结构型模式————装饰器模式（3.1）
Posted noneplus
tags:
篇首语：本文由小常识网(cha138.com)小编为大家整理，主要介绍了结构型模式————装饰器模式（3.1）相关的知识，希望对你有一定的参考价值。
什么是装饰器模式？
【先吃三颗栗子：】
1.PC=主机+显示器+键盘+鼠标+鼠标垫
主机是核心，而其他的组成部分都是装饰。
2.手抓饼=饼+鸡蛋+培根+黄瓜
饼是核心，鸡蛋，培根是可选的，可以理解为装饰。
3.咖啡=咖啡+牛奶+冰+方糖
咖啡是核心，牛奶等可选。
比喻虽然形象生动，但是与实际或多或少会产生偏差。
抽象的解释：装饰器模式的目的——核心部分和装饰部分可以自由组合。
装饰器模式的功能
对于软件开发来说，聚焦于软件的灵活性和可扩展性。
装饰器模式要求：
- 装饰可选
- 装饰可扩展
- 核心部分可扩展
手抓饼中的装饰器模式
实现饼加各种配料的价格计算。
思路：
1.定义抽象类手抓饼，其中包含获取种类的抽象方法和获取价格的抽象方法。
2.然后定义两个分别为大份手抓饼和中份手抓饼来继承这个抽象类，重写两个方法定义种类和价格。
3.定义具体的配料类继承手抓饼抽象类，先定义构造器传入已经创建的手抓饼种类，然后重写种类和价格方法。
在网上看的一些博客，是创建出一个抽象的配料类来继承抽象产品类，然后用具体的配料类来实现抽象配料类，实现装饰。
可是如果直接将抽象产品类的方法全部定义抽象方法，配料类直接继承重写，实现装饰，功能上也是可以实现的，如下所示，Bacon类直接继承HandPancake，然后重写getName和getCost方法，实现装饰。似乎也没有问题：
但是设计模式毕竟是一种经验总结，如果有已经看出端倪的小伙伴们在下方留言交流一下吧！
直接继承HandPancake：
abstract class HandPancake
public abstract String getName();
public abstract int getCost();
class HandPancake_Big extends HandPancake
@Override
public String getName()
return "大份手抓饼";
@Override
public int getCost()
return 10;
class HandPancake_Mid extends HandPancake
@Override
public String getName()
return "中份手抓饼";
@Override
public int getCost()
return 8;
class Bacon extends HandPancake
private HandPancake handPancake;
Bacon(HandPancake handPancake)
this.handPancake=handPancake;
@Override
public String getName()
return handPancake.getName()+"加培根";
@Override
public int getCost()
return handPancake.getCost()+1;
class Cucumber extends HandPancake
private HandPancake handPancake;
Cucumber(HandPancake handPancake)
this.handPancake=handPancake;
@Override
public String getName()
return handPancake.getName()+"加黄瓜";
@Override
public int getCost()
return handPancake.getCost()+2;
class Ham extends HandPancake
private HandPancake handPancake;
Ham(HandPancake handPancake)
this.handPancake=handPancake;
@Override
public String getName()
return handPancake.getName()+"加火腿";
@Override
public int getCost()
return handPancake.getCost()+1;
public class APPlication
public static void main(String[] args)
HandPancake handPancake_big = new HandPancake_Big();
System.out.println("啥也不加"+handPancake_big.getName()+":"+handPancake_big.getCost());
handPancake_big = new Ham(handPancake_big);
System.out.println(handPancake_big.getName()+":"+handPancake_big.getCost());
handPancake_big = new Cucumber(handPancake_big);
System.out.println(handPancake_big.getName()+":"+handPancake_big.getCost());
handPancake_big = new Bacon(handPancake_big);
System.out.println(handPancake_big.getName()+":"+handPancake_big.getCost());
System.out.println("==============================");
HandPancake handPancake_mid = new HandPancake_Mid();
System.out.println("啥也不加"+handPancake_mid.getName()+":"+handPancake_mid.getCost());
handPancake_mid = new Ham(handPancake_mid);
System.out.println(handPancake_mid.getName()+":"+handPancake_mid.getCost());
handPancake_mid = new Cucumber(handPancake_mid);
System.out.println(handPancake_mid.getName()+":"+handPancake_mid.getCost());
handPancake_mid = new Bacon(handPancake_mid);
System.out.println(handPancake_mid.getName()+":"+handPancake_mid.getCost());
官方做法：
abstract class HandPancake
String name; //1
public String getName()
return name;
public abstract int getCost();
class HandPancake_Big extends HandPancake
HandPancake_Big() //2.通过构造器赋值
name="大份手抓饼";
@Override
public int getCost()
return 10;
class HandPancake_Mid extends HandPancake
HandPancake_Mid() //2.通过构造器赋值
name="中份手抓饼";
@Override
public int getCost()
return 8;
abstract class Condiments extends HandPancake //3.定义抽象接口
public abstract String getName();
class Bacon extends Condiments //4.继承抽象接口
private HandPancake handPancake;
Bacon(HandPancake handPancake)
this.handPancake=handPancake;
@Override
public String getName()
return handPancake.getName()+"加培根";
@Override
public int getCost()
return handPancake.getCost()+1;
class Cucumber extends Condiments
private HandPancake handPancake;
Cucumber(HandPancake handPancake)
this.handPancake=handPancake;
@Override
public String getName()
return handPancake.getName()+"加黄瓜";
@Override
public int getCost()
return handPancake.getCost()+2;
class Ham extends Condiments
private HandPancake handPancake;
Ham(HandPancake handPancake)
this.handPancake=handPancake;
@Override
public String getName()
return handPancake.getName()+"加火腿";
@Override
public int getCost()
return handPancake.getCost()+1;
public class APPlication
