设计模式 6.原型模式

原型模式主要用于1.对象种类繁多，无法整合到一个类中；2.难以根据类生成实例；3.想解耦框架与生成的实例。主要依赖于 clone方法和 Cloneable接口

1.构建复制功能的接口

Product.java 继承 Cloneable，这样才可以调用clone()
use()是执行函数，具体执行什么由子类决定
createClone()是复制实例的函数

package prototype.framework;

public interface Product extends Cloneable {
    public abstract void use(String s);
    public abstract Product createClone();
}

2.构建管理控制类

Manager.java
Manager类使用Product接口来复制实例

package prototype.framework;

import java.util.HashMap;

public class Manager {
    private HashMap showcase = new HashMap();//创建hashMap储存原型
    public void register(String name, Product proto) {
        showcase.put(name, proto);//加入原型
    }
    public Product create(String protoname) {
        Product p = (Product)showcase.get(protoname);
        return p.createClone();//根据圆形进行复制
    }
}

3.具体实现

案例1

package prototype;

import prototype.framework.Product;

public class MessageBox implements Product {
    private char decochar;
    public MessageBox(char decochar) {
        this.decochar = decochar;
    }
    @Override
    public void use(String s) {
        int length = s.getBytes().length;
        for (int i = 0;  i < length + 4; i++) {
            System.out.print(decochar);
        }
        System.out.println("");
        System.out.println(decochar + " " + s + " " + decochar);
        for (int i = 0; i < length + 4; i++) {
            System.out.print(decochar);
        }
        System.out.println("");
    }

    @Override
    public Product createClone() {
        Product product = null;
        try{
            product = (Product)clone();
        } catch (CloneNotSupportedException e) {
            e.printStackTrace();
        }
        return product;
    }
}

案例2

UnderlinePen.java

package prototype;

import prototype.framework.Product;

public class UnderlinePen implements Product {
    private char ulchar;
    public UnderlinePen(char ulchar) {
        this.ulchar = ulchar;
    }
    @Override
    public void use(String s) {
        int length = s.getBytes().length;
        System.out.println("\"" + s + "\"");
        System.out.print(" ");
        for (int i = 0; i < length; i++) {
            System.out.print(ulchar);
        }
        System.out.println("");
    }

    @Override
    public Product createClone() {
        Product product = null;
        try {
            product = (Product)clone();
        } catch (CloneNotSupportedException e) {
            e.printStackTrace();
        }
        return product;
    }
}

测试

package prototype;

import prototype.framework.Manager;
import prototype.framework.Product;

public class Main {
    public static void main(String[] args) {
        Manager manager = new Manager();
        UnderlinePen underlinePen = new UnderlinePen('~');
        MessageBox mbox = new MessageBox('*');
        MessageBox sbox = new MessageBox('/');
        manager.register("strong message", underlinePen);
        manager.register("warning box", mbox);
        manager.register("slash box", sbox);

        Product p1 = manager.create("strong message");
        p1.use("Hello, world");
        Product p2 = manager.create("warning box");
        p2.use("Hello, world");
        Product p3 = manager.create("slash box");
        p3.use("Hello, world");

    }
}