学习是件开心事

装饰者模式

发表于

对已有的业务逻辑进一步的封装，使其增加额外的功能，用户在使用的时候可以任意组装，达到自己想要的效果。如java中的io流。

设计的时候需要设计若干个同等级的子类，这些平行的子类都继承自同一个父类，并且有入参为父类的构造方法。

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public class Food {
    private String name;
    public Food() {
    }
    public Food(String name) {
        this.name = name;
    }
    public String make() {
        return name;
    }
}
public class Bread extends Food {
    private Food basic_food;
    public Bread(Food basic_food) {
        this.basic_food = basic_food;
    }
    public String make() {
        return basic_food.make() + "+面包";
    }
}
public class Cream extends Food {
    private Food basic_food;
    public Cream(Food basic_food) {
        this.basic_food = basic_food;
    }
    public String make() {
        return basic_food.make() + "+奶油";
    }
}
public class Vegetable extends Food {
    private Food basic_food;
    public Vegetable(Food basic_food) {
        this.basic_food = basic_food;
    }
    public String make() {
        return basic_food.make()+ "+蔬菜";
    }
}

测试类和运行结果为

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public static void main(String[] args) {
       Food food = new Bread(new Vegetable(new Cream(new Food("香肠"))));
       System.out.println(food.make());
   }

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香肠+奶油+蔬菜+面包