public static void main(String[] args)
HandPancake handPancake_big = new HandPancake_Big();
System.out.println("啥也不加"+handPancake_big.getName()+":"+handPancake_big.getCost());
handPancake_big = new Ham(handPancake_big);
System.out.println(handPancake_big.getName()+":"+handPancake_big.getCost());
handPancake_big = new Cucumber(handPancake_big);
System.out.println(handPancake_big.getName()+":"+handPancake_big.getCost());
handPancake_big = new Bacon(handPancake_big);
System.out.println(handPancake_big.getName()+":"+handPancake_big.getCost());
System.out.println("==============================");
HandPancake handPancake_mid = new HandPancake_Mid();
System.out.println("啥也不加"+handPancake_mid.getName()+":"+handPancake_mid.getCost());
handPancake_mid = new Ham(handPancake_mid);
System.out.println(handPancake_mid.getName()+":"+handPancake_mid.getCost());
handPancake_mid = new Cucumber(handPancake_mid);
System.out.println(handPancake_mid.getName()+":"+handPancake_mid.getCost());
handPancake_mid = new Bacon(handPancake_mid);
System.out.println(handPancake_mid.getName()+":"+handPancake_mid.getCost());
手抓饼的扩展性
- 创建手抓饼的种类
- 创建配料种类
官方的扩展：创建一个小份手抓饼继承Hanpancake，然后创建配料继承Condiments。
贴一下直接继承HandPancake的情况：
class HandPancake_Smalll extends HandPancake
class Egg extends HandPancake
abstract class HandPancake
public abstract String getName();
public abstract int getCost();
class HandPancake_Big extends HandPancake
@Override
public String getName()
return "大份手抓饼";
@Override
public int getCost()
return 10;
class HandPancake_Mid extends HandPancake
@Override
public String getName()
return "中份手抓饼";
@Override
public int getCost()
return 8;
class Bacon extends HandPancake
private HandPancake handPancake;
Bacon(HandPancake handPancake)
this.handPancake=handPancake;
@Override
public String getName()
return handPancake.getName()+"加培根";
@Override
public int getCost()
return handPancake.getCost()+1;
class Cucumber extends HandPancake
private HandPancake handPancake;
Cucumber(HandPancake handPancake)
this.handPancake=handPancake;
@Override
public String getName()
return handPancake.getName()+"加黄瓜";
@Override
public int getCost()
return handPancake.getCost()+2;
class Ham extends HandPancake
private HandPancake handPancake;
Ham(HandPancake handPancake)
this.handPancake=handPancake;
@Override
public String getName()
return handPancake.getName()+"加火腿";
@Override
public int getCost()
return handPancake.getCost()+1;
//========================
class HandPancake_Smalll extends HandPancake
@Override
public String getName()
return "小份手抓饼";
@Override
public int getCost()
return 5;
class Egg extends HandPancake
private HandPancake handPancake;
Egg(HandPancake handPancake)
this.handPancake=handPancake;
@Override
public String getName()
return handPancake.getName()+"加鸡蛋";
@Override
public int getCost()
return handPancake.getCost()+1;
public class APPlication
public static void main(String[] args)
HandPancake handPancake_big = new HandPancake_Big();
System.out.println("啥也不加"+handPancake_big.getName()+":"+handPancake_big.getCost());
handPancake_big = new Ham(handPancake_big);
System.out.println(handPancake_big.getName()+":"+handPancake_big.getCost());
handPancake_big = new Cucumber(handPancake_big);
System.out.println(handPancake_big.getName()+":"+handPancake_big.getCost());
handPancake_big = new Bacon(handPancake_big);
System.out.println(handPancake_big.getName()+":"+handPancake_big.getCost());
System.out.println("==============================");
HandPancake handPancake_mid = new HandPancake_Mid();
System.out.println("啥也不加"+handPancake_mid.getName()+":"+handPancake_mid.getCost());
handPancake_mid = new Ham(handPancake_mid);
System.out.println(handPancake_mid.getName()+":"+handPancake_mid.getCost());
handPancake_mid = new Cucumber(handPancake_mid);
System.out.println(handPancake_mid.getName()+":"+handPancake_mid.getCost());
handPancake_mid = new Bacon(handPancake_mid);
System.out.println(handPancake_mid.getName()+":"+handPancake_mid.getCost());
System.out.println("扩展性测试:");
HandPancake handPancake_small = new HandPancake_Smalll();
System.out.println("啥也不加"+handPancake_small.getName()+":"+handPancake_small.getCost());
handPancake_small = new Egg(handPancake_small);
System.out.println(handPancake_small.getName()+":"+handPancake_small.getCost());
运行结果：
以上是关于结构型模式————装饰器模式（3.1）的主要内容，如果未能解决你的问题，请参考以下文章