命令模式

java



//Invoker.java
package shiyan16;

public class Invoker {
    private Command command;
    public void setCommand(Command command) {
        this.command =command;
    }
    /**
     * 执行运算
     * @param value
     */
    public void addNum(int value) {
        command.execute(value);
    }
    /**
     * 撤回
     */
    public void undo() {
        int i = command.undo();
        if(i==-1){
            System.out.println("已撤销到初态");
        }else{
            System.out.println("执行成功，运算结果是："+i);
        }
    }
    /**
     * 恢复
     */
    public void redo() {
         int i = command.redo();
        if(i==-1){
            System.out.println("已重复到终态");
        }
        else{
            System.out.println("执行成功，运算结果是："+i);
        }
    }
}
//Command.java
package shiyan16;

public abstract class Command {
      public abstract int execute(int value);
      public abstract int undo();
      public abstract int redo();
}
//Adder.java
package shiyan16;

public class Adder {
     private int num =0;
     public int addOperate(int value) {
         num+=value;
         return num;
     }
}
//AddCommand.java
package shiyan16;

import java.util.Stack;

public class AddCommand extends Command{
     private Adder adder = new Adder();
     private Stack<Integer> unStack = new Stack<Integer>();// 撤回栈，用来记录所做的每一步操作，用于撤回
     private Stack<Integer> reStack = new Stack<Integer>();// 恢复栈，用来存储返回栈弹出的数据，用于恢复

     /**
      * 撤回
      */

     public int undo() {
         int i=0;
         if (unStack.isEmpty()) {
             i=-1;
         }else{
             Integer pop = unStack.pop();
             reStack.push(pop);   //将撤回栈中的栈顶元素弹出，并且压入恢复栈中
             if(!unStack.isEmpty()){//判断弹出数据后是否为空，如果为空，说明已撤回到最原始状态
                 i=unStack.peek();
             }
         }
         return i;
     }

     /**
      * 恢复
      */
     public int redo() {
         int i=0;
         if (reStack.isEmpty()) {
             i=-1;
         }else{//撤回时只要可以可以撤回，则撤回栈一定有数据
             Integer pop = reStack.pop();
             unStack.push(pop);
             i=pop;
         }
         return i;
     }

     /**
      * 执行计算，并进行栈的更新
      */
     public int execute(int value) {
         int v = 0;
         v = adder.addOperate(value);
         System.out.println(v);
         unStack.push(v);
         return v;
     }
}
//Client.java
package shiyan16;
public class Client {
    public static void main(String[] args) {
        Invoker inv = new Invoker();
        AddCommand command = new AddCommand();
        inv.setCommand(command);
        //计算
        System.out.println("计算过程:");
        inv.addNum(1);
        inv.addNum(2);
        inv.addNum(3);
        //多次撤回
        System.out.println("undo操作:");
        inv.undo();
        inv.undo();
        inv.undo();
        inv.undo();
        //多次恢复
        System.out.println("redo操作:");
        inv.redo();
        inv.redo();
        inv.redo();
        inv.redo();
    }
}






c++



#include<iostream>
#include<vector>
#include<stack>
using namespace std;
//接受者
class Adder {
private:
    int num;
public:
    Adder(){
        this->num=0;
    }
    int add(int value) {
        num += value;
        return num;
    }
};
//抽象命令
class Command {
public:
    virtual int execute(int value) = 0;
    virtual int undo() = 0;
    virtual int redo() = 0;
};
//具体命令
class AddCommand : public Command {
private:
    Adder adder;
    stack <int>unStack;
    stack <int>reStack;
public:
    int undo() {
        int i = 0;
        if (unStack.empty()) {
            i = -1;
        }
        else {
            reStack.push(unStack.top());
            unStack.pop();
            if (!unStack.empty()) {
                i = unStack.top();
            }
        }
        return i;
    }
    int redo() {
        int i = 0;
        if (reStack.empty()) {
            i = -1;
        }
        else {//撤回时只要可以可以撤回，则撤回栈一定有数据
            unStack.push(reStack.top());
            i = reStack.top();
            reStack.pop();
        }
        return i;
    }
    int execute(int value) {
        int v = 0;
        v = adder.add(value);
        cout << v << endl;
        unStack.push(v);
        return v;
    }
};
//调用者
class Invoker{
private:
    AddCommand command;
public:
    void setCommand(AddCommand command2) {
        command = command2;
    };
    void compute(int value) {
        command.execute(value);
    };
    void undo() {
        int i = command.undo();
        if (i == -1) {
            cout << "已撤销到初态" << endl;
        }
        else {
            cout << "执行成功，运算结果是：" << i << endl;
        }
    }
    void redo() {
        int i = command.redo();
        if (i == -1) {
            cout << "已恢复至终态" << endl;
        }
        else {
            cout << "执行成功，运算结果是：" << i << endl;
        }
    }
};
//测试函数
int main() {
    Invoker inv;
    AddCommand command;
    inv.setCommand(command);
    //计算
    cout << "计算过程：" << endl;
    inv.compute(1);
    inv.compute(2);
    inv.compute(3);
    //多次撤回
    cout << "undo操作：" << endl;
    inv.undo();
    inv.undo();
    inv.undo();
    inv.undo();
    //多次恢复
    cout << "redo操作：" << endl;
    inv.redo();
    inv.redo();
    inv.redo();
    inv.redo();
}