设计模式之Proxy模式

为其他对象提供一种代理以控制对这个对象的访问。

实现

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// 抽象主题类
class Subject {
public:
    virtual void request() = 0;
};

// 具体主题类
class RealSubject : public Subject {
public:
    void request() override {
        // ...
    }
};

// 代理类
class Proxy : public Subject {
public:
    Proxy(Subject* subject) : subject_(subject) {}

    void request() override {
        if (checkAccess()) {
            subject_->request();
            logRequest();
        }
    }

    bool checkAccess() {
        // ...
    }

    void logRequest() {
        // ...
    }

private:
    Subject* subject_;
};

int main() {
    Subject* realSubject = new RealSubject();
    Subject* proxy = new Proxy(realSubject);

    proxy->request();

    return 0;
}