工厂方法模式

工厂方法模式（FACTORY METHOD）是一种常用的类创建型设计模式,此模式的核心精神是封装类中变化的部分，提取其中个性化善变的部分为独立类，通过依赖注入以达到解耦、复用和方便后期维护拓展的目的。它的核心结构有四个角色，分别是抽象工厂；具体工厂；抽象产品；具体产品

package com.strife.pattern.factory;

/**
 * 工厂方法模式
 *
 * @author mengzhenghao
 * @date 2022/5/28
 */
public class FactoryMethod {

    public static void main(String[] args) throws Exception {
        new BjPizzaFactory("cheese");
        new BjPizzaFactory("pepper");
        new LdPizzaFactory("cheese");
        new LdPizzaFactory("cheese");
    }
}

/** 订购披萨 （抽象工厂）*/
abstract class AbstractPizzaFactory {

    public AbstractPizzaFactory(String pizzaType) throws Exception {
        AbstractPizza pizza = makePizza(pizzaType);
        if (pizza != null) {
            pizza.prepare();
            pizza.box();
        } else {
            System.out.println("暂无该品种");
        }

    }

    /** 制作披萨 */
    public abstract AbstractPizza makePizza(String pizzaType) throws Exception;
}

/** 北京披萨工厂（具体工厂） */
class BjPizzaFactory extends AbstractPizzaFactory {

    public BjPizzaFactory(String pizzaType) throws Exception {
        super(pizzaType);
    }

    @Override
    public AbstractPizza makePizza(String pizzaType) throws Exception {
        for (BjPizzaTypeEnum pizzaTypeEnum : BjPizzaTypeEnum.values()) {
            if (pizzaType.equals(pizzaTypeEnum.getPizzaType())) {
                return (AbstractPizza) Class.forName(pizzaTypeEnum.getClazz()).newInstance();
            }
        }
        return null;
    }
}

/** 伦敦披萨工厂（具体工厂） */
class LdPizzaFactory extends AbstractPizzaFactory {

    public LdPizzaFactory(String pizzaType) throws Exception {
        super(pizzaType);
    }

    @Override
    public AbstractPizza makePizza(String pizzaType) throws Exception {
        for (LdPizzaTypeEnum pizzaTypeEnum : LdPizzaTypeEnum.values()) {
            if (pizzaType.equals(pizzaTypeEnum.getPizzaType())) {
                return (AbstractPizza) Class.forName(pizzaTypeEnum.getClazz()).newInstance();
            }
        }
        return null;
    }
}

/** 披萨（抽象产品） */
abstract class AbstractPizza {

    /** 准备原材料 */
    public abstract void prepare();

    /** 打包 */
    public abstract void box();
}

/** 北京奶酪披萨（具体产品） */
class BjCheesePizza extends AbstractPizza {

    @Override
    public void prepare() {
        System.out.println("北京奶酪披萨准备原材料");
    }

    @Override
    public void box() {
        System.out.println("北京奶酪披萨准备打包");
    }
}

/** 北京胡椒披萨（具体产品）*/
class BjPepperPizza extends AbstractPizza {

    @Override
    public void prepare() {
        System.out.println("北京胡椒披萨准备原材料");
    }

    @Override
    public void box() {
        System.out.println("北京胡椒披萨准备打包");
    }
}

/** 伦敦奶酪披萨（具体产品） */
class LdCheesePizza extends AbstractPizza {

    @Override
    public void prepare() {
        System.out.println("伦敦奶酪披萨准备原材料");
    }

    @Override
    public void box() {
        System.out.println("伦敦奶酪披萨准备打包");
    }
}

/** 伦敦胡椒披萨（具体产品）*/
class LdPepperPizza extends AbstractPizza {

    @Override
    public void prepare() {
        System.out.println("伦敦胡椒披萨准备原材料");
    }

    @Override
    public void box() {
        System.out.println("伦敦胡椒披萨准备打包");
    }
}


enum BjPizzaTypeEnum {
    /** 北京奶酪披萨*/
    CHEESE("cheese", "com.strife.pattern.factory.BjCheesePizza"),

    /** 北京胡椒披萨*/
    PEPPER("pepper", "com.strife.pattern.factory.BjPepperPizza");


    private final String pizzaType;
    private final String clazz;

    BjPizzaTypeEnum(String pizzaType, String clazz) {
        this.pizzaType = pizzaType;
        this.clazz = clazz;
    }

    public String getPizzaType() {
        return pizzaType;
    }

    public String getClazz() {
        return clazz;
    }
}

enum LdPizzaTypeEnum {

    /** 伦敦奶酪披萨*/
    CHEESE("cheese", "com.strife.pattern.factory.LdCheesePizza"),

    /** 伦敦胡椒披萨*/
    PEPPER("pepper", "com.strife.pattern.factory.LdPepperPizza");


    private final String pizzaType;
    private final String clazz;

    LdPizzaTypeEnum(String pizzaType, String clazz) {
        this.pizzaType = pizzaType;
        this.clazz = clazz;
    }

    public String getPizzaType() {
        return pizzaType;
    }

    public String getClazz() {
        return clazz;
    }
}