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7. 命令模式

news 2025/7/21 8:17:47

一、解决的问题

将行为请求者与行为实现者解耦，当用户发出命令后，无需关注谁来执行命令。
将命令的发出者和命令的执行者完全隔离开。

二、设计类图

在这里插入图片描述

Client：创建具体的命令对象，并且设置命令对象的接收者
Invoker：命令传递者，要求命令对象执行请求
Command：定义命令的接口
ConcreteCommand：命令接口实现对象
Receiver：命令接收并执行

三、代码实现

3.1 设计类图

以电视机遥控器作为背景进行，类图如下

3.2 代码实现


#include <iostream>class TV
{
private:int currentChannel = 0;public:void changeChannel(int channel){this->currentChannel = channel;}void turnOff(){std::cout << "TV is off." << std::endl;}void turnOn(){std::cout << "TV is on." << std::endl;}
};class Command
{
public:virtual void execute() = 0;
};class CommandOn : public Command
{
private:TV* myTV;
public:CommandOn(TV* tv){myTV = tv;}void execute(){myTV->turnOn();}
};class CommandOff : public Command
{
private:TV* myTV;
public:CommandOff(TV* tv){myTV = tv;}void execute(){myTV->turnOff();}
};class CommandChange : public Command
{
private:TV* myTV;int channel;
public:CommandChange(TV* tv, int channel){myTV = tv;this->channel = channel;}void execute(){std::cout << "Switch Channel to " << channel << std::endl;myTV->changeChannel(channel);}
};class Control
{
private:Command* changChannel;Command* offCommand;Command* onCommand;public:Control(Command* changChannel, Command* off, Command* on){this->changChannel = changChannel;this->offCommand = off;this->onCommand = on;}void changeChannel(){changChannel->execute();}void turnOff(){offCommand->execute();}void turnOn(){onCommand->execute();}
};int main()
{TV* mytv = new TV();Command* on = new CommandOn(mytv);Command* off = new CommandOff(mytv);Command* channel = new CommandChange(mytv, 3);Control* control = new Control(channel, off, on);control->turnOn();control->changeChannel();control->turnOff();return 0;
}