装饰者模式

朴灿烈づ我的快乐病毒、 2022-05-26 10:52 179阅读 0赞

## 引言 ##

还是以热干面，加鸡蛋的热干面，加牛肉的热干面举例子

## 代码如下 ##

1.先创建一个面条的接口

public interface Noodle {
    
        public String getNoodleName();
    
        public Double getNoodlePrice();
    }

写一些具体的类去实现面条，比如说热干面

public class HotDryNoodle implements Noodle{ 
    
        @Override
        public String getNoodleName() {
            return "热干面";
        }
    
        @Override
        public Double getNoodlePrice() {
            return 4.0;
        }
    
    }

然后此时写一个面条的装饰器，这个装饰器应该实现有参的构造方法，传入什么面条就行，在面条的基础上加东西。

public abstract class NoodleDecorator implements Noodle{ 
    
        public Noodle noodle;
    
        public NoodleDecorator(Noodle noodle) {
            this.noodle = noodle;
        }
    
    }

现在可以写加鸡蛋的热干面，加牛肉的热干面了

public class AddBeafNoodle extends NoodleDecorator { 
    
        public AddBeafNoodle(Noodle noodle) {
            super(noodle);
        }
    
        @Override
        public String getNoodleName() {
            return noodle.getNoodleName()+"加牛肉";
        }
    
        @Override
        public Double getNoodlePrice() {
            return noodle.getNoodlePrice()+5.0;
        }
    
    }

public class AddEggNoodle extends NoodleDecorator{ 
    
        public AddEggNoodle(Noodle noodle) {
            super(noodle);
        }
    
        @Override
        public String getNoodleName() {
            return noodle.getNoodleName()+"加鸡蛋";
        }
    
        @Override
        public Double getNoodlePrice() {
            return noodle.getNoodlePrice()+2.0;
        }
    
    }

测试

public class TestMain {
    
        public static void main(String[] args) {
            HotDryNoodle hotDryNoodle = new HotDryNoodle();
    
            AddEggNoodle eggNoodle = new AddEggNoodle(hotDryNoodle);
            System.out.println(eggNoodle.getNoodleName());
            System.out.println(eggNoodle.getNoodlePrice());
    
            AddBeafNoodle beafNoodle = new AddBeafNoodle(hotDryNoodle);
            System.out.println(beafNoodle.getNoodleName());
            System.out.println(beafNoodle.getNoodlePrice());
    
            AddBeafNoodle beafAndEggNoodle = new AddBeafNoodle(new AddEggNoodle(hotDryNoodle));
            System.out.println(beafAndEggNoodle.getNoodleName());
            System.out.println(beafAndEggNoodle.getNoodlePrice());
        }
    }