设计模式笔记：适配器模式

是一种结构型设计模式，使得不兼容的接口一起工作

原始使用

#include <iostream>
using namespace std;

class Target {
public:
    virtual ~Target() = default;
    virtual void DoSomeThing()
    {
        std::cout << "[Target] do some thing" << endl;
    }

};

int main()
{
    Target* target = nullptr;
    target = new Target();

    target->DoSomeThing();

    return 0;
}

类适配器

「类适配器」
以多继承方式实现。

Target: 客户端期望接口类

Adaptee: 实际需要的功能类

Adapter: 将接口类与功能类衔接的适配器类

Client: 客户端代码

#include <iostream>
using namespace std;

class Target {
public:
    virtual ~Target() = default;
    virtual void DoSomeThing()
    {
        std::cout << "[Target] do some thing" << endl;
    }

};

class Adaptee {
public:
    void DoSomeThing()
    {
        std::cout << "[Adaptee] do some thing" << endl;
    }

};

class Adapter : public Target, Adaptee {
public:
    void DoSomeThing()
    {
        Adaptee::DoSomeThing();
    }
};

int main()
{
    Target* target = nullptr;
    target = new Adapter();

    target->DoSomeThing();

    return 0;
}

对象适配器

「对象适配器」
在适配器类中，包装适配者（Adaptee）接口。

Target: 客户端期望接口类

Adaptee: 实际需要的功能类

Adapter: 将接口类与功能类衔接的适配器类

Client: 客户端代码

#include <iostream>
using namespace std;

class Target {
public:
    virtual ~Target() = default;
    virtual void DoSomeThing()
    {
        std::cout << "[Target] do some thing" << endl;
    }

};

class Adaptee {
public:
    void DoSomeThing()
    {
        std::cout << "[Adaptee] do some thing" << endl;
    }

};

class Adapter : public Target {
public:
    Adapter(Adaptee* adaptee) : adaptee_(adaptee) {}
    void DoSomeThing()
    {
        if (adaptee_) {
            adaptee_->DoSomeThing();
        }
    }

private:
    Adaptee* adaptee_;
};

int main()
{
    Target* target = nullptr;
    Adaptee* adaptee = new Adaptee();
    target = new Adapter(adaptee);

    target->DoSomeThing();

    delete adaptee;
    return 0;
}