装饰模式（Decorator）-山下的石雕厂

装饰模式：是对一个类进行各种功能的丰富，使用Decorator模式扩充类的功能会比用子类生成的方式更加的灵活。

装饰者与被装饰者拥有共同的超类。

类图：



我家有座山，山下有座石雕厂，石雕厂有打磨石狮子的机器

抽象构建角色（被装饰者）：石雕厂Carved类

具体构建角色（被装饰者的初始状态）：雕刻石狮子LionCarved

装饰角色（持有构件的实例）：机器 Machine

装饰类：CarvedHead CarvedBody CarvedTail

Carved类

package decorator2;

public abstract class Carved {

public abstract String toCarved();

}

LionCarved类

package decorator2;

public class LionCarved extends Carved{

public String toCarved(){
return "开始雕刻石狮子";
}
}

Machine类

package decorator2;

public abstract class Machine extends Carved{

}

CarvedHead类

package decorator2;

public class CarvedHead extends Machine{

Carved carved;

public CarvedHead(Carved carved){
this.carved = carved;
}

public String toCarved(){
return "先要雕刻头部";
}

}

CarvedBody类

public class CarvedBody extends Machine{

Carved carved;

public CarvedBody(Carved carved) {
this.carved = carved;
}

public String toCarved(){
return "然后雕刻身体";
}
}

CarvedTail类

package decorator2;

public class CarvedTail extends Carved{

Carved carved;

public CarvedTail(Carved carved){
this.carved = carved;
}

public String toCarved(){
return "最后雕刻尾巴";
}
}

测试Test类

package decorator2;

public class Test {

public static void main(String args[]){
Carved carved = new LionCarved();
System.out.println(carved.toCarved());
CarvedHead carvedHead = new CarvedHead(carved);
System.out.println(carvedHead.toCarved());
CarvedBody carvedBody = new CarvedBody(carved);
System.out.println(carvedBody.toCarved());
CarvedTail carvedTail = new CarvedTail(carved);
System.out.println(carvedTail.toCarved());
}
}

运行结果如下：