设计模式之命令模式

在一些C#开发设计中采用了这样一种设计方式即，在Form界面上的每一个控件拥有一个独立的事件处理代码，这样会造成事件的处理代码和UI的紧耦合，不利于代码的复用，所以应该将UI和事件处理代码分离。

       将事件处理抽象成一个接口Icommander，其接口公布一个方法---void execute()；有了这样一个接口，从Icommander继承的实现类就可以拥有自己独特的处理代码，而与UI无关。

    对于每一个控件应该有一种方法，该方法可以指定这个控件与哪一个命令

关联。那我们可以这样处理，抽象一个接口Icommanderholder,其接口公布2个方法，void setcommander(Icommander cmd)，Icommander getcommander();    让控件也要实现该接口的方法。这种开发的思想就是------命令模式。有命令来驱动！

private void commandclick(object sender,EventArgs e)

{

           //有了这样的设计方法，不需要在写很多类似的代码段了

Icommander cmd=((Icommanderholder)sender).getcommander();

           cmd.execute();

}

private void init()

{

           EventHandler evh=new EventHandler(commandclick);

           btnred.Click+=evh;

           btnred.setcommander(new redcommand(this));//设定处理命令

           btnblue.Click+=evh;

           btnblue.setcommander(new bluecommand(this));//设定处理命令

    }

/*---------------------------------------------------------------------------------------------*/

using System;

using System.Drawing;

using System.Collections;

using System.ComponentModel;

using System.Windows.Forms;

using System.Data;

 

namespace WFM

{

 

 

    /// <summary>

    /// frmMain 的摘要说明。

    /// </summary>

    public class frmMain : System.Windows.Forms.Form

    {

           private WFM.commanderbutton btnblue;

           private WFM.commanderbutton btnred;

           /// <summary>

           /// 必需的设计器变量。

           /// </summary>

           private System.ComponentModel.Container components = null;

 

           public frmMain()

           {

                  //

                  // Windows 窗体设计器支持所必需的

                  //

                  InitializeComponent();

                  init();

                  //

                  // TODO: 在 InitializeComponent 调用后添加任何构造函数代码

                  //

           }

 

           /// <summary>

           /// 清理所有正在使用的资源。

           /// </summary>

           protected override void Dispose( bool disposing )

           {

                  if( disposing )

                  {

                         if (components != null)

                         {

                                components.Dispose();

                         }

                  }

                  base.Dispose( disposing );

           }

 

           #region Windows 窗体设计器生成的代码

           /// <summary>

           /// 设计器支持所需的方法 - 不要使用代码编辑器修改

           /// 此方法的内容。

           /// </summary>

           private void InitializeComponent()

           {

                  this.btnblue = new WFM.commanderbutton();

                  this.btnred = new WFM.commanderbutton();

                  this.SuspendLayout();

                  //

                  // btnblue

                  //

                  this.btnblue.BackColor = System.Drawing.Color.Lime;

                  this.btnblue.Location = new System.Drawing.Point(72, 64);

                  this.btnblue.Name = "btnblue";

                  this.btnblue.Size = new System.Drawing.Size(80, 32);

                  this.btnblue.TabIndex = 0;

                  this.btnblue.Text = "bluebtn";

                  //

                  // btnred

                  //

                  this.btnred.BackColor = System.Drawing.Color.Red;

                  this.btnred.Location = new System.Drawing.Point(216, 64);

                  this.btnred.Name = "btnred";

                  this.btnred.Size = new System.Drawing.Size(72, 32);

                  this.btnred.TabIndex = 1;

                  this.btnred.Text = "redbtn";

                  //

                  // frmMain

                  //

                  this.AutoScaleBaseSize = new System.Drawing.Size(6, 14);

                  this.ClientSize = new System.Drawing.Size(384, 237);

                  this.Controls.Add(this.btnred);

                  this.Controls.Add(this.btnblue);

                  this.Name = "frmMain";

                  this.Text = "天气晴朗,星星都出来了!";

                  this.ResumeLayout(false);

 

           }

           private void commandclick(object sender,EventArgs e)

           {

                  Icommander cmd=((Icommanderholder)sender).getcommander();

                  cmd.execute();

           }

           private void init()

           {

                  EventHandler evh=new EventHandler(commandclick);

                  btnred.Click+=evh;

                  btnred.setcommander(new redcommand(this));

                  btnblue.Click+=evh;

                  btnblue.setcommander(new bluecommand(this));

           }

           #endregion

 

           /// <summary>

           /// 应用程序的主入口点。

           /// </summary>

           [STAThread]

           static void Main()

           {

                  Application.Run(new frmMain());

           }

 

 

 

    }

    public interface Icommander

    {

           void execute();

    }

 

    public class redcommand:Icommander

    {

           #region commander 成员

 

           public redcommand(Form win)

           {

                  m_frm=win;

           }

           public void execute()

           {

                  // TODO:  添加 redcommand.execute 实现

                  m_frm.BackColor=System.Drawing.Color.Red;

           }

           private Form m_frm;

           #endregion

 

    }

    public class bluecommand:Icommander

    {

           #region commander 成员

 

           public bluecommand(Form win)

           {

                  m_frm=win;

           }

           public void execute()

           {

                  // TODO:  添加 redcommand.execute 实现

                  m_frm.BackColor=System.Drawing.Color.Lime;

           }

           private Form m_frm;

           #endregion

 

    }

 

    public interface Icommanderholder

    {

           void setcommander(commander cmd);

           Icommander getcommander();  

    }

 

    public

class commanderbutton:System.Windows.Forms.Button,Icommanderholder

    {

           #region commanderholder 成员

           private Icommander m_cmd;

           public void setcommander(Icommander cmd)

           {

                  // TODO:  添加 buttoncommander.setcommander 实现

                  m_cmd=cmd;

           }

 

           public Icommander getcommander()

           {

                  // TODO:  添加 buttoncommander.getcommander 实现

                  return m_cmd;

           }

 

           #endregion

 

    }

 

}