设计模式12-命令模式

命令模式：将请求封装，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，及撤销操作。

namespace DesignModel.命令模式
{
    abstract class Command
    {
        protected Execer exe;
        public Command(Execer execer)
        {
            this.exe = execer;
        }
        abstract public void ExecCommand();
    }

    class CommandOne : Command
    {
        public CommandOne(Execer execer) : base(execer) { }
        public override void ExecCommand()
        {
            exe.ExecCommandOne();
        }
    }
    class CommandTwo : Command
    {
        public CommandTwo(Execer execer) : base(execer) { }
        public override void ExecCommand() => exe.ExecCommandTwo();

    }

    class Execer
    {
        public void ExecCommandOne() => Console.WriteLine("");
        public void ExecCommandTwo() => Console.WriteLine("");
     }


    class Builder
    {
        IList<Command> list = new List<Command>();
        public Builder SetBuilder(Command command)
        {
            list.Add(command);
            return this;
        }
        public void Remove(Command command)
        {
            list.Remove(command);
        }
        public void Notify()
        {
             list.All(x => { x.ExecCommand(); return true; });
        }
    }
}
 static void 命令模式()
        {
            Execer execer = new Execer();
            Command c1 = new CommandOne(execer);
            Command c2 = new CommandTwo(execer);
            var builder = new DesignModel.命令模式.Builder();
            builder.SetBuilder(c1).SetBuilder(c2).Notify();
         }

优点：

   1可以设计命令队列；

   2允许命令接收方否决命令；

   3新增具体命令类不影响其它部分。