原型模式 Prototype Pattern

Specify the kinds of objects to create using a prototypical instance,and create new objects by copying this prototype.

用原型实例指定创建对象的种类，并且通过复制这些原型创建新的对象。

Java内置克隆机制：

实现Cloneable接口

覆盖Object的clone()方法。

抽象原型角色（Prototype）：该角色是一个抽象角色，通常有一个Java接口或抽象类实现，给出所有的具体原型类所需的接口。

package com.DesignPattern.Creational.Prototype;

public interface Prototype extends Cloneable {

    //克隆方法
    Prototype clone();
}

具体原型角色（Concrete Prototype）：该角色是被复制的对象，必须实现抽象原型接口。

package com.DesignPattern.Creational.Prototype;

public class ConcretePrototype implements Prototype {

    @Override
    public Prototype clone() {
        try {
            return (Prototype) super.clone();
        } catch (CloneNotSupportedException e) {
            e.printStackTrace();
            return null;
        }
    }
}

客户角色（Client）：该角色提出创建对象的请求。

package com.DesignPattern.Creational.Prototype;

public class Client {

    public void operation(Prototype example) {
        // 得到example的副本
        Prototype p = example.clone();
    }
}

原型模式的实例

Mail.java

package com.DesignPattern.Creational.Prototype;

public class Mail implements Cloneable {

    private String receiver;
    private String subject;
    private String appellation;
    private String contxt;
    private String tail;

    public Mail(String subject, String contxt) {
        this.subject = subject;
        this.contxt = contxt;
    }

    // 克隆方法
    public Mail clone() {
        Mail mail = null;
        try {
            mail = (Mail) super.clone();
        } catch (CloneNotSupportedException e) {
            e.printStackTrace();
        }
        return mail;
    }

    public String getReceiver() {
        return receiver;
    }

    public void setReceiver(String receiver) {
        this.receiver = receiver;
    }

    public String getSubject() {
        return subject;
    }

    public void setSubject(String subject) {
        this.subject = subject;
    }

    public String getAppellation() {
        return appellation;
    }

    public void setAppellation(String appellation) {
        this.appellation = appellation;
    }

    public String getContxt() {
        return contxt;
    }

    public void setContxt(String contxt) {
        this.contxt = contxt;
    }

    public String getTail() {
        return tail;
    }

    public void setTail(String tail) {
        this.tail = tail;
    }

}

ClientDemo.java

package com.DesignPattern.Creational.Prototype;

import java.util.Random;

public class ClientDemo {

    // 发送账单的数量，这个值是从数据库中获得的
    private static int MAX_COUNT = 6;

    public static void main(String[] args) {
        int i = 0;
        // 定义一个邮件对象
        Mail mail = new Mail("Activity", "there are ...");
        mail.setAppellation("copyright");
        while (i < MAX_COUNT) {
            // 克隆邮件
            Mail cloneMail = mail.clone();
            cloneMail.setAppellation(getRandString(5) + "G(M)");
            cloneMail.setReceiver(getRandString(5) + "@" + getRandString(8)
                    + ".com");
            // 发送邮件
            sendMail(cloneMail);
            i++;
        }
    }

    // 发送邮件
    public static void sendMail(Mail mail) {
        System.out.println("标题：" + mail.getSubject() + "\t收件人:"
                + mail.getReceiver() + "\t.....send Success!");
    }

    // 获得指定长度的随机字符串
    public static String getRandString(int maxLength) {
        String source = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
        StringBuffer sb = new StringBuffer();
        Random rand = new Random();
        for (int i = 0; i < maxLength; i++) {
            sb.append(source.charAt(rand.nextInt(source.length())));
        }
        return sb.toString();
    }
}