策略模式

[toc]

策略模式

定义：策略模式定义了算法族，让他们之间可以相互替换，此模式让算法的变化独立于使用算法的客户。

鸭子类设计

#include "vector"
#include "iostream"
#include "algorithm"
using namespace std;
// 定义飞行行为抽象类
class FlyBehavior{
public:
    virtual void fly(){};
};
// 飞行行为特化
class FlyWithWinds: public FlyBehavior{
public:
    void fly() override {
        cout<<" i am flying "<<endl;
    }
};
class FlyNoWay: public FlyBehavior{
    void fly() override {
        cout<<" i can't fly "<<endl;
    }
};
class FlyRocket: public FlyBehavior{
    void fly() override {
        cout<<" i can fly like a rocket "<<endl;
    }
};
// 叫声行为
class QuackBehavior{
public:
    virtual void quack(){}
};
class Quack: public QuackBehavior{
    void quack() override {
        cout<<" i can bark bark "<<endl;
    }
};
class MeteQuack: public QuackBehavior{
    void quack() override {
        cout<<"<< Silence  >>"<<endl;
    }
};
// 所有鸭子基类
class Duck{
public:
    FlyBehavior *flyBehavior{};
    QuackBehavior *quackBehavior{};
    virtual void display(){};
    void performFly() const{
        flyBehavior->fly();
    }
    void performQuack() const{
        quackBehavior->quack();
    }
    static void swim(){
        cout<<"all ducks can swim..."<<endl;
    }
    // 用于动态改变行为
    void setBehavior(FlyBehavior *fb){
        flyBehavior=fb;
    }
};
// 模型鸭子
class ModelDuck: public Duck{
public:
    ModelDuck(){
        flyBehavior=new FlyNoWay();
        quackBehavior=new Quack();
    }
    void display() override {
        cout<<"i am a model duck"<<endl;
    }
};
class MallarDuck: public Duck{
public:
    MallarDuck(){
        quackBehavior=new Quack();
        flyBehavior=new FlyWithWinds();
    }
    void display() override {
        cout<<" i am a MallarDuck.. "<<endl;
    }
};
int main() {
    cout<<"hello world CLion"<<endl;
    Duck *model=new ModelDuck();
    // 调用performFly 该行为被委托给flyBehavior对象，该对象实例为FlyNoWay
    model->performFly();
    model->setBehavior(new FlyRocket()); // 运行时改变行为
    model->performFly();
    return 0;
}