命令模式

1.操作对象 和 操作一个操作的对象分开；被解耦的两个对象通过命令对象沟通；添加一个命令不影响其他类；  可记录 日志，事务

2.代码

C++

//command c++
#include <iostream>
#include <vector>
#include <string>
using namespace std;

enum WEAPON_MAGIC_TYPE{ KNIFE,SWORD,WAND,FAIR,WIND,ICE_STORM };
typedef int MAGIC_DIMENSION;

class aSoldier{
public:    
    MAGIC_DIMENSION COST_VALUE = 20;
    
    aSoldier(string s):name(s){}
    void changeWeapon(WEAPON_MAGIC_TYPE type) { this->weapen = type; cout<<this->name<<" take weapon:"<<this->weapen<<endl;}
    WEAPON_MAGIC_TYPE getWeapen()             { return this->weapen; } 
    void releaseMagic(WEAPON_MAGIC_TYPE type) { this->magicValue -= COST_VALUE; cout<<this->name<<" release magic:"<<type<<" left magic:"<<this->magicValue<<endl; }
    int  getMagicValue()                      { return magicValue; }
    void recover()                            { this->magicValue += COST_VALUE; cout<<this->name<<" left magic: "<<this->magicValue<<endl; }

private:
    string name;
    WEAPON_MAGIC_TYPE weapen = WEAPON_MAGIC_TYPE::KNIFE;
    MAGIC_DIMENSION magicValue = 100;
};

class Command{
public:
    virtual void setCmd(WEAPON_MAGIC_TYPE) = 0;
    virtual void execute()                 = 0;
    virtual void undo()                    = 0;
};

class useMagicCmd : public Command{
public:
    useMagicCmd(aSoldier* p):m_pSoldier(p){}
    void setCmd(WEAPON_MAGIC_TYPE argc) {
        this->useMagic = argc; 
    }
    void execute(){
        m_pSoldier->releaseMagic(this->useMagic);
    }
    void undo(){
        m_pSoldier->recover();
    }
private:
    aSoldier* m_pSoldier;
    WEAPON_MAGIC_TYPE useMagic;
};

class changeWeapenCmd : public Command{
public:
    changeWeapenCmd(aSoldier* p):m_pSoldier(p){}
    void setCmd(WEAPON_MAGIC_TYPE argc) {
        lastWeapon = m_pSoldier->getWeapen();
        changeWeapon = argc; 
    }
    void execute(){
        m_pSoldier->changeWeapon(changeWeapon);
    }
    void undo(){
        m_pSoldier->changeWeapon(lastWeapon);
    }
private:
    aSoldier* m_pSoldier;
    WEAPON_MAGIC_TYPE lastWeapon;
    WEAPON_MAGIC_TYPE changeWeapon;
};

class Control{
public:
    void setObj(Command* obj){ objVec.push_back(obj); }
    void notify(){
        for(auto c : objVec)
            c->execute();
        
        lastObjVec = objVec; 
        objVec.clear();
    }
    void undo(){
        for(auto c : lastObjVec)
            c->undo();
        lastObjVec.clear();
    }
private:
    vector<Command*> objVec;
    vector<Command*> lastObjVec;
};

int main(){
    aSoldier* dragonSolder  = new aSoldier("S_S_WanTong");
    
    Command* magicCmd       = new useMagicCmd(dragonSolder);
    magicCmd->setCmd(WEAPON_MAGIC_TYPE::ICE_STORM);             
    
    Command* weapenCmd      = new changeWeapenCmd(dragonSolder);
    weapenCmd->setCmd(WEAPON_MAGIC_TYPE::SWORD);               
    
