软件设计16|命令模式

（1）Java版本

效果：

工程目录：

代码：

AbstractCommand.java

package command_mode;

public abstract class AbstractCommand {
    public abstract int execute(int value);
    public abstract int undo();
    public abstract int redo();
}

Adder.java

package command_mode;

public class Adder {
    private int number=0;
    public int add(int value) {
        number+=value;
        return number;
    }
}

CalculatorForm.java

package command_mode;

public class CalculatorForm {
    public AbstractCommand command;
    public void setAbstractCommand(AbstractCommand command) {
        this.command=command;
    }
    public void computer(int value) {
        int i=command.execute(value);
        System.out.println("执行运算,运算结果为:"+i);
    }
    public void undo() {
        int i=command.undo();
        System.out.println("执行undo,运算结果为:"+i);
    }
    public void redo() {
        int i=command.redo();
        System.out.println("执行redo,运算结果为:"+i);
    }
}

Client.java

package command_mode;

public class Client {
    public static void main(String[] args) {
        CalculatorForm form=new CalculatorForm();
        AbstractCommand command=new ConcreteCommand();
        form.setAbstractCommand(command);
        form.computer(10);
        form.computer(20);
        form.undo();
        form.redo();
        form.computer(30);
        form.undo();
        form.redo();
    }
}

ConcreteCommand.java

package command_mode;

public class ConcreteCommand extends AbstractCommand {

    public Adder adder=new Adder();
    public int value;
    
    @Override
    public int execute(int value) {
        // TODO Auto-generated method stub
        this.value=value;
        return adder.add(value);
    }

    @Override
    public int undo() {
        // TODO Auto-generated method stub
        return adder.add(-value);
    }

    @Override
    public int redo() {
        // TODO Auto-generated method stub
        return adder.add(value);
    }
}

（2）C++版本

效果如下：

代码如下：

#include<iostream>
using namespace std;

class AbstractCommand{
public:
    virtual int execute(int value) = 0;
    virtual int undo() = 0;
    virtual int redo() = 0;
};

class Adder {
private:
    int number = 0;
public:
    int add(int value) {
        number = number + value;
        return number;
    }
};

class ConcreteCommand :public AbstractCommand{
private:
    Adder* adder = new Adder();
    int _value=0;
public:
    int execute(int value) {
        _value = value;
        return adder->add(_value);
    }
    int undo() {
        return adder->add(-_value);
    }
    int redo() {
        return adder->add(_value);
    }
};

class CalculatorForm{
private:
    AbstractCommand* _command;
public:
    void setAbstractCommand(AbstractCommand* command) {
        _command = command;
    }
    void computer(int value) {
        int i = _command->execute(value);
        cout << "执行运算,运算结果为:" << i << endl;
    }
    void undo() {
        int i = _command->undo();
        cout << "执行undo,运算结果为:" << i << endl;
    }
    void redo() {
        int i = _command->redo();
        cout << "执行redo,运算结果为:" << i << endl;
    }
};

int main() {
    CalculatorForm* form = new CalculatorForm();
    AbstractCommand* command = new ConcreteCommand();
    form->setAbstractCommand(command);
    form->computer(10);
    form->computer(20);
    form->undo();
    form->redo();
    form->computer(30);
    form->undo();
    form->redo();
}