asp.net Forums 之控件研究

今天看了一下asp.net Forums，来说说它的皮肤控件。

首先说说它的皮肤控件基类：SkinnedForumWebControl，这个类位于AspNetForums.Controls命名空间下。

#region VSS 

/* 
* $Header: /HiForums/Controls/BaseClasses/SkinnedForumWebControl.cs 1     05-10-26 15:04 Jacky $ 
* 
* $History: SkinnedForumWebControl.cs $ 
 * 
 * *****************  Version 1  *****************
 * User: Jacky        Date: 05-10-26   Time: 15:04
 * Created in $/HiForums/Controls/BaseClasses
 * 
 * *****************  Version 1  *****************
 * User: Jacky        Date: 05-10-21   Time: 14:20
 * Created in $/HiForums/Controls/BaseClasses
 * 
 * *****************  Version 3  *****************
 * User: Jacky        Date: 05-09-20   Time: 19:15
 * Updated in $/ASP.NET Forums/Controls/BaseClasses
*/

#endregion 

using System;
using System.IO;
using System.Web.UI;
using AspNetForums.Components;
using AspNetForums.Enumerations;

namespace AspNetForums.Controls
{
    [
        ParseChildren(true)
        ]
    /// <summary>
        /// 皮肤控件基类
        /// </summary>
        public abstract class SkinnedForumWebControl : Control, INamingContainer
    {
        #region 成员字段

        private ForumContext forumContext = ForumContext.Current;
        private string skinFilename = null;
        private string skinName = null;
//        string returnURL = null;
        private ITemplate inlineSkin = null;
        private ForumMode mode = ForumMode.User;

        #endregion

        #region 构造函数

        // *********************************************************************
        //  SkinnedForumWebControl
        //
        /// <summary>
        /// Constructor
        /// </summary>
        // ***********************************************************************/
        public SkinnedForumWebControl()
        {
            // What skin should be used?
            //
            if (forumContext.User.IsAnonymous)
            {
                skinName = Globals.Skin;
            }
            else
            {
                skinName = forumContext.User.Theme;
            }

        }

        #endregion

        #region 子控件创建

        // *********************************************************************
        //  CreateChildControls
        //
        /// <summary>
        /// This event handler adds the children controls.
        /// </summary>
        // ***********************************************************************/
        protected override void CreateChildControls()
        {
            Control skin = null;

            if (inlineSkin != null)
            {
                inlineSkin.InstantiateIn(this);

                InitializeSkin(this);

            }
            else
            {
                // Load the skin
                skin = LoadSkin();

                // Initialize the skin
                InitializeSkin(skin);

                Controls.Add(skin);
            }
        }

        #endregion

        #region 调用皮肤

        // *********************************************************************
        //  LoadControlSkin
        //
        /// <summary>
        /// Loads the names control template from disk.
        /// </summary>
        // ***********************************************************************/
        protected Control LoadSkin()
        {
            Control skin;
            string skinPath = Globals.GetSkinPath() + "/Skins/" + SkinFilename.TrimStart('/');
            string defaultSkinPath = Globals.ApplicationPath + "/Themes/default/Skins/" + SkinFilename.TrimStart('/');

            // Do we have a skin?
            if (SkinFilename == null)
                throw new Exception("You must specify a skin.");

            // Attempt to load the control. If this fails, we're done
            try
            {
                skin = Page.LoadControl(skinPath);
            }
            catch (FileNotFoundException)
            {
                // Ok we couldn't find the skin, let's attempt to load the default skin instead
                try
                {
                    skin = Page.LoadControl(defaultSkinPath);
                }
                catch (FileNotFoundException)
                {
                    throw new Exception("错误:皮肤文件  " + skinPath + " 没有找到. 皮肤必须被指定,以用于控件的呈现.");
                }
            }

            return skin;
        }

        #endregion

        #region 皮肤初始化(抽像类)

        // *********************************************************************
        //  InitializeSkin
        //
        /// <summary>
        /// Initialize the control template and populate the control with values
        /// </summary>
        // ***********************************************************************/
        protected abstract void InitializeSkin(Control skin);

        #endregion

        #region 公有属性:皮肤文件名

        // *********************************************************************
        //  SkinName
        //
        /// <summary>
        /// Allows the default control template to be overridden
        /// </summary>
        // ***********************************************************************/
        public string SkinFilename
        {
            get { return skinFilename; }
            set { skinFilename = value; }
        }

        #endregion

        #region 皮肤名

        // *********************************************************************
        //  SkinName
        //
        /// <summary>
        /// Used to construct paths to images, etc. within controls.
        /// </summary>
        /// 
        // ********************************************************************/ 
        protected string SkinName
        {
            get { return skinName; }
            set { skinName = value; }
        }

        #endregion

        #region 公有属性:皮肤

        public ITemplate Skin
        {
            get { return inlineSkin; }
            set { inlineSkin = value; }
        }

        #endregion

        #region 公有属性:论坛模式

        public ForumMode Mode
        {
            get { return mode; }
            set { mode = value; }
        }

        #endregion
    }
}

它继承于Control, INamingContainer，Control是所有控件的基类，而INamingContainer按口标识在 System.Web.UI.Page 对象的控件层次结构内创建新 ID 命名空间的容器控件，也就是说实现了此接口，它能够帮你完成父子控件的命名工作，实现如下效果：“tr1_td1_control1”。

SkinnedForumWebControl基类的主要工作是重写了基类的CreateChildControls方法。

protected override void CreateChildControls()
  {
   Control skin = null;

   if (inlineSkin != null)
   {
    inlineSkin.InstantiateIn(this);

    InitializeSkin(this);

   }
   else
   {
    // Load the skin
    skin = LoadSkin();

    // Initialize the skin
    InitializeSkin(skin);

    Controls.Add(skin);
   }
  }

当内部皮肤控件不为空时，加载内部皮肤控件。
注：这个内部皮肤控件是一个ITemplate（模板接口）里面可以放任意服务器端控件。

不然，由LoadSkin（）方法加载经子类指定了用户控件名称的皮肤控件初始化后添加到Controls中。

InitializeSkin（）是一个abstract方法，由子类来实现数据绑定，注册事件等行为。

LoadSkin方法如下：

protected Control LoadSkin()
  {
   Control skin;
   string skinPath = Globals.GetSkinPath() + "/Skins/" + SkinFilename.TrimStart('/');
   string defaultSkinPath = Globals.ApplicationPath + "/Themes/default/Skins/" + SkinFilename.TrimStart('/');

   // Do we have a skin?
   if (SkinFilename == null)
    throw new Exception("You must specify a skin.");

   // Attempt to load the control. If this fails, we're done
   try
   {
    skin = Page.LoadControl(skinPath);
   }
   catch (FileNotFoundException)
   {
    // Ok we couldn't find the skin, let's attempt to load the default skin instead
    try
    {
     skin = Page.LoadControl(defaultSkinPath);
    }
    catch (FileNotFoundException)
    {
     throw new Exception("错误:皮肤文件  " + skinPath + " 没有找到. 皮肤必须被指定,以用于控件的呈现.");
    }
   }

   return skin;
  }

 基类完成后，我们要做的就是实现各种皮肤的用户控件和子类控件。然后在网页上通过ContentContainer控件来调用。

这就是Asp.Net Forums的换肤原理，欢迎各位达人指正。