UML

• 聚合(Aggregation)关系：大雁和雁群，上图中空心菱形+箭头表示聚合关系
• 组合(Composition)关系：大雁和翅膀 ，实心菱形+箭头表示组合(Composition)关系

测试代码

#include <iostream>
#include <stdio.h>
#include <mutex>//锁头文件using namespace std;class Component{
public:virtual void Operation() = 0;virtual ~Component(){}
};
class ConcreteComponent:public Component
{
public:void Operation(){cout << "ConcreteComponent" << endl;}
};class Decorator:public Component{
protected:Component *component = nullptr;
public:void SetComponent(Component *_component){this->component = _component;}void Operation(){if(component != nullptr){component->Operation();}}
};
class ConcreteDecoratorA:public Decorator
{
private:string addedState;
public:void Operation(){Decorator::Operation();addedState = "new State";cout << "具体装饰对象A的操作" << endl;}
};class ConcreteDecoratorB:public Decorator
{
public:void Operation(){Decorator::Operation();AddedBehavior();cout << "具体装饰对象B的操作" << endl;}
private:void AddedBehavior(){cout << "AddedBehavior" << endl;}
};
int main(void)
{ConcreteComponent *c = new ConcreteComponent();ConcreteDecoratorA *d1 = new ConcreteDecoratorA();ConcreteDecoratorB *d2 = new ConcreteDecoratorB();d1->SetComponent(c);d2->SetComponent(d1);d2->Operation();cout << "--endl--" << endl;return 0;
}

输出

ConcreteComponent
具体装饰对象A的操作
AddedBehavior
具体装饰对象B的操作
--endl--

装饰模式是利用SetComponent来对对象进行包装的。这样每个装饰对象的实现就和如何使用这个对象分离开了，每个装饰对象只关心自己的功能，不需要关心如何被添加到对象链当中

装饰模式变身

如果只有一个ConcreteComponent类而没有抽象的Component类，那么Decorator类可以是ConcreteComponent的一个子类。同样道理，如果只有一个ConcreteDecorator类，那么就没有必要建立一个单独的Decorator类，而可以把Decorator和ConcreteDecorator的责任合并成一个类

根据这段文字的描述，UML结构图变身后的形态

C++改写后的UML图和代码

代码：

#include <iostream>
#include <stdio.h>
#include <mutex>//锁头文件using namespace std;//“Person”类（ConcreteComponent）
class Person{
public:Person(){}Person(string _name):name(_name){}virtual void Show(){cout << "装扮的：" << this->name << endl;}
private:string name;
};
//服饰类（Decorator）
class Finery:public Person
{
public:Person *component = nullptr;void Decorate(Person *_component){this->component = _component;}virtual void Show(){if(component != nullptr){component->Show();}}
};
class fengyi:public Finery
{
public:virtual void Show(){cout << "风衣" << endl;Finery::Show();}
};class yundongxie:public Finery
{
public:virtual void Show(){cout << "运动鞋" << endl;Finery::Show();}
};
class mojing:public Finery
{
public:void Show(){cout << "墨镜" << endl;Finery::Show();}
};
class kouzhao:public Finery
{
public:void Show(){cout << "口罩" << endl;Finery::Show();}
};
class xifu:public Finery
{
public:void Show(){cout << "西服" << endl;Finery::Show();}
};
int main(void)
{cout << "装扮1" << endl;Person *p1 = new Person("lkmao");fengyi *fy = new fengyi();yundongxie *ydx = new yundongxie();fy->Decorate(p1);ydx->Decorate(fy);ydx->Show();cout << endl << "装扮2" << endl;Person *p2 = new Person("laoliu");mojing *mj = new mojing();kouzhao *kz = new kouzhao();xifu *xf = new xifu();mj->Decorate(p2);kz->Decorate(mj);xf->Decorate(kz);xf->Show();cout << "--endl--" << endl;return 0;
} 

输出

装扮1
运动鞋
风衣
装扮的：lkmao装扮2
西服
口罩
墨镜
装扮的：laoliu
--endl--

参考：https://blog.csdn.net/yueni_zhao/article/details/128946954