    Control* control         = new Control();
    control->setObj(weapenCmd);                                //换剑
    control->notify();                                         //执行
    
    weapenCmd->setCmd(WEAPON_MAGIC_TYPE::WAND);                
    control->setObj(weapenCmd);                                //换魔杖
    control->setObj(magicCmd);                                 //释放暴风雪
    control->notify();                                         //执行
    
    control->undo();                                           //撤销上一步操作
    
    return 0;
}

Java

//command java

interface Command{
    public void execute();
    public void undo();
}
//NoCommand
class NoCommand implements Command{
    public void execute(){
        System.out.println("do nothing");
    }
    public void undo(){}
}

//LightOnCommand
class LightOnCommand implements Command{
    Light light;
    public LightOnCommand(Light light){
        this.light = light;
    }
    public void execute(){
        light.on();
    }
    public void undo(){
        light.off();
    }
}
//StereoOnWithCDCommand
class StereoOnWithCDCommand implements Command{
    Stereo stereo;
    public StereoOnWithCDCommand(Stereo stereo){
        this.stereo = stereo;
    }
    public void execute(){
        stereo.on();
        stereo.setCD();
        stereo.setVolume(11);
    }
    public void undo(){ /* ... */ }
}

//
class RemoteControl{
    Command[] onCommands;
    Command[] offCommands;
    Command undoCommand;
    
    public RemoteControl(){
        onCommands  = new Command[7];
        offCommands = new Command[7];
        
        Command noCommand = new NoCommand();
        
        for(int i = 0; i < 7; i++){
            onCommands[i]  = noCommand;
            offCommands[i] = noCommand;
        }
        undoCommand = noCommand;
    }
    public void setCommand(int slot,Command onCommand,Command offCommand){
        if(null != onCommand)
            onCommands[slot]  = onCommand;
        if(null != offCommand)
            offCommands[slot] = offCommand;
    }
    public void onButtonPushed(int slot){
        onCommands[slot].execute();
        undoCommand = onCommands[slot];
    }
    public void offButtonPushed(int slot){
        offCommands[slot].execute();
        undoCommand = offCommands[slot];
    }
    public void undoButtonPushed(){
        undoCommand.undo();
    }
    public String toString(){
        StringBuffer stringBuffer = new StringBuffer();
        stringBuffer.append("\n --- Remote Control ---\n");
        for(int i = 0; i < onCommands.length; i++){
            //not need if(onCommands[i] != null)
                stringBuffer.append("[slot " + i + " ] " + onCommands[i].getClass().getName());
            //if(offCommands[i] != null)
                stringBuffer.append("  " + offCommands[i].getClass().getName() + "\n");
        }
        return stringBuffer.toString();
    }
}

//Light
class Light{
    private String name;
    public Light(String name) { this.name = name; }
    public void on()          { System.out.println(this.name + "light on");  }
    public void off()         { System.out.println(this.name + "light off"); }
}
//stereo
class Stereo{
    public void on()             { System.out.println("stereo on");            }
    public void setCD()          { System.out.println("stereo setCD");         }
    public void setVolume(int i) { System.out.println("stereo setVolume: " + i);   }
}

//main
public class RemoteLoader{
    public static void main(String[] args){
        
        Light  livingRoomLight = new Light("Living Room");
        Light  kitchenLight    = new Light("Kitchen");
        Stereo stereo          = new Stereo();
        
        LightOnCommand        livingRoomLightOn = new LightOnCommand(livingRoomLight);
        LightOnCommand        kitchenLightOn    = new LightOnCommand(kitchenLight);
        StereoOnWithCDCommand stereoOn          = new StereoOnWithCDCommand(stereo);
        
        RemoteControl remoteControl = new RemoteControl();
        remoteControl.setCommand(0,livingRoomLightOn,null);
        remoteControl.setCommand(1,kitchenLightOn,null);
        remoteControl.setCommand(2,stereoOn,null);
        
        System.out.println(remoteControl);
        
        remoteControl.onButtonPushed(0);
        remoteControl.onButtonPushed(1);
        remoteControl.undoButtonPushed();
        remoteControl.onButtonPushed(2);
    }
}