Command模式的C#简单实现

借鉴了IssueVision的方式，实现了Web下的Button按钮点击事件 ,使用了事件和代理的原理。

Command模式的基本原理的东西，在网上可以找到，这个可以说是一个简单的实现模型，具有扩展性。

public class Command
    {
        public delegate void EnableChangedEventHandler(object sender, Command.EnableChangedEventArgs e);
        public virtual event EnableChangedEventHandler EnableChanged;
        public delegate void Action();

        public Command()
        {
            
        }
        private Action m_action;
        private bool m_isEnabled = true;        
        
        public bool IsEnabled
        {
            get
            {
                return m_isEnabled;
            }

            set
            {
                if (m_isEnabled != value)
                {
                    m_isEnabled = value;
                    if (EnableChanged != null)
                    {
                        EnableChanged(this, new EnableChangedEventArgs(IsEnabled));
                    }
                }
            }
        }

        public Command(Action action)
        {
            m_action = action;
        }

        // Invokes the method assigned to this command.
        public void Execute()
        {
            m_action();
        }
        
        public class EnableChangedEventArgs : EventArgs
        {
            private bool m_isEnabled = false;

            public bool IsEnabled
            {
                get
                {
                    return m_isEnabled;
                }
            }

            public EnableChangedEventArgs(bool isEnabled)
            {
                m_isEnabled = isEnabled;
            }
        }
    }

Commander类，扩展性就在这里

public abstract class Commander
    {
        protected Command aCommand;
        protected abstract void HandleEnableChangedEvent(object sender, Command.EnableChangedEventArgs e);
        protected Commander( Command inCommand)
        {
            aCommand = inCommand;
            aCommand.EnableChanged += new CommandPattern.Command.EnableChangedEventHandler(HandleEnableChangedEvent);
        }
    }

    public class WebButtonCommander : Commander
    {
        private System.Web.UI.WebControls.Button aButton;

        protected WebButtonCommander(System.Web.UI.WebControls.Button inButton,Command inComand) : base(inComand)
        {
            aButton = inButton;
            aButton.Click +=new EventHandler(this.HandleUIEvent);
        }
        protected override void HandleEnableChangedEvent(object sender, Command.EnableChangedEventArgs e)
        {
            aButton.Enabled = e.IsEnabled;
        }

        private void HandleUIEvent(object sender,EventArgs e)
        {
            aCommand.Execute();
        }

        public static void Connect(System.Web.UI.WebControls.Button inButton, Command inCommand)
        {
            WebButtonCommander unused = new WebButtonCommander(inButton,inCommand);
        }
    }

然后，如何使用这些呢？建议一个Web项目，在页面上放2个按钮，清楚的知道是哪个按钮事件发生了。

protected System.Web.UI.WebControls.Button btnFirst;
        protected System.Web.UI.WebControls.Button btnSecond;

        Command Definition#region Command Definition
        private Command FirstCommand = null;
        private Command SecondCommand = null;
        #endregion

/**//// <summary>
        /// 初始化按钮事件
        /// </summary>
        private void InitializeButton()
        {
            this.FirstCommand = new Command(new Command.Action(this.FirstAction));
            WebButtonCommander.Connect(this.btnFirst,this.FirstCommand);

            this.SecondCommand = new Command(new Command.Action(this.SecondAction));
            WebButtonCommander.Connect(this.btnSecond,this.SecondCommand);
        }

override protected void OnInit(EventArgs e)
        {
            //
            // CODEGEN: 该调用是 ASP.NET Web 窗体设计器所必需的。
            //
            InitializeComponent();
            InitializeButton();    // look at this
            base.OnInit(e);
        }

Button click Action#region Button click Action
        private void FirstAction()
        {
            // do first Action;
            Response.Write("FirstAction");
        }
        private void SecondAction()
        {
            Response.Write("SecondAction");
        }