建造者模式

OPice

发布于 2021-09-07 17:03:47

2330

发布于 2021-09-07 17:03:47

介绍

将多个简单对象一个个的构建成复杂对象的过程，提供了一种对象创建或者说是组合的最佳方式。主要解决的问题，有时候一个“复杂对象”的构造，可能由于需求不同，需要各部分子对象不同组合，但是不同的组合算法是稳定的。简单的例子，饭店有多种不一样的菜式，荤素热凉，但是不一样的菜品组合在一起就是不一样的套餐。应用实例：StringBuilder、Function的compose。

demo

1、套餐和食材接口

public interface Combo {
    /**
     * 套餐名称
     * @return
     */
    public String name();

    /**
     * 价格
     * @return
     */
    public BigDecimal price();

    /**
     * 主要材料
     * @return
     */
    public void element();
}

public interface Ingredient {
    /**
     * 食材
     * @return
     */
    public String ingredient();
}

2、食材的实现类

public class Chili implements Ingredient{
    @Override
    public String ingredient() {
        return "chili";
    }
}

public class Egg implements Ingredient {
    @Override
    public String ingredient() {
        return "egg";
    }
}

public class Tomato implements Ingredient {
    @Override
    public String ingredient() {
        return "tomato";
    }
}

public class Rice implements Ingredient {
    @Override
    public String ingredient() {
        return "rice";
    }
}

public class Noodles implements Ingredient {
    @Override
    public String ingredient() {
        return "noodles";
    }
}

3、根据不一样的食材作出菜品，套餐的实现

public class NoodlesCombo implements Combo {
    @Override
    public String name() {
        return "noodles served with soy sauce";
    }

    @Override
    public BigDecimal price() {
        return BigDecimal.valueOf(25.0);
    }

    @Override
    public void element() {
        for (Ingredient ingredient :ingredientList){
            System.out.println(ingredient.ingredient());
        }
    }

    private List<Ingredient> ingredientList = new ArrayList<Ingredient>();

    public void addIngredient(Ingredient ingredient){
        ingredientList.add(ingredient);
    }
}

public class RiceCombo implements Combo {
    @Override
    public String name() {
        return "rice served with meat and vegetables on top";
    }

    @Override
    public BigDecimal price() {
        return BigDecimal.valueOf(30.0);
    }

    @Override
    public void element() {
        for (Ingredient ingredient :ingredientList){
            System.out.println(ingredient.ingredient());
        }
    }

    private List<Ingredient> ingredientList = new ArrayList<Ingredient>();

    public void addIngredient(Ingredient ingredient){
        ingredientList.add(ingredient);
    }
}

4、定义一个厨师类

public class Chef {
    /**
     * 盖浇饭套餐
     * @return
     */
    public Combo prepareRice(){
        RiceCombo riceCombo = new RiceCombo();
        riceCombo.addIngredient(new Rice());
        riceCombo.addIngredient(new Chili());
        riceCombo.addIngredient(new Egg());
        return riceCombo;
    }

    /**
     * 拌面套餐
     * @return
     */
    public Combo PrepareNoodles(){
        NoodlesCombo noodlesCombo = new NoodlesCombo();
        noodlesCombo.addIngredient(new Noodles());
        noodlesCombo.addIngredient(new Tomato());
        noodlesCombo.addIngredient(new Egg());
        return noodlesCombo;
    }
}

5、Test

public class BuilderTest {
    public static void main(String[] args) {
        Chef chef = new Chef();
        Combo prepareRice = chef.prepareRice();
        System.out.println(prepareRice.name()+":"+prepareRice.price());
        prepareRice.element();

        Combo prepareNoodles = chef.PrepareNoodles();
        System.out.println(prepareNoodles.name()+":"+prepareNoodles.price());
        prepareNoodles.element();
    }
}