两种语言实现设计模式（C++和Java）（五：代理模式）

参考：https://blog.csdn.net/lh844386434/article/details/18045671

代理模式指为其他对象提供一种代理以控制对这个对象的访问。这样实现了业务和核心功能分离。

Subject: 抽象角色。声明真实对象和代理对象的共同接口。
Proxy: 代理角色。代理对象与真实对象实现相同的接口，所以它能够在任何时刻都能够代理真实对象。代理角色内部包含有对真实对象的引用，所以她可以操作真实对象，同时也可以附加其他的操作，相当于对真实对象进行封装。
RealSubject: 真实角色。它代表着真实对象，是我们最终要引用的对象

举例：大众汽车工厂讲车辆代理给上汽集团SAIC生产

1.C++代码

#include <iostream>

using namespace std;

class ICarFactory{
public:
    ICarFactory(){}
    virtual void productCar()=0;
};

class VolkswagenFactory:public ICarFactory{
public:
    VolkswagenFactory(){}
    void productCar(){
        cout << "Product Volkswagen Car" << endl;
    }
};

class FactorySaicProxy: public ICarFactory{
public:
    FactorySaicProxy(ICarFactory* factory){
        myFactory = factory;
    }
    void productCar(){
        myFactory->productCar();
    }

private:
    ICarFactory* myFactory;
};


int main()
{
    VolkswagenFactory* factory = new VolkswagenFactory();
    FactorySaicProxy* factoryProxy = new FactorySaicProxy(factory);
    factoryProxy->productCar();
}

2.Java代码

public interface ICarFactory {
    void produceCar();
}

public class VolkswagenFactory implements ICarFactory {
    @Override
    public void produceCar() {
        System.out.println("Produce Volkswagen Car");
    }
}


public class SaicFactoryProxy implements ICarFactory {

    private ICarFactory carFactory;

    SaicFactoryProxy(ICarFactory carFactory){this.carFactory = carFactory;}

    @Override
    public void produceCar() {
        carFactory.produceCar();
    }
}

public class Main {

    public static void main(String[] args){
        SaicFactoryProxy saicFactoryProxy = new SaicFactoryProxy(new VolkswagenFactory());
        saicFactoryProxy.produceCar();
    }
}