初探装饰器模式-白红宇

初探装饰器模式

阅读量：6951 次

发布时间：2019-06-27

本文共 3156 字，大约阅读时间需要 10 分钟。

装饰器模式：动态地将责任附加到对象上，允许用户向现有对象添加新功能而不改变其结构。若要扩展功能，装饰器提供了比继承更有弹性的替代方案。

场景：假如有这样一个抽象装备类

package pattern.decorator;public abstract class Equipment {    int power;//战斗力    String desc = "";//介绍    public String getDesc(){        return desc;    }    //获取战斗力    public abstract int getPower();}

然后实现一个武器类继承上面的装备类

package pattern.decorator;public class Weapon extends Equipment {    public Weapon(){        desc = "屠龙宝刀";        power = 1000000;    }    @Override    public int getPower() {        return power;    }}

一段时间后，装备增加了进阶，时装，强化等功能，这些功能都可以提升战斗力，现在希望计算提升后的战斗力。

先不管其他方法是怎么实现这个需求的，让我们来看看装饰器模式是怎么设计的，并且不会改变上面的Weapon类。

首先，设计一个装备的装饰器抽象类

package pattern.decorator;public abstract class Decorator extends Equipment {    //显示都装饰了什么    public abstract String getDesc();}

然后实现强化，进阶，时装的装饰类

强化（强化一次战力提升1000）：

package pattern.decorator;public class StrengthDecorator extends Decorator {    Equipment equipment;//需要被装饰的装备    int strength = 0;//强化了多少    public StrengthDecorator(Equipment equipment,int strength){        this.equipment = equipment;        this.strength = strength;    }    @Override    public String getDesc() {        return "强化了"+strength+"次"+","+equipment.getDesc();    }    @Override    public int getPower() {        return equipment.getPower() + 1000*strength;    }}

进阶（进阶一次战力提升2000）：

package pattern.decorator;public class AdvanceDecorator extends Decorator {    Equipment equipment;//需要被装饰的装备    int advance = 0;//进阶了多少    public AdvanceDecorator(Equipment equipment, int advance){        this.equipment = equipment;        this.advance = advance;    }    @Override    public String getDesc() {        return "进阶了"+advance+"次"+","+equipment.getDesc();    }    @Override    public int getPower() {        return equipment.getPower() + 2000*advance;    }}

时装（根据不同的时装提升战力）：

package pattern.decorator;public class FactionDecorator extends Decorator {    Equipment equipment;//需要被装饰的装备    String faction = "";//进阶了多少    int add = 0;    public FactionDecorator(Equipment equipment, int faction){        this.equipment = equipment;        if(faction==1){            this.faction = "春节时装";            add = 5000;        }else{            this.faction = "普通时装";            add = 2500;        }    }    @Override    public String getDesc() {        return faction+","+equipment.getDesc();    }    @Override    public int getPower() {        return equipment.getPower() + add;    }}

最后实现个测试类看看装饰器模式是怎么运作的

package pattern.decorator; public class ShowController {
       public static void main(String[] args) {
           Equipment weapon = new Weapon();         System.out.println(weapon.getDesc()+",战力:"+weapon.getPower());         weapon = new AdvanceDecorator(weapon,10);         System.out.println(weapon.getDesc()+",战力:"+weapon.getPower());         weapon = new FactionDecorator(weapon,1);         System.out.println(weapon.getDesc()+",战力:"+weapon.getPower());         weapon = new StrengthDecorator(weapon,15);         System.out.println(weapon.getDesc()+",战力:"+weapon.getPower());     } }

运行结果：

屠龙宝刀,战力:1000000

进阶了10次,屠龙宝刀,战力:1020000

春节时装,进阶了10次,屠龙宝刀,战力:1025000

强化了15次,春节时装,进阶了10次,屠龙宝刀,战力:1040000

转载于:https://www.cnblogs.com/yzdtofly/p/9449355.html

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