二十五.命令模式

命令模式：

Command:将一个请求封装为一个对象，从而使你可用不同的请求对客户进行参数化；对请求排队或记录请求日志，以及支持可撤销的操作。

常用情况&&优点：

1， 较容易的设计一个命令列队

2， 较容易的将命令记入日志

3， 允许接收请求的一方决定是否否决请求

4， 支持可撤销的操作和重做

5， 加入新的具体命令类不影响其他类

6， 请求一个操作的对象与知道怎么执行一个操作的对象分割开

Demo1:

       //抽象命令类

   public abstract class Command

    {

       protected Barbecuer receiver;//烧烤者

       public Command(Barbecuer receiver)

       {

           this.receiver = receiver;

       }

       abstract public void ExcuteCommand();//执行命令

}

 

//烧烤者，具体的实现类

   public  class Barbecuer

    {

       //烤羊肉，具体方法1

       public void BakeMutton()

       {

           Console.WriteLine("烤羊肉。");

       }

       //烤鸡翅，具体方法2

       public void BakeChickenWing()

       {

           Console.WriteLine("烤鸡翅。");

       }

}

 

//具体命令类

   //烤羊肉命令

   class BakeMuttonCommand:Command

    {

       public BakeMuttonCommand(Barbecuer receiver) : base(receiver) { }

       public override void ExcuteCommand()

       {

           receiver.BakeMutton();//调用虚方法里被传入的具体烧烤者执行具体方法

       }

    }

   //烤鸡翅命令

   class BakeChickenWingCommand : Command

    {

       public BakeChickenWingCommand(Barbecuer receiver)

           : base(receiver )

       { }

       public override void ExcuteCommand()

       {

           receiver.BakeChickenWing();

       }

}

 

//服务员

   public class Waiter

    {

       private IList<Command> order=new List<Command>();

       //设置订单

       public void SetOrder(Command command)

       {

           if (command.ToString() == "")

           {

                Console.WriteLine("鸡翅没了");

           }

           else

           {

                order.Add(command);

                Console.WriteLine("增加订单"+command.ToString()+"时间"+DateTime.Now.ToString() );

           }

       }

       //取消订单

       public void CancelOrder(Command command)

       {

           order.Remove(command);

           Console.WriteLine("取消订单" + command.ToString() + "时间" + DateTime.Now.ToString());

       }

       //通知执行

       public void Notify()

       {

           foreach (Command c in order)

           {

                c.ExcuteCommand();

           }

       }

}

 

//开店前准备

           Barbecuer boy = new Barbecuer();

           Command bakeMuttonCommand1 = new BakeMuttonCommand(boy);

           Command bakeMuttonCommand2 = new BakeMuttonCommand(boy);

           Command bakeChickenWingCommand1 = new BakeChickenWingCommand(boy);

           Waiter girl = new Waiter();

           //开门营业

           girl.SetOrder(bakeChickenWingCommand1 );

           girl.SetOrder(bakeMuttonCommand1);

           girl.SetOrder(bakeMuttonCommand2);

           girl.CancelOrder(bakeChickenWingCommand1 );

           //点菜完毕通知厨房

           girl.Notify();

 

           Console.ReadKey();