clone;
        ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
        try (ObjectOutputStream oss = new ObjectOutputStream(byteArrayOutputStream)) {
            oss.writeObject(this);
        } catch (IOException e) {
            e.printStackTrace();
        }
        ByteArrayInputStream byteArrayInputStream = new ByteArrayInputStream(byteArrayOutputStream.toByteArray());
        try (ObjectInputStream ois = new ObjectInputStream(byteArrayInputStream)) {
            Product product = null;
            product = (Product) ois.readObject();
            return product;
        } catch (IOException e) {
            e.printStackTrace();
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
        return null;
    }

3. 应用场景

当代码不应该依赖于需要复制的对象的具体类时，请使用Prototype模式 。

4. 优点

1. 可以不耦合具体类的情况下克隆对象
2. 避免重复的初始化代码
3. 更方便的构建复杂对象
   

   5. Spring源码中的应用

   org.springframework.beans.factory.support.AbstractBeanDefinition
   java.util.Arrays