# 命令模式

属于行为型模式。
将一个请求封装成一个对象，从而可以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。

优点：

能够比较容易地设计一个命令队列
在需要的情况下，可以较容易地将命令记入日志
允许接收请求的一方决定是否要否决请求
可以容易地实现对请求的撤销和重做
容易扩展

# 类图

# 代码

# 命令类

	namespace BehavioralPatterns_CommandPattern
	{
	/// <summary>
	/// 命令
	/// </summary>
	public abstract class Command
	{
	public abstract string CommandName { get; }

	/// <summary>
	/// 执行者
	/// </summary>
	protected Executor MainExecutor;

	public Command(Executor executor)
	{
	MainExecutor = executor;
	}

	/// <summary>
	/// 执行命令
	/// </summary>
	public virtual void Execute()
	{
	MainExecutor.Execute(this);
	}
	}
	}

	namespace BehavioralPatterns_CommandPattern
	{
	public class Command_0 : Command
	{
	public override string CommandName => "Command_0";

	public Command_0(Executor executor) : base(executor) { }
	}
	}

	namespace BehavioralPatterns_CommandPattern
	{
	public class Command_1 : Command
	{
	public override string CommandName => "Command_1";

	public Command_1(Executor executor) : base(executor) { }

	}
	}

# 执行命令的类

	namespace BehavioralPatterns_CommandPattern
	{
	public class Executor
	{
	/// <summary>
	/// 执行命令
	/// </summary>
	public void Execute(Command command)
	{
	Console.WriteLine("Action: " + command.CommandName);
	}
	}
	}

# 接收请求的类

	namespace BehavioralPatterns_CommandPattern
	{
	/// <summary>
	/// 接收者
	/// </summary>
	public class Receiver
	{
	/// <summary>
	/// 储存所有的命令
	/// </summary>
	private List<Command> CommandList;

	public Receiver()
	{
	CommandList = new List<Command>();
	}

	/// <summary>
	/// 添加命令
	/// </summary>
	/// <param name="command"> 命令 & lt;/param>
	public void AddCommand(Command command)
	{
	// 如果不满足条件，就拒绝请求
	if (CommandList.Count >= 2)
	{
	// 添加日志
	Console.WriteLine("Time: " + DateTime.Now + "\tRefuseAddCommand: " + command.CommandName);
	}
	else
	{
	// 记录命令
	CommandList.Add(command);

	// 添加日志
	Console.WriteLine("Time: " + DateTime.Now + "\tAddCommand: " + command.CommandName);
	}
	}

	/// <summary>
	/// 取消命令
	/// </summary>
	/// <param name="command"> 命令 & lt;/param>
	public void RemoveCommand(Command command)
	{
	// 取消命令
	CommandList.Remove(command);

	// 添加日志
	Console.WriteLine("Time: " + DateTime.Now + "\tCancleCommand: " + command.CommandName);
	}

	/// <summary>
	/// 执行命令
	/// </summary>
	public void ExcuteCommand()
	{
	foreach (var item in CommandList)
	{
	item.Execute();
	}
	}
	}
	}

# 测试

	namespace BehavioralPatterns_CommandPattern
	{
	public class Program
	{
	private static void Main()
	{
	Executor executor = new Executor();
	Receiver receiver = new Receiver();
	Command command_0 = new Command_0(executor);
	Command command_1 = new Command_1(executor);

	receiver.AddCommand(command_0);
	receiver.AddCommand(command_1);
	receiver.AddCommand(command_1);

	receiver.RemoveCommand(command_1);

	Console.WriteLine();
	receiver.ExcuteCommand();
	}
	}
	}

运行结果：
Time: 2023/7/29 20:21:27 AddCommand: Command_0
Time: 2023/7/29 20:21:27 AddCommand: Command_1
Time: 2023/7/29 20:21:27 RefuseAddCommand: Command_1
Time: 2023/7/29 20:21:27 CancleCommand: Command_1

Action: Command_0