原型模式

原型模式(Prototype)，用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。原型模式其实就是从一个对象再创建另外一个可定制的对象，而且不需要知道任何创建的细节。

原型模式结构图

原型模式中的角色：

• Prototype：抽象原型类，声明克隆方法的接口。
• ConcretePrototype：具体原型类，实现抽象原型类中声明的克隆方法。

原型模式的简单实现

(1) 具体原型类

Object 类充当抽象原型类，clone() 方法为原型方法。

public class Resume implements Cloneable {

    private String name;
    private String sex;
    private String age;
    private String timeArea;
    private String company;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }

    public String getAge() {
        return age;
    }

    public void setAge(String age) {
        this.age = age;
    }

    public String getTimeArea() {
        return timeArea;
    }

    public void setTimeArea(String timeArea) {
        this.timeArea = timeArea;
    }

    public String getCompany() {
        return company;
    }

    public void setCompany(String company) {
        this.company = company;
    }

    public Resume clone() {
        Object obj = null;
        try {
            obj = super.clone();
            return (Resume)obj;
        } catch(CloneNotSupportedException e) {
            System.out.println("不支持复制！");
            return null;
        }
    }
}

(2) 客户端调用

public class Client {

    public static void main(String[] args) {
        Resume resume = new Resume();
        resume.setName("yuzhiyi");
        resume.setSex("男");
        resume.setAge("23");
        resume.setTimeArea("09:00");
        resume.setCompany("BA");
        System.out.println(resume.getName());
        System.out.println(resume.getSex());
        System.out.println(resume.getAge());
        System.out.println(resume.getTimeArea());
        System.out.println(resume.getCompany());

        Resume newResume = resume.clone();
        System.out.println(newResume.getName());
        System.out.println(newResume.getSex());
        System.out.println(newResume.getAge());
        System.out.println(newResume.getTimeArea());
        System.out.println(newResume.getCompany());
    }
}

浅复制

浅复制：被复制对象的所有变量都含有原来的对象相同的值，而所有的对其他对象的应用都仍然指向原来的对象。

public class Attachment {

    private String path;

    public void setPath(String path) {
        this.path = path;
    }

    public String getPath() {
        return path;
    }

    public void download() {
        System.out.println("下载文件"  + path);
    }
}

public class Resume implements Cloneable {

    private String name;
    private String sex;
    private String age;
    private String timeArea;
    private String company;
    private Attachment attachment;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }

    public String getAge() {
        return age;
    }

    public void setAge(String age) {
        this.age = age;
    }

    public String getTimeArea() {
        return timeArea;
    }

    public void setTimeArea(String timeArea) {
        this.timeArea = timeArea;
    }

    public String getCompany() {
        return company;
    }

    public void setCompany(String company) {
        this.company = company;
    }

    public Attachment getAttachment() {
        return attachment;
    }

    public void setAttachment(Attachment attachment) {
        this.attachment = attachment;
    }

    public Resume clone() {
        Object obj = null;
        try {
            obj = super.clone();
            return (Resume)obj;
        } catch(CloneNotSupportedException e) {
            System.out.println("不支持复制！");
            return null;
        }
    }
}

public class Client {

    public static void main(String[] args) {
        Resume resume = new Resume();
        Attachment attachment = new Attachment();
        resume.setAttachment(attachment);

        Resume newResume = resume.clone();

        System.out.println(resume== newResume); // false
        System.out.println(resume.getAttachment() == newResume.getAttachment()); // true
    }
}

深克隆

深克隆：无论原型对象的成员变量是值类型还是引用类型，都将复制一份给克隆对象，深克隆将原型对象的所有引用对象也复制一份给克隆对象

public class Attachment implements Serializable {

    private static final long serialVersionUID = 6704368236366246076L;
    
    private String path;

    public void setPath(String path) {
        this.path = path;
    }

    public String getPath() {
        return path;
    }

    public void download() {
        System.out.println("下载文件");
    }
}

public class Resume implements Serializable {

    private String name;
    private String sex;
    private String age;
    private String timeArea;
    private String company;
    private Attachment attachment;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }

    public String getAge() {
        return age;
    }

    public void setAge(String age) {
        this.age = age;
    }

    public String getTimeArea() {
        return timeArea;
    }

    public void setTimeArea(String timeArea) {
        this.timeArea = timeArea;
    }

    public String getCompany() {
        return company;
    }

    public void setCompany(String company) {
        this.company = company;
    }

    public Attachment getAttachment() {
        return attachment;
    }

    public void setAttachment(Attachment attachment) {
        this.attachment = attachment;
    }

    public Resume deepClone() throws IOException, ClassNotFoundException {

        // 对象写入流
        ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
        ObjectOutputStream objectOutputStream = new ObjectOutputStream(byteArrayOutputStream);
        objectOutputStream.writeObject(this);

        // 对象从流中取出
        ByteArrayInputStream byteArrayInputStream = new ByteArrayInputStream(byteArrayOutputStream.toByteArray());
        ObjectInputStream objectInputStream = new ObjectInputStream(byteArrayInputStream);
        return (Resume) objectInputStream.readObject();

    }
}

public class Client {

    public static void main(String[] args) {
        Resume resume = new Resume();
        Attachment attachment = new Attachment();
        resume.setAttachment(attachment);

        Resume newResume = null;
        try {
            newResume = resume.deepClone();
        } catch (IOException e) {
            e.printStackTrace();
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }

        System.out.println(resume== newResume); // false
        System.out.println(resume.getAttachment() == newResume.getAttachment()); // false
    }
}