设计模式之装饰者模式

装饰者模式简述

• 装饰者模式可以形象的比喻一所大房子,外面只有一个门.打开门里面还有门.打开门获取一点金钱.你可以无限的进门..

• Component（被装饰对象的基类）
• ConcreteComponent（具体被装饰对象）
• Decorator（装饰者抽象类）
• ConcreteDecorator（具体装饰者）
  
  

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类图

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代码

1. 定义一个抽象类(非必须)

   package com.pan.component;
   
   /**
    * 抽象类
    * 
    * @author xinyi.pan
    *
    */
   public abstract class Animal {
   
       private String name;
   
       public Animal(String name) {
           this.name = name;
       }
   
       public String getName() {
           return name;
       }
   }

2. 定义一个被装饰的接口(定义公共的方法).

   package com.pan.component;
   
   public interface Fight {
       
       //公共方法(门)
       public String fightPower() ;
       
   }

3. 单独类cat

   package com.pan.component;
   
   public class Cat extends Animal implements Fight {
   
       public Cat(String name) {
           super(name);
       }
       //基类的门,里面不再有门..
       public String fightPower() {
           return super.getName() +" fighting" ;
       }
       
   }

4. 单独类cattle

   package com.pan.component;
   
   public class Cattle extends Animal implements Fight {
   
       public Cattle(String name) {
           super(name);
       }
   
       public String fightPower() {
           return super.getName() + " sleep";
       }
   }

5. 定义抽象装饰类

   package com.pan.decorator;
   
   import com.pan.component.Fight;
   
   public abstract class AnimalDecorator implements Fight {
   
       private Fight fight;
       // 构造函数添加被装饰着对象
       public AnimalDecorator(Fight fight) {
           this.fight = fight;
       }
       
       //拆包装饰者
       public String fightPower() {
           //调用装饰者公共方法
           doDecoratorFight();
           //打开下一个门
           return fight.fightPower();
       }
       
       //装饰者的公共方法.
       public abstract void doDecoratorFight() ;
   
   }

6. cattle装饰类

   package com.pan.decorator;
   
   import com.pan.component.Fight;
   
   public class CattleDecorator extends AnimalDecorator {
   
       public CattleDecorator(Fight fight) {
           super(fight);
       }
   
       @Override
       public String fightPower() {
           return super.fightPower();
       }
   
       @Override
       public void doDecoratorFight() {
           System.out.println("cattle 打豆豆");
       }
       
   }

7. 测试方法

   package com.pan.test;
   
   import com.pan.component.Cat;
   import com.pan.decorator.CatDecorator;
   import com.pan.decorator.CattleDecorator;
   
   public class CalTest {
   
       public static void main(String[] args) {
           
           System.out.println("==================未装饰cat==================");
           System.out.println(new Cat("cat").fightPower());
           System.out.println("===================装饰cat======================");
           CatDecorator catDecorator = new CatDecorator(new Cat("cat")) ;
           System.out.println(catDecorator.fightPower());
           CattleDecorator cattleDecorator = new CattleDecorator(catDecorator) ;
           System.out.println("====================cattle装饰cat装饰=====================");
           System.out.println(cattleDecorator.fightPower());
       }
   
   }

8. 结果

   ==================未装饰cat==================
   cat fighting
   ===================装饰cat======================
   cat 打豆豆
   cat fighting
   ====================cattle装饰cat装饰=====================
   cattle 打豆豆
   cat 打豆豆
   cat fighting

End